Alkoxybenzothiadiazole-Based Fullerene and Nonfullerene Polymer Solar Cells with High Shunt Resistance for Indoor Photovoltaic Applications

We synthesized three semicrystalline polymers (PTTBTBO, PDTBTBO, and P2FDTBTBO) by modulating the intra- and intermolecular noncovalent Coulombic interactions and investigated their photovoltaic characteristics under various light intensities. Low series (Rs) and high shunt (Rsh) resistances are essential prerequisites for good device properties under standard illumination (100 mW cm–2). Considering these factors, among three polymers, PDTBTBO polymer solar cells (PSCs) exhibited the most desirable characteristics, with peak power conversion efficiencies (PCE) of 7.52 and 9.60% by being blended with PC71BM under standard and dim light (2.5 mW cm–2), respectively. P2FDTBTBO PSCs exhibited a low PCE of 3.69% under standard light due to significant charge recombination with high Rs (9.42 Ω cm2). However, the PCE was remarkably improved by 2.3 times (8.33% PCE) under dim light, showing negligible decrease in open-circuit voltage and remarkable increase in fill factor, which is due to an exceptionally high Rsh...