Improve electro-conductive dendritic-co-polymers as donor materials for organic solar cells Morongwa E. Ramoroka 1 , Emmanuel I. Iwuoha 2 , Samantha Douman 1 1 Department of Chemistry, University of Cape Town, South Africa, 2 SensorLab, (University of the Western Cape Sensor Laboratories), Cape Town, South Africa In this work, dendritic thiophene and N-methylpyrrole functionalized poly(3-hexylthiophene-2,5-diyl) (P3HT) derivatives were synthesized using chemical oxidation polymerization. After synthesis of dendritic co-polymers, the properties of the resulting co-polymers were compared with those of linear P3HT as reference. Dendritic co-polymers were characterized by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), ultraviolet-visible spectroscopy (UV-Vis), scanning electron microscope (SEM), photoluminescence and electrochemical methods. FTIR spectra confirmed new imine bands, SEM showed change in morphology, decrease in optical bandgaps was confirmed using UV-Vis, CV revealed decrease in LUMO energy gap values, and EIS confirmed an increase in conductivity compared to P3HT. In addition, organic solar cells (OSCs) based on dendritic co-polymers performed better than P3HT based device. EIS and Tafel plots confirmed a reduction in charge recombination and increase in charge transport for dendritic co-polymers devices. References 1. Mdluli, S.B., Ramoroka, M.E., Yussuf, S.T., Modibane, K.D., John-Denk, V.S. and Iwuoha, E.I., 2022. π-Conjugated polymers and their application in organic and hybrid organic-silicon solar cells. Polymers , 14 , p.716. 2. Djoumessi Yonkeu, A.L., Ndipingwi, M.M., Tovide, O.O., Ramoroka, M.E., Ikpo, C. and Iwuoha, E.I., 2022. Microscopic, Spectroscopic, and Electrochemical Characterization of Novel Semicrystalline Poly (3-hexylthiophene)-Based Dendritic Star Copolymer. Polymers , 14 , p.4400. 3. Memela, M., Feleni, U., Mdluli, S., Ramoroka, M.E., Ekwere, P., Douman, S. and Iwuoha, E., 2020. Electro ‐ photovoltaics of Polymer‐stabilized Copper–Indium Selenide Quantum Dot. Electroanalysis, 32, pp.3086-3097. 4. Ramoroka, M.E., Mdluli, S.B., John-Denk, V.S., Modibane, K.D., Arendse, C.J. and Iwuoha, E.I., 2020. Synthesis and photovoltaics of novel 2, 3, 4, 5-tetrathienylthiophene-co-poly (3-hexylthiophene-2, 5-diyl) donor polymer for organic solar cell. Polymers, 13, p.2. 5. Ramoroka, M.E., Mdluli, S.B. and John-Denk, V.S., 2022. Synthesis and reactivities of conducting hexathienylbenzene-co- poly (3-hexylthiophene) star-branched copolymer as donor material for organic photovoltaic cell. Frontiers in Materials, 9, p.856008.
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