Polymer-POSS composites as hosts for Luminescent Solar Downshifters Helen Tunstall-Garcia , Rachel Evans, Bethan L. Charles University of Cambridge, UK Solar power has great promise as a renewable energy source. However, current photovoltaic (PV) technologies suffer from losses such as thermalisation and recombination, limiting their efficiencies. Spectral converters can overcome these problems by converting incident sunlight into wavelengths that better match the spectral response of an attached PV cell, for example by converting UV to visible light through luminescence downshifting (LDS). 1 These layers are deposited on top of the solar cell and thus must withstand significant weathering. While previous work has investigated nano-reinforced protective coatings with potential for solar cells; these materials are yet to be adapted LDS host materials. In this work, we investigate the effect of polyhedral oligomeric silsesquioxanes (POSS) as additives in a polyethylene-co-glycidyl methacrylate (PEGMA) host, both in the presence and absence of a fluorescent dye (Coumarin 1). POSS nanoparticles have shown great potential as thermal and mechanical reinforcements in polymeric materials, 2 and the blended material is easily processable and tunable. Furthermore, the properties of light-emitting materials can be improved by the introduction of POSS, which reduces aggregation-caused quenching and increases photostability. 3 The host properties are assessed by studying the compatibility and polymer properties of a series of POSS-PEGMA hybrid composite films without Coumarin 1. In order to examine the performance as LDS layers, the optical properties of the Coumarin 1-doped composite films are investigated through microscopy, transmittance, steady-state and time-resolved photoluminescence. The knowledge gleaned through these studies will enable us to identify the optimum POSS reinforcement loading to obtain highly robust and efficient luminescent downshifters.
References 1. McKenna, B.; Evans, R. C. Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices. Mater. 2017 , 29 (28), 1606491. 2. Zhou, H.; Ye, Q.; Xu, J. Polyhedral Oligomeric Silsesquioxane-Based Hybrid Materials and Their Applications. Chem. Front. 2017 , 1 (2), 212–230. 3. Tunstall-Garcia, H.; Charles, B. L.; Evans, R. C. The Role of Polyhedral Oligomeric Silsesquioxanes in Optical Applications. Photonics Res. 2021 , 2 (6), 2000196.
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