Balanced Charge Transport Optimizes Industry‐Relevant Ternary Polymer Solar Cells

Bulk heterojunction polymer solar cells based on a novel combination of materials are fabricated using industry‐compliant conditions for large area manufacturing. The relatively low‐cost polymer PTQ10 is paired with the nonfullerene acceptor 4TIC‐4F. Devices are processed using a nonhalogenated solvent to comply with industrial usage in absence of any thermal treatment to minimize the energy footprint of the fabrication. No solvent additive is used. Adding the well‐known and low‐cost fullerene derivative PC 61 BM acceptor to this binary blend to form a ternary blend, the power conversion efficiency (PCE) is improved from 8.4% to 9.9% due to increased fill factor (FF) and open‐circuit voltage ( V OC ) while simultaneously improving the stability. The introduction of PC 61 BM is able to balance the hole–electron mobility in the ternary blends, which is favourable for high FF. This charge transport behavior is correlated with the bulk heterojunction (BHJ) morphology deduced from grazing‐incidence wide‐angle X‐ray scattering (GIWAXS), atomic force microscopy (AFM), and surface energy analysis. In addition, the industrial figure of merit (i‐FOM) of this ternary blend is found to increase drastically upon addition of PC 61 BM due to an increased performance–stability–cost balance.