Coordination-induced bridging polymer enables favorable interface compatibility and vertical phase distribution in efficient organic solar cells

Abstract

The vertical phase distribution of the active layer and the effective interface contact between the active layer and transport layer are crucial for the photovoltaic performance of organic solar cells (OSCs). We synthesized an α-diketone-based polymeric donor PBTO, which was applied to bridge the copper(I) thiocyanate CuSCN and the active layer in OSCs. PBTO exhibited perfectly complementary absorption with those of PM6 and BTP-eC9, and the poor solubility of BPTO in toluene renders it a layer. The coordination of contact between the PBTO and the CuSCN surface enhanced the binding strength of both materials. Moreover, due to closer surface energy, PBTO can induce a favorable vertical phase distribution in the upper active layer to achieve a p-i-n-like configuration, effectively reducing carrier recombination losses. Through the multiple roles of the bridging agent PBTO, we achieved a wide range of photon capture, efficient charge transport, and reduced carrier recombination. Ultimately, the device power conversion efficiency reached 19.02%. Our research results present a strategy for synergistically improving charge transport and optimizing vertical phase distribution in OSCs, offering new insights into the polymer molecular design.