Recent progress of inorganic hole transport materials for efficient and stable perovskite solar cells

Abstract With the power conversion efficiency (PCE) surpassing 25%, the eye‐catching and promising perovskite materials have proved to be potential competitors in photovoltaic field. Till now, massive efforts have been invested into this blooming flower to further raise its efficiency approaching the Shockley‐Queisser limit (SQ limit) and improve its stability for prolonging effective operation life. In details, various methods including component engineering, structure optimization and interfacial treatment have been used for realizing efficient and stable devices. Especially, the charge transport layers usually play critical roles in effective extraction and transportation of charge carriers. Compared with organic charge transport materials, inorganic materials generally demonstrate excellent stability due to their superior film qualities and inert chemical properties. Moreover, low cost, high charge mobility and material stability have been proved for inorganic electron and hole transport materials. This review summarizes the general progress of different inorganic hole transport materials in perovskite solar cells of recent years for better acquaintance of their contribution in efficient and stable devices. The discussions about performance improvement in the future directions are also provided.