The Prospects and Challenges for Ambi‐polar Vacancy‐Ordered Double‐Perovskite Cs₂SnI₆ Toward Realization of High‐Efficiency Air‐Stable Solar‐Cells

Abstract

The rapid advancements in material research for lead‐free inorganic metal halide perovskites have fuelled the pathway to design environmentally‐benign solar‐cells to cater the energy requirements for future generations. The vacancy‐ordered double perovskite Cs2SnI6 with an optimum band‐gap (∽1.3 eV), high absorption coefficient (∽105 cm‐1), ambi‐polar charge carrier transport, high structural and compositional stability coupled with simple cost‐effective solution‐based synthesis techniques seems to be an excellent candidate to design air‐stable high‐efficiency solar‐cell based applications. The review focusses on the structure‐property relationship in Cs2SnI6; and its critical dependency on growth precursors, conditions and methods. The recent advancements in material and additive engineering to obtain phase‐pure uniform continuous smooth Cs2SnI6 films; and myriad methods to modulate its opto‐electronic properties are summarized. The nature, origin and type of charge‐carriers in intrinsic and doped Cs2SnI6 is extensively discussed. The application of Cs2SnI6 in dye sensitized solar‐cell (DSSC) and planar perovskite solar‐cell (PSC) configurations are critically reviewed; and its recent progress and challenges to achieve ultimate theoretical Shockley‐Queisser limit of 30‐33% is presented. The recent experimental findings on the stability and performance of Cs2SnI6‐based solar‐cells under ambient and controlled conditions would be discussed to highlight its feasibility for the design and development of air‐stable high‐efficiency solar‐cells.This article is protected by copyright. All rights reserved.