Ether-Soluble Cu53 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 equivalent to CtBu)(20)Cl2H18](+) (Cu-53), which is the largest Cu-I/Cu-0 cluster reported to date. Cu powder and Ph2SiH2 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@Cu10Cl2@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.