Enhancing photovoltaic efficiency in BDTF-based donor polymer solar cells: insights from structural modifications

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Polymer solar cells (PSCs) have gained attention for their flexibility, low cost, lightweight properties, and suitability for large-scale production of renewable energy. Typically, PSCs utilize bulk heterojunction (BHJ) active layers composed of blended electron donor and acceptor materials. Improving the efficiency of PSCs involves developing new donor polymers through precise monomer design and optimizing side-chain engineering to enhance properties such as solubility, molecular packing, and electron affinity. Fluorinated benzodithiophene (BDTF) and thiophene-dione-based acceptor units have demonstrated exceptional performance in non-fullerene PSCs with Y6BO as the acceptor. This study focuses on incorporating a linear alkyl chain, 5-((4,5-dioctylthiophen-2-yl)methylene)-4H-cyclopenta[c]thiophene-4,6(5H)-dione (TIND-DOT), into BDTF-based polymers to evaluate their photovoltaic properties using devices structured as ITO/ZnO/TIND-DOT-BDTF:Y6BO/MoO3/Ag giving maximum PCE of 6.55%. The research explores D-A combinations to assess their impact on optoelectronic and photovoltaic performance, highlighting the potential of modifying thiophene-dione core units as acceptors in promising donor materials for advancing PSCs.