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, [Cu₅₃ (RCOO)₁₀ (C≡CtBu)₂₀ Cl₂ H₁₈ ]⁺ (Cu₅₃ ), which is the largest Cu^I /Cu⁰ cluster reported to date. Cu powder and Ph₂ SiH₂ are employed as the reducing agents in the synthesis. As revealed by single-crystal diffraction, Cu₅₃ is arranged as a four-concentric-shell Cu₃ @Cu₁₀ Cl₂ @Cu₂₀ @Cu₂₀ structure, possessing an atomic arrangement of concentric M₁₂ icosahedral and M₂₀ dodecahedral shells which popularly occurs in Au/Ag nanoclusters. Surprisingly, Cu₅₃ 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.