Emerging inorganic materials in thin-film photovoltaics

27 - 29 June 2022, Edinburgh, UK Directing Biosynthesis VI

4-6 July 2022, Bath, UK and Online Emerging inorganic materials in thin-film photovoltaics #FDPhotovoltaics

Book of Abstracts

Registered charity number: 207890

Apply for free affiliate membership

using code EVENTS100

Recognition. Significance. Collaboration.

SAMANTHA PERALTA AMRSC POSTGRADUATE STUDENT UNIVERSITY OF SHEFFIELD

“The ability to network with other people, throughout the world, who are working in the same field of study is super, super important. The fact that I am able to discuss and find answers to questions and solutions faster than if I was working alone is invaluable.”

What will membership help you achieve? Join us today. rsc.li/membershipcategories

Introduction

Emerging inorganic materials in thin-film photovoltaics Faraday Discussion is organised by the Faraday Division of the Royal Society of Chemistry This book contains abstracts of the 26 posters presented at Emerging inorganic materials in thin-film photovoltaics Faraday Discussion . All abstracts are produced directly from typescripts supplied by authors. Copyright reserved. Oral presentations and discussions All delegates at the meeting, not just speakers, have the opportunity to make comments, ask questions, or present complementary or contradictory measurements and calculations during the discussion. If it is relevant to the topic, you may give a 5 minute presentation of your own work during the discussion. These remarks are published alongside the papers in the final volume and are fully citable. If you would like to present slides during the discussion please let the session chair know and load them onto the computer in the break before the start of the session. Faraday Discussion Volume Copies of the Discussion Volume will be distributed approximately 6 months after the meeting. To expedite this, it is essential that summaries of contributions to the discussion are received no later than Wednesday 13 July for questions and comments and Wednesday 27 July for responses. Posters Posters have been numbered consecutively: P01-P26 The poster session will take place: The posters will be available to view throughout the discussion by clicking on the link in the virtual lobby. During the dedicated poster sessions, the authors will be available to use the networking functions in the virtual lobby. Use the inbox in the top light blue bar of the virtual lobby screen to send the poster presenter a message or request a video call with them by clicking on their name in the networking section at the bottom of the screen. If you are a poster presenter, please ensure that you are logged into the poster room assigned to your poster number in the lobby. Poster Prize The Faraday Discussions poster prize will be awarded to the best student poster as judged by the committee. Networking sessions There will be regular breaks throughout the meeting for socialising, networking and continuing discussions started during the scientific sessions. During the networking sessions you will be able to join existing networking rooms or initiate one-to-one chats. In Person: Monday 4 July at 16.30 BST Virtually: Tuesday 5 July at 12:00 BST Existing networking rooms will be visible from the virtual lobby. To create a one-to-one chat, simply click on the name of the person you would like to speak to and select if you would like to have a private or public conversation. For a public conversation, other delegates can join your chat room. With thanks to our exhibitor

And our sponsor:

“The Institute of Physics Thin Films and Surfaces Group is special interest, member-driven group, which stimulates and supports research. We disseminate information and organise meetings and conferences where academic and industrial scientists can discuss the most recent advances.”

Scientific Committee

Invited Speakers

David Fermin (Chair) University of Bristol, UK

David Mitzi (Introductory lecture) Duke University, USA

David Scanlon (Co-chair) University College London, UK Jake Bowers University of Loughborough, UK Susan Schorr Helmholtz Zentrum Berlin, Germany

Aron Walsh (Closing remarks lecture) Imperial College London, UK

Mirjana Dimitrievska École Polytechnique Fédérale de Lausanne (EPFL), Switzerland

Charlotte Platzer-Bjorkman Uppsala University, Sweden

Jonathan Scragg University of Uppsala, Sweden

Byungha Shin KAIST, South Korea

Thomas Weiss University of Luxembourg, Luxembourg

Susanne Siebentritt Université du Luxembourg, Luxembourg

Jiang Tang Huazhong University of Science and Technology, China

Thomas Unold Helmholtz Zentrum Berlin, Germany

Faraday Discussions Forum

www.rscweb.org/forums/fd/login.php

In order to record the discussion at the meeting, which forms part of the final published volume, your name and e-mail address will be stored in the Faraday Forum. This information is used for the collection of questions and responses communicated during each session. After each question or comment you will receive an e-mail which contains some keywords to remind you what you asked, and your password information for the forum. The e-mail is not a full record of your question. You need to complete your question in full on the forum. The deadline for completing questions and comments is Wednesday 13 July.

The question number in the e-mail keeps you a space on the forum. Use the forum to complete, review and expand on your question or comment. Figures and attachments can be uploaded to the forum. If you want to ask a question after the meeting, please e-mail faraday@rsc.org. Once we have received all questions and comments, responses will be invited by e-mail. These must also be completed on the forum. The deadline for completing responses is Wednesday 27 July. Please note that when using the Forum to submit a question or reply, your name and registered e-mail address will be visible to other delegates registered for this Faraday Discussions meeting. Key points: • The e-mail is not a full record of your comment/question. • All comments and responses must be completed in full on the forum Deadlines: Questions and comments Wednesday 13 July Responses Wednesday 27 July

Poster presentations

P01

Band gap engineering of atomic layer deposited ZnxSn 1-x O buffer for efficient Cu(In,Ga)Se 2 solar cells Raphael Agbenyeke University of Bristol, UK Dual band gap grading strategies for high efficiency kesterite based thin film solar cells Jacob Antonio Andrade Arvizu Institut de Recerca en Energia de Catalunya (IREC), Spain

P02

P03

Zn 2 SbN 3-y O y : a new metastable photoactive material Elisabetta Arca Newcastle University, UK Alternative partner layer for thin film solar cells Nicole Fleck Northumbria University, UK

P05

P06

Low-temperature, solution-based synthesis of chalcogenide perovskites Chuck Hages University of Florida, USA Solar absorbers using CZTS nanocrystals: new insights in their properties from Raman spectroscopy Yevhenii Havryliuk Chemnitz University of Technology, Germany

P07

P08

Sn-doping for p-type Sb 2 Se 3 absorber solar cells Theodore Hobson University of Liverpool, UK

P09

Optimizations of Cs/Zr-supported TiO 2 nanostructures in electron transport layer to enhance the performance of perovskite solar cells Dr. H. M. Asif Javed University of Agriculture, Faisalabad, Pakistan Following the reaction: computational spectroscopy of chalcogenide perovskite BaZrS 3 Prakriti Kayastha Northumbria University, UK

P10

P11

Bandgap tuning in Sn(Ti,Zr)Se 3 chalcogenide perovskite by cationic substitution Rokas Kondrotas Center for Physical Sciences and Technology, Lithuania

P12

Se diffusion in CdSeTe photovoltaics Jacob Frank Leaver University of Liverpool, UK

P13

Lone-pair driven ferroelectric and piezoelectric response of germanium halide perovskites CsGeX 3 (X = Cl, Br, and I) Jiwoo Lee Imperial College London, UK Effect of Sb 2 Se 3 grain orientation on device efficiency, and evidence of the self-healing mechanism through structural relaxation. Roy Lomas-Zapata Durham University, UK Application of novel low-cost and transparent hole conductors with long-term stability in ultrasonic spray deposited Sb 2 S 3 -based solar cells Sreekanth Mandati Tallinn University of Technology, Estonia Want to improve on structural disorder in Cu-based quaternary chalcogenides? Let’s look at the divalent cation! David Matzdorff Helmholtz-Zentrum Berlin für Materialien und Energie, Germany Improved stability and electrical properties in CsPbIBr 2 thin films through magnesium and acetate co-doping Ahmet Nazligul University College London, UK Unravelling the impact of disorder on the electronic properties of mixed- metal chalcohalides Adair Nicolson University College London, UK The role of different window layers in Sb 2 Se 3 -based thin film solar cell Stefano Pasini Università degli studi di Parma, Italy

P14

P15

P16

P17

P18

P19

P20

Grain size control of novel photoferroic absorber bournonite (CuPbSbS 3 ) Oliver Rigby Durham University, UK Dopability in earth abundant chalcogenide absorbers: insights from computation Christopher Savory University College London, UK Surface electronic characterisation of Cu 2 ZnSn(S,Se) 4 Films prepared from Sn(II) and Sn(IV) precursor sources Alice Sheppard University of Bristol, UK Lone pair driven anisotropy in antimony chalcogenide semiconductors Xinwei Wang Imperial College London, UK Electrodeposition of mesoporous CdTe through an inverse cubic lyotropic liquid crystal template Joshua White University of Southampton/Diamond Light Source/ISIS Neutron and Muon Source, UK Inhomogeneous defect distributions in mixed-polytype metal halide perovskites Young-Won Woo Yonsei University, South Korea Correlative raman and SEM-EDX investigation of sputtered chalcogenide perovskite BaZrS 3 Hasan Arif Yetkin University of Luxembourg, Luxembourg

P21

P22

P23

P24

P25

P26

Band gap engineering of atomic layer deposited Zn x Sn 1-x O buffer for efficient Cu(In,Ga)Se 2 solar cells Raphael Edem Agbenyeke 1,2 , Soomin Song 3 , Bo Keun Park 2 , Gun Hwan Kim 2 , Jae Ho Yun 3 , Taek-Mo Chung 2 , Chang Gyoun Kim 2 , Jeong Hwan Han 4 , David J. Fermin 1 1 University of Bristol, UK, 2 Division of Advanced Materials, Korea Research Institute of Chemical Technology(KRICT), Republic of Korea, 3 Photovoltaics Laboratory, Korea Institute of Energy Research (KIER), Republic of Korea, 4 Department of Materials Science and Engineering, Seoul National University of Science and Technology, Republic of Korea Ternary zinc tin oxide (ZTO) is an attractive buffer material with the promising potential of replacing the n -CdS buffer in chalcocite and kesterite solar cells. Besides its non-toxic elemental composition, it offers important electrical and optical/bandgap engineering opportunities that are yet to be fully explored. In this study, ZTO thin films were grown by atomic layer deposition and systematically characterized with the aim of establishing correlations between film compositions and properties. Using a series of characterization techniques, the effect of Zn/Sn ratio on film growth rate, crystal structure, majority carrier concentrations and optical band gap was uncovered. Most importantly, a parabolic correlation was observed between bandgap and Zn/Sn composition, which allowed for band offset tuning in CIGSe solar cells. Device Voc’s increased by more than twofold from 299 mV for a pure ZnO buffer to 627 mV for ZTO buffer with 16 atomic percent of Sn. Band alignment studies revealed an upward shift in conduction band minimum of ZTO with Sn incorporation, which favors the formation of a spike-type conduction band offset at the CIGSe/ZTO interface and reduces interfacial recombination. The 13.9% champion conversion efficiency of the ZTO incorporated cell relative to the 14.4 % of the CdS reference cell highlighted the promising potential of ZTO buffer layers. References 1. Lee Y. S, Heo J, Siah S.C, et al. Ultrathin amorphous zinc-tin-oxide bufferlayer for enhancing heterojunction interface quality in metal-oxidesolar cells.Energ. Environ. Sci. 2013;6(7):2112-2118. 2. Wei J, Yin Z, Chen S.C, Zheng Q. Low-temperature solution-processedzinc tin oxide film as a cathode interlayer for organic solar cells.ACSAppl.Mater.Interfaces. 2017;9(7):6186−6193. 3. Gorrn P, Ghaffari F, Riedl T, Kowalsky W. Zinc tin oxide based driverfor highly transparent active-matrix OLED displays.Solid- State Electron.2009;53(3):329-331.

P01

Dual band gap grading strategies for high efficiency kesterite based thin film solar cells Jacob Andrade-Arvizu 1* , V. Izquierdo-Roca 1 ,Z. Jehl Li-Kao 2 , C. Malerba 3 , D. Sylla 1 , R. Fonoll-Rubio 1 , M. Guc 1 , M. Placidi 1,2 , M. Courel 4 , O. Vigil-Galán 5 , Y. Sánchez 1 , E. Saucedo 2 , and A. Pérez-Rodríguez 1,6 1 Institut de Recerca en Energia de Catalunya (IREC), Spain, 2 Photovoltaic Group, Spain, 3 Agenzia nazionale per le nuove tecnologie, Italy, 4 Centro Universitario de los Valles (CUValles), México, 5 Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional (ESFM-IPN), Mexico, 6 Institute of Nanoscience and Nanotechnology (IN 2 UB), Spain Renewable energy supplies based on thin film solar cells and focused on sustainable materials such as kesterite (CZTS) could perform very successfully in a wide variety of energy application scenarios. This is due to its potential to be deposited on flexible substrates, its aesthetics and selective transparency for integrations in construction and automotive industrial sectors. As well as its use in new energy concepts such as agrovoltaics or energetic portability concepts like the Internet of Things (IoT). The current kesterite devices hinder the potential energy conversion efficiencies of a single absorber layer PN junction. Therefore, the next generation of kesterite and chalcopyrite solar cells power energy efficiency improvements may be enhanced after developing novel and more strategic methodologies for collecting photon energy. Thus, the graded bandgap profiling in kesterite is proposed as a sustainable strategy to improve the Solar spectrum utilization, through the generation of internal quasi-electric fields situated along the thin films, increasing the drift and diffusion length of the minority charge carriers and finally improving the power conversion efficiency of the photovoltaic device. Hence, this work develops advanced material synthesis techniques and surface characterization, which, when integrated with the structural complexity of double graded bandgap profiles in kesterite (CZTGSSe) thin films, allow Nature to reveal several disruptive and novel properties of matter, deliberately manipulable when working in conditions out-of- thermodynamic equilibrium. References 1. Illya Prigogine. Irreversibility and randomness. Astrophys. Space Sci. 65, 371–381 (1979) 2. I. Prigogine, I. Stengers.Order out of chaos: man’s new dialogue with nature. Boulder, CO, New Science Library (1984) 3. R Benzi,G Paladin,G ParisiandA Vulpiani. On the multifractal nature of fully developed turbulence and chaotic systems J. Phys. A: Math. Gen. 17 3521 (1984) 4. Mehran Kardar, Giorgio Parisi, and Yi-Cheng Zhang. Dynamic Scaling of Growing InterfacesPhys. Rev. Lett. 56 , 889 (1986) 5. Jacob Andrade-Arvizu, Víctor Izquierdo-Roca, Ignacio Becerril-Romero, Pedro Vidal-Fuentes, Robert Fonoll-Rubio, Yudania Sánchez, Marcel Placidi, Lorenzo Calvo-Barrio, Osvaldo Vigil-Galán, and Edgardo Saucedo.Is It Possible To Develop Complex S–Se Graded Band Gap Profiles in Kesterite-Based Solar Cells? ACS Applied Materials & Interfaces 11(36), 32945-32956 (2019)

P02

Zn 2 SbN 3-y O y : a new metastable photoactive material Elisabetta Arca 1,2 , Stephan Lany 2 ,Wenhao Sun 3 , Gerbrand Ceder 3 , Andry Zakutayev 2 1 Newcastle University, UK, 2 Materials Science Center, Colorado USA, 3 Lawrence Berkeley National Laboratory, California USA Wurtize (WZ)-derived ternary nitrides are an interesting class of materials for optoelectronic application. A subset of these, constitutes the Zn-based ternary nitrides in wurtzite derived structure. Peculiar to this family of materials is their ability to accommodate large cation off-stoichiometry, but also large anion off-stoichiometry to the extent that these materials might be more appropriately called oxynitrides. An example of this is the Zn 3 MoN 4 -ZnMoN 2 system, where cation off-stoichiometry enables a continuous tuning of the composition between the two end points, while retaining the WZ structure, through a process that we defined as redox-mediatedstabilisation[1]. Most of the cations in the periodic table have been reported to form nitrides as either a monometallic or bimetallic compound. An exception to this rule was represented by antimony: M-Sb-N ternary compounds where Sb is acting as an anion are known, whereas the discovery of a ternary nitride where Sb is acting as a cation is far more recent.In this contribution, I will present the theoretical search for new ternary nitrides which lead to the discovery of the first ternary antimony nitrideZn 2 SbN 3 where antimony is a cation [2]. A data-mined structure prediction (DMSP) algorithm was used to identify the compound and evaluated the stability of the candidate crystal structures by comparing their density functional theory (DFT) formation energies to the competing phases. Combinatorial RF magnetron sputtering was used as growth technique, to enable access to high nitrogen chemical potential and fast screening of deposition conditions. It was found that this metastable compound could be synthesised over a wide range of deposition conditions, showing tunable optical and electrical properties as a function of the Sb content in the cation sub-lattice and growth conditions. The low native n-type conductivity and moderate carrier concentration, coupled with an almost ideal direct band gap (1.7 eV theoretical, ~1.4 eV experimental), make it a promising candidate as a photoactive material. Based on measured values of the ionization potential and the electron affinity, the applicability of this material as a photoactive absorber will be discussed [3]. References 1. Arca E., et. al., Redox-Mediated Stabilization in Zinc Molybdenum Nitrides, J. Am. Chem. Soc., 140, 4293, (2018) 2. Sun W., Bartel C.J., Arca E., et al., A map of the inorganic ternary metal nitrides. Nat. Mater. 18, 732, (2019) 3. Arca E. et al., Zn 2 SbN 3 : growth and characterization of a metastable photoactive semiconductor, Materials Horizons, 6, 1669, (2019)

P03

Alternative partner layer for thin film solar cells Nicole Fleck 1 , Devendra Tiwari 1 , Jon Major 2 , Frank Jaeckel 2 1 Northumbria University, United Kingdom, 2 University of Liverpool, Liverpool, UK

Cadmium Sulfide (CdS) is the most commonly employed partner layer in thin film solar cell technology. Despite the non-ideal band gap of 2.4 eV resulting in parasitic absorption and containing toxic cadmium, this layer has yet to be replaced by a suitable alternative. In this study, molybdenum-doped indium oxide (Mo:In 2 O 3 or IMO) is studied as a promising alternative partner layer for Sb 2 Se 3 solar cells. An additional challenge of Cd diffusion has been identified for this system. IMO has a suitably large bandgap and the stability of oxides which, in principle, could prevent interfacial interdiffusion. IMO also shows high carrier mobility and tunability of conduction band offset with Mo doping concentration [1], and thus has been proposed as a sustainable replacement to popular transparent conducting oxide – SnO 2 :In (ITO). Here we study the effect on device metrics as a function of IMO deposition temperature as well as device post-deposition annealing under inert (N 2 ) and air atmosphere conditions. The properties of sputtered IMO are found to depend strongly on the history of the sputtering target, which affects the morphology and structure of IMO layer, and in turn, the interface chemistry significantly. The spectral response of external quantum measurements indicates a presence of considerable recombination losses at Sb 2 Se 3 /IMO interface. To better understand the origin of the interfacial defects, compositional depth profiles are probed using secondary ion mass spectrometry, which points to extensive elemental-intermixing at the junction. Sb 2 Se 3 solar cell performances are also known to be sensitive to the presence of lattice mismatch with respect to base layer and oxygen content, which could also affect the observed device characteristics and is needed to be investigated further. This is the first demonstration of the use of IMO as a much-needed alternative buffer layer for Sb 2 Se 3 devices. The as-reported optimisation of deposition parameters for IMO films also open-up possibilities of its implementation in other emerging photovoltaic devices. References 1. Mater Horiz (2020)7:236

P05

Low-temperature, solution-based synthesis of chalcogenide perovskites Chuck Hages, Ruiquan Yang, Alex Jess University of Florida, USA Chalcogenide perovskites are an emerging class of semiconductor with the potential to replace the ubiquitous organic-inorganic hybrid metal halide perovskites as a high-performance photovoltaic absorber. This is a result of their predicted enhanced stability, favorable charge transport and absorption properties, and non-toxic nature – while maintaining the defect tolerance and high optoelectronic tunability typical of perovskites. In fact, their stability ultimately results in a high crystallization energy barrier for their formation. As a result, current syntheses fail to realize the potential of chalcogenide perovskites by requiring high temperatures (c. 1000 °C) and/or long reaction times. Accordingly, there is a significant lack of relevant experimental syntheses of chalcogenide perovskites. Additionally, present synthesis routes limit their amenability to tunable materials chemistry for controlling their material properties and synthesis into thin films. Therefore, a critical need exists to develop a low-temperature, solution-based synthesis route to realize chalcogenide perovskites as a next-generation PV technology. In this work we discuss our results in the low-temperature, solution-based synthesis of sulfide chalcogenide perovskite nanoparticles. Our initial results have focused on the synthesis of BaSnS 3 , BaZrS 3 , and BaHfS 3 (and related stoichiometries) as a proof-of-concept for the generalized solution-based synthesis of chalcogenide perovskite nanoparticles. Our research has focused on developing single-source precursors for Ba-S, Zr-S, Hf-S, and Sn-Sn with high-stability (from oxidation), favorable solubility, and low-decomposition temperature (<200 °C); these precursors are based on metal-thiocarbamate complexes. Nanoparticle synthesis of chalcogenide perovskites (and related stoichiometries) have been demonstrated in temperature ranges from 150 – 275 °C. In addition to synthesis, we will discuss structural stability of various synthesis products, use of our low-temperature metal-thiocarbamate complexes for the direct formation of thin films via low-temperature & reactive annealing, and the potential of chalcogenide perovskite nanoparticles in the grain-growth of thin films via reactive annealing.

P06

Solar absorbers using CZTS nanocrystals: new insights in their properties from Raman spectroscopy Yevhenii Havryliuk 1 , V. Dzhagan 3 , O. Selyshchev 1,2 , D.R.T. Zahn 1,2 1 Chemnitz University of Technology, Germany, 2 Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Germany, 3 V.E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, Ukraine Quaternary semiconductor Cu 2 ZnSnS 4 (CZTS) is a promising material for photovoltaic applications. The conversion efficiency already reached about 13%, but further improvement is precluded by coexistence of multiple structural modifications, impurity phases, antisite and other point defects. Most of these impurities can be probed by Raman spectroscopy, some even more reliably than by such conventional structural tool as X-ray diffraction (XRD). Unlike strongly overlapping diffraction patterns of CZTS and secondary phases, their vibrational patterns are very different. Further advantage of Raman spectroscopy is the ability to selectively detect tiny inclusions of other phases by resonantly exciting them with a suitable laser excitation. Furthermore, fast photoinduced effects can be detected. Here we investigate the CZTS NCs obtained by a low-temperature "green" aqueous colloidal synthesis in the form of liquid "inks". Raman spectra of the as-synthesized solutions showed the NCs possess kesterite structure. In order to clarify the possibility of the formation of secondary phases, NC samples of potential compounds were prepared under the same conditions. Then size-selected CZTS NC samples produced by fractionationing the parental colloids allowed the effect of phonon confinement to be separated from other factors influencing the Raman spectra. We found that for CZTS NCs the phonon-confinement effect of the strongest Raman-active mode is opposite to that of most semiconductors due to an anomalous phonon dispersion of that mode in CZTS. Most device applications require thin films with well defined parameters. We investigated CZTS NC films formed by drop-casting, spin- and spray-coating, as simple, fast, and scalable fabrication methods. We found that the conditions of film formation critically influence its crystallinity and other properties. In particular, a long drying time and the presence of humidity lead to the formation of the secondary phase Cu 2-x S and a transition from the ordered to the disordered kesterite phase. Improving the film crystallinity by flash-lamp annealing was observed in a certain range light powers. Summarizing, Raman spectroscopy has proven to be a very efficient tool for rapid and non-destructive structural characterization of CZTS NC films and excellently complements the commonly used techniques based on diffraction. References 1. O. Selyshchev, Ye. Havryliuk, M.Y. Valakh, V. O. Yukhymchuk, O. Raievska, O. L. Stroyuk, V. Dzhagan and D.R.T. Zahn, ACS Appl. Nano Mater. , 2020, 3 , 5706–5717. 2. Ye. Havryliuk, O. Selyshchev, M. Valakh, A. Raevskaya, O. Stroyuk, C. Schmidt, V. Dzhagan and D.R.T. Zahn, Beilstein J. Nanotechnol. , 2019, 10 , 222–227. 3. Ye. Havryliuk, M.Y. Valakh, V. Dzhagan, O. Greshchuk, V. Yukhymchuk, A. Raevskaya, O. Stroyuk, O. Selyshchev, N. Gaponik and D.R.T. Zahn, RSC Adv. , 2018, 8 , 30736–30746.

P07

Sn-doping for p-type Sb 2 Se 3 absorber solar cells Theodore Hobson 1 , Huw Shiel 1 ,Christopher N. Savory 2 , Jack E. N. Swallow 1 , Bhaskar Das 3 , Leanne A. H. Jones 1 , Matthew J. Smiles 1 , Pardeep K. Thakur 4 ,Tien-Lin Lee 4 , Chris Leighton 3 ,David O. Scanlon 2 , Vinod R. Dhanak 1 ,Ken Durose 1 , Tim D. Veal 1 ,and Jonathan D. Major 1 1 University of Liverpool, UK, 2 University College London, UK, 3 University of Minnesota, United States, 4 Harwell Science and Innovation Campus, UK Antimony selenide (Sb 2 Se 3 ) is a promising absorber material for use in photovoltaics, having achieved 9.2% power conversion efficiency [1] and exhibiting self-healing benign grain boundaries [2]. However, few studies report intentional doping of the absorber. We previously reported that our Sb 2 Se 3 films are n-type from unintentionally incorporated chlorine; these produced isotype n-type heterojunction solar cells with power conversion efficiency of 7.3% [3]. Here we show that bulk crystals of Sb 2 Se 3 exhibit p-type conductivity when doped with tin. The conductivity type and transport properties were measured by hot probe, capacitance- voltage profiling and Hall effect measurements and further confirmed by photoemission measurements of the valence band maximum to Fermi level separation versus depth by combining ultraviolet, x-ray, and hard x-ray photoemission spectroscopy. Near-surface band bending could thereby be determined by solving the Poisson equation to model the photoemission results. The challenges of determining the carrier-type of a low carrier concentration absorber material are described, along with the benefits of using multiple characterization techniques. The viability of using tin for p-type doping of Sb 2 Se 3 for device applications is discussed in light of the experimental results and also density functional theory calculations of the formation energy of Sn dopants and native defects versus Fermi level in the limits of Sb- and Se-rich chemical potentials. References 1. Z. Li, X. Liang, G. Li, H. Liu, H. Zhang, J. Guo, J. Chen, K. Shen, X. San, W. Yu, R. E. I. Schropp, and Y. Mai, 9.2%-Efficient Core-Shell Structured Antimony Selenide Nanorod Array Solar Cells. Nat. Commun. 10 (2019) 125. 2. Rhys E. Williams,Quentin M. Ramasse,Keith P. McKenna,Laurie J. Phillips,Peter J. Yates,Oliver S. Hutter,Ken Durose, Jonathan D. Major,andBudhika G. Mendis, Evidence for Self-healing Benign Grain Boundaries and a Highly Defective Sb 2 Se 3 -CdS Interfacial Layer in Sb 2 Se 3 Thin-Film Photovoltaics, ACS Appl. Mater. Interfaces 12 (2020) 21730–21738. 3. Theodore D. C. Hobson,Laurie J. Phillips,Oliver S. Hutter,Huw Shiel,Jack E. N. Swallow,Christopher N. Savory,Pabitra K. Nayak,Silvia Mariotti,Bhaskar Das,Leon Bowen,Leanne A. H. Jones,Thomas J. Featherstone,Matthew J. Smiles,Mark A. Farnworth,Guillaume Zoppi,Pardeep K. Thakur,Tien-Lin Lee,Henry J. Snaith,Chris Leighton,David O. Scanlon,Vinod R. Dhanak,Ken Durose, Tim D. Veal,and Jonathan D. Major, Isotype Heterojunction Solar Cells Using n-type Sb 2 Se 3 Thin Films, Chem. Mater. 32 (2020)2621–2630.

P08

Optimizations of Cs/Zr-supported TiO 2 nanostructures in electron transport layer to enhance the performance of perovskite solar cells Dr. H. M. Asif Javed 1 , Akbar Ali Qureshi 2 1 University of Agriculture, Pakistan, 2 National University of Sciences & Technology, Pakistan The evolution of the Perovskite solar cells (PSC) has been remarkable with several milestones achieved in recent years. However, the efficient charge collection and rapid electron transportation are the key parameters desirable for the development of optimized electron transport layer (ETL) in PSC. In this research work, Cs/Zr- Supported TiO 2 nanostructures were introduced as an ETL in a n–i–p planar configuration. The Cs/Zr-Supported TiO 2 nanostructures were characterized for morphological, structural and optical studies by using SEM, EDX, XRD, Raman, PL and UV-Vis spectroscopy techniques. The photocatalytic activity was investigated by CV, EIS and Tafel measurements. The superior power conversion efficiency (PCE) of 12.35 % was observed with 0.2 M Zr-doped TiO 2 based ETL in PSC. The remarkable PCE in 0.2 M Zr-doped TiO 2 nanoparticles-based PSC is attributed to significant enhancement in charge carrier extraction and due to less recombination reactions at interfaces. The stability of PSC was evaluated by thermal gravimetric analyses (TGA), which showed only 2.5 % weight loss up to 800◦C. Furthermore, it was observed that the Cs-TiO 2 nanotubes-based PSCs presented an enhanced PCE of 13.24 %, which is higher than those of the PSCs based on pure TiO 2 nanotubes. So, an enhanced PCE could be achieved by higher electron injection rate.

P09

Following the reaction: computational spectroscopy of chalcogenide perovskite BaZrS 3 Prakriti Kayastha and Giulia Longo Northumbria University, UK

The perovskite ABX 3 class of materials show great promise as photovoltaic materials, with low production costs, high efficiencies and a wide range tunability through structural and compositional variation. The most successful of these perovskites are lead-based halide perovskites. However, there are several outstanding questions around their toxicity and stability of these materials. Chalcogenide-based perovskites, with a less toxic transition metal on the B-site, have been proposed to address both of these issues. In particular, BaZrS 3 has been recently fabricated in the lab but there are relatively few computational studies to support this experimental work. Here we present results from calculations using Density Functional Theory and lattice dynamics. In particular, we will analyse the electronic structure of BaZrS 3 and evaluate the dynamical properties (phonon bandstructure) of this system. We will also discuss how our predictions will be used to support synthesis of the material via ball-milling and hot-injection nanoparticle synthesis. With this work, we hope to highlight how electronic structure methods can support experimental work and accelerate materials design.

P10

Bandgap tuning in Sn(Ti,Zr)Se 3 chalcogenide perovskite by cationic substitution Rokas Kondrotas 1 , Vidas Pakštas 1 , Remigijus Juškėnas 1 ,Arūnas Krotkus 1 , Artūras Suchodolskis 1 , Marius Franckevičius 1 , Katri Muska 2 , Xiaofeng Li 2 , Marit Kauk-Kuusik 2 , Algirdas Mekys 3 1 State Research Institute, Lithuania, 2 Tallinn University of Technology, Estonia, 3 Institute of Photonics and Nanotechnology, Lithuania Multi-junction solar cell design is currently the most viable strategy to surpass 30% power conversion efficiency (PCE). Combining wide bandgap perovskite solar cell with c-Si forming a tandem device allowed to achieve over 29% PCE 1 . However, the infrared part of solar spectrum (<1.1 eV) is not absorbed by such tandem device, that could otherwise add 5% in absolute PCE. Taking into account three-junction device architecture with c-Si as the middle sub-cell, the optimal bandgap for bottom sub-cell is 0.7 eV 2 . There are few materials with close to 0.7 eV bandgap much lest studied for low-cost high-efficiency photovoltaic application. In this work, we examined bandgap tuning possibilities in chalcogenide perovskite with an aim to obtain 0.7 eV bandgap. Inorganic chalcogenide perovskites with a general formula ABX 3 (X=S, Se) where A=Ca, Sr, Ba, B=Ti, Zr, Hf and X=Se, have been predicted to have bandgaps in 0.0 – 2.3 eV range 3 . However, low bandgap chalcogenide perovskites are rarely studied, and little is known about their optical properties from experimental perspective. In this work, we focus on synthesizing critical raw materials free and earth-abundant composition chalcogenide perovskite - Sn(Ti,Zr)Se 3 . Solid solutions of Sn(Ti,Zr)Se 3 were synthesized by solid state reaction. Crystalline phase composition and purity was confirmed using X-ray diffraction method and energy dispersive spectroscopy. Bandgap was estimated from diffuse reflectance measurements of powder. We found that within 0 to 0.25 Ti/(Ti+Zr) ratio range, Sn(Ti,Zr)Se 3 crystallized in a needle-like crystal structure (space group Pnma ) – the same as pure SnZrSe 3 . Estimated bandgap varied from 0.6 to 1.1 eV depending on the content of Ti. This showed that bandgap in Sn(Ti,Zr)Se 3 solid solution can be effectively tuned by cationic substitution and fined tuned to achieve 0.7 eV. References 1. Al-Ashouri A, Köhnen E, Li B, Magomedov A, Hempel H, Caprioglio P, et al. Monolithic perovskite/silicon tandem solar cell with> 29% efficiency by enhanced hole extraction. Science. 2020;370(6522):1300-9. 2. Guter W, Schöne J, Philipps SP, Steiner M, Siefer G, Wekkeli A, et al. Current-matched triple-junction solar cell reaching 41.1% conversion efficiency under concentrated sunlight. Applied Physics Letters. 2009;94(22):223504. 3. Sun Y-Y, Agiorgousis ML, Zhang P, Zhang S. Chalcogenide perovskites for photovoltaics. Nano letters. 2015;15(1):581-5.

P11

Se diffusion in CdSeTe photovoltaics Jacob Frank Leaver and Jonathan D. Major University of Liverpool, UK

CdSe x Te 1-x (CST) has emerged as an important component of the absorber in CdTe photovoltaics, where the Se content is graded so that x is highest at the front (light-facing) side of the absorber and decreases towards pure CdTe at the back. Due to band-bowing effects the bandgap of the CST in these devices is lower than CdTe, extending the absorption onset further into the infrared and increasing the short-ciruit current 1,2. There is also evidence that Se passivates defects in this material, reducing nonradiative recombination and increasing the open-circuit voltage 3,4 . This work investigates the effect of device fabrication and processing conditions on Se diffusion in CST devices, and the resulting impact on device performance. References 1. N. Paudel and Y. Yan, Appl. Phys. Lett. , 2014, 105 , 183510 2. X. Zheng, D. Kuciauskas, J. Moseley, E. Colegrove, D. S. Albin, H. Moutinho, J. N. Duenow, T. Ablekim, S. P. Harvey, A. Ferguson and W. K. Metzger, APL Mater. , 2019, 7 , 071112 3. D. Kuciauskas, J. Moseley, P. Ščajev and D. Albin, Physica Status Solidi-R , 2020, 14 , 1-6 4. T. A. M. Fiducia, A. Howkins, A. Abbas, B. G. Mendis, A. Munshi, K. Barth, W. Sampath and J. M. Walls, Sol. Energ. Mat. Sol. C. , 2022, 238 , 111595

P12

Lone-pair driven ferroelectric and piezoelectric response of germanium halide perovskites CsGeX 3 (X = Cl, Br, and I) Jiwoo Lee, Young-Kwang Jung, Zhenzhu Li, Aron Walsh Imperial College London, United Kingdom Computational screening via density-functional-theory calculations reports Ge as a candidate element for substituting Pb in halide perovskite compounds suitable for light harvesting; and clarifying the existence of ferroelectricity and piezoelectricity in halide perovskites have important technological consequences as ferroelectric nanodomains can reduce the recombination of light-excited electron-hole pairs and extend the carrier lifetime [1,2]. The explanation for the origin of spontaneous polarization in germanium halide perovskites in terms of an on-site second-order Jahn-Teller effect has not been hitherto investigated [3]. In this work, we report the interaction between Ge and the anion mainly derives the magnitude of the spontaneous polarization. The role of the anion p atomic orbital in chemical bonding is key to explain why CsGeCl 3 has the largest spontaneous polarization value of 19 μ C/cm 2 [4]. We expect that the computational exploration of lone pair systems offers a key insight to design novel photoelectric devices. References 1. Lead-free germanium iodide perovskite materials for photovoltaic applications. J. Mater. Chem. A , 3, 23829-23832(2015) ; https://doi.org/10.1039/C5TA05741H 2. F erroelectric Alignment of Organic Cations Inhibits Nonradiative Electron–Hole Recombination in Hybrid Perovskites: Ab Initio Nonadiabatic Molecular Dynamics. J. Phys. Chem. Lett. 8, 4, 812–818 (2017) ; https://doi.org/10.1021/acs. jpclett.7b00008 3. Resolving the Physical Origin of Octahedral Tilting in Halide Perovskites. Chem. Mater. 28, 12, 4259–4266 (2016) ; https:// doi.org/10.1021/acs.chemmater.6b00968 4. Stereochemistry of post-transition metal oxides: revision of the classical lone pair model. Chem. Soc. Rev. 40 , 4455-4463 (2011) ; https://doi.org/10.1039/C1CS15098G

P13

Effect of Sb 2 Se 3 grain orientation on device efficiency, and evidence of the self-healing mechanism through structural relaxation Roy Lomas-Zapata 1 , LJ Philips 2 , JD Major 2 , BG Mendis 1 1 Durham University, UK, 2 University of Liverpool, UK Due to the highly anisotropic nature of the Sb 2 Se 3 structure, carrier transport along the [001] ribbon direction is the most efficient since it occurs along covalent bonded atoms. For transport to occur along any other direction it would be necessary for electrons to “hop” between adjacent ribbons, which is inefficient. In practice however, growth along (211), and (221) plane normals is predominant in Sb 2 Se 3 thin-films. Given that these directions are not parallel to [001], grain boundaries for these growth textures produce dangling bonds that can act as recombination centres, and therefore have a direct impact on device efficiency. However, recent density-functional theory (DFT) work has shown that significant structural relaxation can also take place, thereby removing the harmful defect electronic states at Sb 2 Se 3 grain boundaries. 1 In this study, an orientation-dependant solar cell simulation methodology was developed to analyse the effect of grain orientation on device efficiency. Utilising the one-dimensional nature of ribbon transport the 2D simulation area is divided into multiple 1D ribbons, for which the individual contributions to current are calculated. The boundary conditions for transport along a given ribbon is determined by the space charge region (SCR) and the ribbon termination at either the back contact (BC) or a grain boundary. Therefore, there are two transport scenarios, namely SCR-BC and SCR-GB. The relative fraction of each will depend on the ribbon orientation, film thickness and grain size. For 1 μm diameter Sb2Se3 grains in a 3 μm thick film oriented along the ideal [001] direction only the SCR-BC transport mechanism can occur. However, for orientations with more than 20° deviation from this orientation, the SCR-GB transport mechanism takes the lead, and as a result of this, the efficiency drops rapidly from 19.69% to 6.81% for the non-passivated grain boundary. The efficiency can be improved to 9.28% by passivating the grain boundary (recombination velocity of 103 cm/sec); the passivation from the self-healing mechanism is expected to occur for all orientations above 20°. Although efficiency does not decrease as fast, high angles are undesirable because of their low efficiency. Li et al. have shown that growing Sb2Se3 thin-films with the ideal [001] orientation is a complex process, that is still under development. 2 However, for the commonly occurring non-ideal orientations, the possibility of grain boundary passivation through deep structural relaxation could offer a new approach to increasing Sb 2 Se 3 device efficiencies. In this work, a complementary strain analysis study on atomic resolution TEM experimental data is presented; the observed variation in the inter-ribbon distance is consistent with the published DFT theoretical work. References 1. McKenna, K. P. Adv. Electron. Mater. 7, 2000908 (2021). 2. Li, Z., et al. Nat. Commun. 10,125 (2019).

P14

Application of novel low-cost and transparent hole conductors with long-term stability in ultrasonic spray deposited Sb 2 S 3 -based solar cells Sreekanth Mandati 1 , Atanas Katerski 1 , Nimish Juneja 1 , Aiste Jegrove 2 , Aivars Vembris 3 , Vytautas Getautis 2 , Tatjana Dedova 1 , Malle Krunks 1 , Nicolae Spalatu 1 , Matteo Chiesa 1 , Smagul Karazhanov 4 and Ilona Oja Acik 1 1 Tallinn University of Technology, Estonia, 2 Kaunas University of Technology, Lithuania, 3 University of Latvia, Latvia, 4 Institute for Energy Technology (IFE), Norway Photovoltaic (PV) solar energy conversion is one of the leading technologies to meet present days’ energy demand and it is a green process, which is an important step towards pollution-free energy production. Among various applications of PV, building integrated PV is a major area wherein the solar cells are generally incorporated as windows and are required to be semi-transparent. In this scenario, efforts have been dedicated towards developing novel materials to obtain semi-transparent solar cells with reasonable efficiencies. It is also important to consider the costs associated with the materials and pertinent processes, materials abundance and their stability. Thin films solar cells based on Sb 2 S 3 are promising for semi-transparent applications owing to its superior optoelectronic properties, stability and availability of raw materials. However, though the transparency has been obtained in the absorber stage, the use of hole transport materials (HTM) like P3HT reduces the overall transparency of the solar cells while HTMs like Spiro-MeOTAD possess issues with long-term stability. Further, these conventionally used HTMs are very expensive to be considered for large scale manufacturing. In appreciation of the above, the present work proposes to explore novel, low-cost and transparent fluorene based thiophene containing HTMs for application in ultrasonic spray deposited Sb 2 S 3 solar cells. A series of HTMs like V808, V1385, and V1386, which particularly have better interaction with Sb 2 S 3 absorber are spin coated in the superstrate device configuration of Glass/FTO/TiO 2 /Sb 2 S 3 /HTM/Au wherein TiO 2 and Sb 2 S 3 are deposited using ultrasonic spray pyrolysis. Preliminary studies unveil the solar cells with novel HTM have yielded similar power conversion efficiencies compared to the ones with P3HT, indicating their efficacy. Further, the individual layer and device properties, and overall transparency of the solar cells stack are systematically characterized and the results will be discussed.

P15

Want to improve on structural disorder in Cu-based quaternary chalcogenides? Let’s look at the divalent cation! David Matzdorff 1 , Galina Gurieva 1 , Denis Cheptiakov 3 , Susan Schorr 1,2 1 Helmholtz-Zentrum Berlin für Materialien und Energie, Germany, 2 Institut für Geologische Wissenschaften, Germany, 3 Paul Scherrer Institute, Switzerland With the increasing demand for sustainable energy sources, the group of Cu-based chalcogenides stands out in the field of photovoltaic applications, because they consist of non-toxic and earth abundant elements. On top of that the related solar cells show excellent stability under environmental conditions. It was even possible to achieve a PCE of 13.2% [1]with CZTSSe-based solar cells (CZTSSe-Cu 2 ZnSn(S,Se) 4 ), however, CZTSSe absorbers face a major problem. The material show a low open circuit voltage (V oc ) and it has been established that the low V oc is attributed to the widespread Cu-Zn disorder (Cu Zn /Zn Cu ) in kesterite absorbers [2,3]. A complete replacement of Zn with Mn in the semiconductor could potentially solve this problem. For that reason, we studied the two related Cu 2 MnSnS 4 and Cu 2 MnSnSe 4 compounds. They are able to cover a bandgap range of 1.1-1.5 eV [4,5] and thus ideal for both single junction and potentially tandem solar cells. The bandgap energy is significantly controlled by crystal structure. Unfortunately, the data available for these materials in terms of in-depth structural analysis is very limited and urgently needs to be further explored. The kesterite-type materials (Cu 2 ZnSnS 4 , Cu 2 ZnSnSe 4 and CZTSSe) has been already studied in detail establishing the off-stoichiometry type model [6] to assess experimentally point defects and structural disorder (Cu-Zn disorder). This model was also applied here for the Cu 2 MnSnX 4 (X= S, Se) semiconductors. The structural analysis of Cu 2 MnSnS 4 and Cu 2 MnSnSe 4 by conventional X-ray diffraction (XRD) encounters difficulties because the distinct cation positions in the crystal structure are occupied by different electronically similar elements (Cu, Mn and Ge). Due to their similar atomic scattering factors they cannot be distinguished in the process of analyzing the XRD data. That’s why we performed neutron diffraction experiments on those compounds to make use of the very different neutron scattering length of Cu, Mn and Ge allowing to distinguish between them. We applied the average neutron scattering length analysis method [7] to determine the cation distribution in the unit cell, the basis to conclude on the crystal structure and structural disorder. We show that Cu 2 MnSnS 4 and Cu 2 MnSnSe 4 adopt the stannite-type crystal structure type which hinder the structural disorder observed in the Zn-containing counterparts References 1. Zhou, J. (2021). Nano Energy , 89 , 106405 2. Rey, G. (2014). Applied Physics Letters , 105 , 112106

3. Valentini, M. (2016). Applied Physics Letters , 108 (21), 211909 4. Beraich, M. (2020). Journal of Alloys and Compounds , 845 , 156216 5. Ramasamy, K. (2018). Chemical Communications , 54 , 11757–11760 6. Schorr, S. (2019). Journal of Physics: Energy , 2 , 012002 7. Schorr, S. (2011). Solar Energy Materials and Solar Cells , 95 , 1482–1488

P16

Improved stability and electrical properties in CsPbIBr 2 thin films through magnesium and acetate co-doping Ahmet Nazligul and Mingqing Wang University College London, United Kingdom The research interest on perovskite solar cells has increased substantially in the past 10 years as these solar cells have been breaking record after record. However, one persistent issue for perovskite solar cells that hinders their commercial availability has been their low stability. Fully-inorganic Cs-based perovskites have been developed as an alternative to hybrid perovskites since these perovskites are relatively more stable 1 . Still, one problem is that the stability is lower in low bandgap Cs-based perovskites compare to high bandgap Cs- based perovskites 2 . In this study we investigated the potential of CsPbIBr2 which is a relatively high bandgap perovskite 3 . We have co-doped CsPbIBr2 thin-films with magnesium and acetate through a simple solution based method. At the low doping levels of 0.5%, the thin-films shows improved crystal structure, less charge- recombination and prolonged film life while having minimal effect on the bandgap. In our opinion this method has a strong potential to increase the device efficiency and stability. References 1. Wanchun Xiang, Shengzhong (Frank) Liu and Wolfgang Tress; Energy Environ. Sci., 2021, 14, 2090-2113; DOI: 10.1039/ D1EE00157D 2. Riccardo Montecucco, Eleonora Quadrivi, Riccardo Po, Giulia Grancini; Adv. Energy Mater. 2021, 11, 2100672; DOI: 10.1002/aenm.202100672 3. Jyoti V. Patil, Sawanta S. Mali, and Chang Kook Hong; ACS Sustainable Chem. Eng. 2020, 8, 43, 16364–16371; DOI: 10.1021/acssuschemeng.0c06452

P17

Unravelling the impact of disorder on the electronic properties of mixed-metal chalcohalides Adair Nicolson 2 and Seán Kavanagh 1 1 Thomas Young Centre and Department of Chemistry, University College London, UK 2 Thomas Young Centre and Department of Materials, Imperial College London, UK Mixed-metal mixed-anion systems have seen a significant rise in interest as ‘perovskite-inspired materials’ as are expected to combine the excellent stability seen in metal chalcogenide solar cells with the well-known performance of hybrid halide perovskite solar cells. [1] Sn2 SbS 2 I 3 is a promising solution-processed photovoltaic absorber having achieved efficiency above 4% in initial devices. [2] Theoretical work predicts that the material family of A2 BCh 2 X 3 mixed-metal chalcohalides could also be ferroelectric, with Sn2 SbS 2 I 3 having strong lattice polarization and large dielectric constants. [3] However, this family has not been rigorously explored resulting in confusion in the literature regarding the structure of these materials, with some works observing disorder in room temperature crystals. [4] Without a proper description of the structure, prediction of the electronic properties cannot be accurately performed. Understanding the extent of the disorder in these systems is of key importance due to its tendency to quench favourable properties such as macroscopic polarisation. Using Density Functional Theory, Cluster expansion and Monte Carlo techniques, we have systematically examined the cation disorder in Sn2 SbS 2 I 3 for the first time and will discuss its likely impact on the potential for this material family to produce ferroelectric and photovoltaic devices. References 1. Nie, R.; Sumukam, R. R.; Reddy, S. H.; Banavoth, M.; Seok, S. I. Lead-Free Perovskite Solar Cells Enabled by Hetero- Valent Substitutes. Energy Environ. Sci. 2020 , 13 (8), 2363–2385. https://doi.org/10.1039/D0EE01153C. 2. Nie, R.; Lee, K. S.; Hu, M.; Paik, M. J.; Seok, S. I. Heteroleptic Tin-Antimony Sulfoiodide for Stable and Lead-Free Solar Cells. Matter 2020 , 3 (5), 1701–1713. 3. Kavanagh, S. R.; Savory, C. N.; Scanlon, D. O.; Walsh, A. Hidden Spontaneous Polarisation in the Chalcohalide Photovoltaic Sn 2 SbS 2 I 3 . Materials Horizons 2021 4. Doussier, C.; Moëlo, Y.; Léone, P.; Meerschaut, A.; Evain, M. Crystal Structure of Pb2SbS2I3, and Re-Examination of the Crystal Chemistry within the Group of (Pb/Sn/Sb) Chalcogeno-Iodides. Solid State Sciences 2007 , 9 (9), 792–803.

P18

Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34

www.rsc.org

Made with FlippingBook Learn more on our blog