Topology-Engineered Coordination Polymers for Enhanced Hole Transport in Organic Solar Cells

The commercialized PEDOT:PSS is the most commonly used hole-transporting material in organic solar cells (OSCs) due to its solution processability, good transparency, and universality across different material systems. However, its relatively shallow work function (WF) and unsatisfactory longitudinal conductivity constrain the device performance. Here, we develop three coordination polymers (CPs) with adjustable spatial topologies based on copper iodide (CuI) and 2,7-di(pyridine-4-yl)acridine (DPA), and reveal the mechanism by which topology-engineered regulation mediates the properties of PEDOT:PSS and the active layer as well as OSC performance. Through the functions of coordination-induced separation and stacking enhancement effect induced by topology, the blended CPs-PEDOT:PSS films exhibit better π-π stacking, higher longitudinal conductivity and a deeper WF level, facilitating carrier dynamics and reducing interfacial voltage loss. The resulting champion device based on the binary active layer exhibits a high efficiency of over 20%. This work demonstrates the application potential of topology-engineered CPs as hole-transporting materials and provides a rational strategy to construct robust interlayers.