Low-cost Cu-based inorganic hole transporting materials in perovskite solar cells: Recent progress and state-of-art developments

Perovskite solar cells (PSCs) are rapidly approaching as promising processes toward efficient energy harvesting technologies. High cost and low environmentally stable organic hole transporting materials (HTMs) are the main hurdles in their commercial realization. Perovskite community is actively looking for inorganic HTMs which will potentially yield into a pragmatic solution. Cu-based materials, e.g. Cu-based oxides, halides, and chalcogenides exhibit features like low production cost, suitable band alignment, and high hole mobility Due to these properties, Cu-based materials are being explored as potential HTMs in PSCs. Significant efforts are contributed toward using low-cost Cu-based materials because of high chemical stability, high carrier mobility, low-cost and the possibility of developing a very simple technique. The photo-physical properties, e.g. optical electronic structure, valence band engineering, and carrier mobility are briefly discussed. Detailed insights toward understanding the development of Cu-based HTMs along with their possible pragmatic commercialization aspects are presented. This article highlights the utilization of Cu-based chalcogenide HTM and role of ternary Cu-based chalcopyrite, Pnma ternary chalcogenides, sulvanite and oxychalcogenides in the field of PSC with a brief idea about tailoring their optoelectronic properties. This article will significantly help the community toward the engineering of novel Cu-based HTMs for possible commercialization of PSC technology.