Realizing Enhanced Efficiency in Nonhalogen Solvent Processed Ternary Polymer Solar Cells by Incorporating Compatible Polymer Donor

Abstract

Ternary polymer solar cells (PSCs) with three photoactive components can potentially enhance the photovoltaic performance compared with binary devices. Meanwhile, the additional third component also can act as a recombination center or a morphological trap within the host binary system, leading to overall decrease of photovoltaic performance. Therefore, it is challenging to rationally select a miscible component for the host binary blend to achieve a well‐developed morphology of the ternary blend. Especially, it is more comprehensive to fine‐tune the morphology of the ternary blend via nonhalogen solvents processing. In this work, a new polymer donor PBDB‐BT is reported as the third component for PBDB‐TS:ITIC blend. PBDB‐BT shows complementary absorption spectrum and similar low‐lying HOMO level with PBDB‐TS. Building the ternary PSCs by using o‐xylene as processing solvent, a higher power conversion efficiency (PCE) of 10.26% was realized compared to the control device (PCE = 9.81%). In‐depth studies reveal that the enhanced PCE of the devices resulted from the improved charge dissociation, suppressed bimolecular combination losses, and well‐balanced charge‐carrier mobilities of the ternary blend. The results demonstrate that constructing ternary blend via incorporation of structurally similar polymer donor is a promising approach to improve the efficiency of nonhalogen solvent processed PSCs.