Coordination Strategy Driving the Formation of Compact CuSCN Hole‐Transporting Layers for Efficient Perovskite Solar Cells

Abstract

The preparation of a high‐quality CuSCN thin film is very important to guarantee its efficient performance in an electronic device. Herein, a coordination strategy is reported for the formation of a highly compact CuSCN hole‐transporting layer by retarding fast crystallization via constructing intermediate adducts, and investigated its application for perovskite solar cells (PSCs). Specifically, the strong coordination bond between CuSCN and pyridine derivate ligands results in the formation of a stable intermediate phase, which is further converted to compact CuSCN layers under thermal annealing. The configuration of the intermediate phase is demonstrated to be crucial for the subsequent assembly of high‐quality CuSCN layers and results in an improved performance of the devices. CuSCN thin films crystallized from an intermediate adduct, CuSCN‐(Cl‐Py), with a rippled sheet configuration show an exceptional surface uniformity and high hole mobility, which facilitates efficient hole extraction and suppresses charge recombination in PSCs, resulting in an enhanced device efficiency of 19.19%. That is the highest value of the inverted planar PSCs using CuSCN as a hole‐transporting layer to the best of the authors’ knowledge. This novel coordination strategy can be expected to be used in the preparation of other inorganic charge transporting materials for electronic devices.