Abstract
Trap-assisted charge recombination is one of the primary limita-tions of restricting the performance of organic solar cells.However,effectively reducing the presence of traps in the photoactive layer remains challenging.Herein,wide bandgap polymer donor PTzBI-dF is demonstrated as an effective modulator for enhancing the crystallinity of the bulk heterojunction active lay-ers composed of D18 derivatives blended with Y6,leading to dense and ordered molecular packings,and thus,improves photoluminescence quenching properties.As a result,the photovoltaic devices exhibit reduced trap-assisted charge recom-bination losses,achieving an optimized power conversion efficiency of over 19％.Besides the efficiency enhancement,the devices comprised of PTzBI-dF as a third component simultaneously attain decreased current leakage,improved charge carrier mobilities,and suppressed bimolecular charge recombination,leading to reduced energy losses.The advanced crystalline structures induced by PTzBI-dF and its characteristics,such as well-aligned energy level,and complementary absorption spectra,are ascribed to the promising performance improvements.Our findings suggest that donor phase engineering is a feasible approach to tuning the molecular packings in the active layer,providing guidelines for designing effective morphology modulators for high-performance organic solar cells.
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