In recent years, inorganic CsPbBr3-based perovskites have accomplished considerable progress owing to their superior stability under harsh humid environment.

Since the booming research on perovskite solar cells (PSCs), organic–inorganic hybrid halide perovskites have triggered widespread research attention. This is seen in the unprecedented improvement of the power conversion efficiency (PCE) from an initial 3.8% to a remarkable 25.5%. Despite the fascinating improvement in PCEs, the toxicity of the detrimental lead element is a major limiting factor that hampers the commercialization prospect of lead‐based materials. Extensive efforts have been dedicated to the progress of lead‐free, stable, and ecofriendly perovskite materials for green‐energy applications. Recently, double‐halide Cs2SnI6 perovskite emerged as a star material due to its favorable optoelectronic properties, stable nature, and environmental friendliness. Thus, an in‐time review to recapitulate the recent advances of Cs2SnI6 is critical to provide viable theoretical and experimental strategies for synergic optimization of perovskite films. Herein, the theoretical and experimental understandings of the properties of Cs2SnI6 are summarized and the different fabrication methodologies and their influences on the properties of Cs2SnI6 are discussed. The application potential of Cs2SnI6 is further reviewed and the limiting factors that influence the performance of Cs2SnI6 devices are highlighted. In the end, prospective research directions to improve the optoelectronic properties are presented for developing efficient Cs2SnI6 devices.

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Summary Cs2SnI6 has recently been reported as a promising material to replace Pb‐based perovskite materials due to its appropriate optical and electrical properties as well as high stability in the ambient environment. Here, the study focuses on introducing different types of reactants to form highly stable Cs2SnI6 films via a modified two‐step process. The structural analysis was examined using the X‐ray diffraction measurements and lattice strain and average crystallite size were calculated by the Williamson hall method. All the prepared films showed excellent phase stability at 210°C with no major CsI impurity peak. Adding excess I2 with SnI4 at 225°C resulted in inhibiting the decomposition of the film. Raman measurements revealed the presence of three first‐order modes at 78, 92, 126 cm−1, and a higher mode at 248 cm−1, respectively. The UV‐vis results confirm the direct semiconductor nature of Cs2SnI6 with bandgap ranging from 1.31‐1.37 eV. The iodine‐rich preparation of the films resulted in improved photoluminescence and high hole mobility of 329 (cm2V−1 s−1). The present work will provide useful guidance in the preparation protocol of Cs2SnI6 perovskite solar cells.

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In the past decade, organic–inorganic halide perovskites (OIHPs) perovskite solar cells (PSCs) have received gigantic research attention owing to their prompt development in power conversion efficiency (PCE) from the initial 3.8% for the first prototype in 2009 to the present state‐of‐the‐art value of 25.5%. However, due to the weak‐bonded organic components in the hybrid crystal structure, the intrinsic chemical instability of OIHPs persuaded by humidity, ultraviolet light, and heat remain a challenging issue for them to meet industrialization‐specific requirements. Parallel to the flourishing of OIHPs, the progress of inorganic cesium‐based metal halide PSCs (CsPbX3, X = I, Br, and mixed) is hastening with PCEs over 20%. Due to its excellent stability under thermal and high humidity conditions, CsPbI2Br is one of the most fascinating inorganic perovskites and a notable research hotspot in the field of perovskite photovoltaics (PV). Herein, recent developments of CsPbI2Br‐based PSCs including the optoelectronic properties, processing methods for preparing CsPbI2Br films, stability of devices, and efficiency improvements are reviewed and deliberated. Finally, cutting‐edge engineering approaches for optimizing the PV performance are discussed and new challenges and perspectives for future research in this field are recognized.

The preparation route has striking impacts on the morphology and photovoltaic performance of the solar cells, and the development of a feasible preparation strategy to make such a technology applicable to industry is of utmost significance. Compared with solution processing, the vapor deposition strategy has been demonstrated as an effective way to fabricate compact and uniform perovskite thin films with excellent versatility and controllability. While the vast majority of literature emphasizes solution processing as the deposition method for perovskite solar cells (PSCs), vapor‐deposited PSCs are closing the performance gap with numerous research reports of efficiencies above 20%. Thus, an in‐time review is critical to summarize the fundamentals of vapor‐based deposition strategies to evaluate their real potential and put challenges into perspective. Herein, various vapor deposition routes for the preparation of all‐inorganic perovskite films and solar cells are thoroughly addressed. Moreover, the critical factors such as deposition temperature, film thickness, substrate temperature, and annealing conditions that impact the film quality and photovoltaic performance of the perovskite are reviewed. In the end, conclusion and future possibilities of the vapor deposition processes are presented, which will offer constructive guidance for the large‐scale fabrication of solar cells.

In recent years, the organic-inorganic perovskite materials have revolutionized the Photovoltaic industry with highly efficient power conversion devices accompanied by a high growth rate. However, these devices experience major environmental and stability issues that hinder their true potential. More recently, a rarely studied perovskite material Cs2SnI6 is gaining enormous attention due to its superior stability and suitable bandgap. In this work, we developed a modified two-step process to prepare uniform Cs2SnI6 films, and the influence of the reaction conditions on the properties is explored. The structural, morphological, optical, and electrical properties of the prepared films were investigated using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV–vis spectrometer, photoluminescence, and Hall Effect measurements, respectively. Phase stability and morphology of the films are improved with optimizing the reaction conditions. The results confirm the n-type semiconductor nature of Cs2SnI6 with bandgap ranging from 1.29 eV to 1.42 eV with maximum carrier mobility of 425 cm2 V−1 s−1. The present study will further provide potential research directions in improving the device efficiency of air-stable Cs2SnI6 perovskite solar cells.