Dissolution-Tailored Electrodeposition of High-Mobility Cu2o Transport Layers Beyond Conventional Methods

Abstract

As a fundamental element of perovskite solar cells (PSC), hole transport materials (HTM) must exhibit high carrier mobility, structural stability, and high film-forming quality. Cu2O, an inorganic compound and an efficient semiconductor, is regarded as a promising substitute for organic HTMs. In this study, the bidirectional pulsed (BP) electrodeposition technique was utilized for the fabrication of Cu2O thin films, with the objective of surmounting the constraints imposed by conventional direct current (DC) electrodeposition. The issues of Cu2+ impurity accumulation, grain disorder and high roughness, which are caused by unidirectional deposition, can be overcome by the addition of a periodic dissolution process. The dynamic equilibrium of the deposition-dissolution-redeposition cycle is accomplished by regulating the forward and reverse voltages on the basis of bidirectional pulses, yielding films with enhanced purity (79.22% Cu+ vs 60.32% DC) and (100) crystal orientation. The optimized films demonstrate superior carrier mobility (46.14 vs 42.12 cm2/V·s) and density (9.06 vs 8.09×1021 cm-3) with 10% lower resistivity (1.62 vs 1.73×10-5 Ω/cm). Structural analyses reveal enhanced grain uniformity and atomically smooth surfaces (Ra < 5.00 nm), coupled with 92% visible-light transmittance. The findings of this study demonstrate that BP electrodeposited Cu2O is a viable HTM candidate for PSC.

Keywords: Cuprous oxide, Bidirectional pulsed electrodeposition, Crystal orientation selectivity, Crystals dissolved