Benzotriazole-based Polymer Acceptors with Precise Structures for All-polymer Solar Cells

In this contribution,two polymer acceptors (PT1-gamma and PT1-delta) based on benzotriazole (BTz) were de. signed and synthesized by regulating the polymerization sites. The effects of polymerization sites on the optical absorption, electrochemical energy levels, charge carrier mobility, and device performance of all-polymer solar cells (all-PSCs) were comprehensively investigated. Compared to PT1-delta, the polymer PT1-gamma exhibited narrower optical bandgap and higher electron mobility. As a result, the PT1-gamma-based all-PSC achieved a promising power conversion efficiency (PCE) of 11.92% with an open-circuit voltage of 0.89 V, a high short-circuit current density of 21.25 mA/cm(2), and a fill factor of 0.63 when blended with PBDB-T, which is higher than 9.68% of the all-PSC based on PT1-delta. This work demonstrates that the polymerization site has a very significant effect on the optoelectronic properties of benzotriazole-based polymer acceptors. Therefore, regulating the polymerization sites of monomers is an effective design strategy for the development of high-performance polymer acceptors.