Ether‐Soluble Cu 53 Nanoclusters as an Effective Precursor of High‐Quality CuI Films for Optoelectronic Applications

An effective strategy is developed to synthesize high‐nuclearity Cu clusters, [Cu 53 (RCOO) 10 (C≡CtBu) 20 Cl 2 H 18 ] + ( Cu 53 ), which is the largest Cu I /Cu 0 cluster reported to date. Cu powder and Ph 2 SiH 2 are employed as the reducing agents in the synthesis. As revealed by single‐crystal diffraction, Cu 53 is arranged as a four‐concentric‐shell Cu 3 @Cu 10 Cl 2 @Cu 20 @Cu 20 structure, possessing an atomic arrangement of concentric M 12 icosahedral and M 20 dodecahedral shells which popularly occurs in Au/Ag nanoclusters. Surprisingly, Cu 53 can be dissolved in diethyl ether and spin coated to form uniform nanoclusters film on organolead halide perovskite. The cluster film can subsequently be converted into high‐quality CuI film via in situ iodination at room temperature. The as‐fabricated CuI film is an excellent hole‐transport layer for fabricating highly stable CuI‐based perovskite solar cells (PSCs) with 14.3 % of efficiency.