Lead‐Free Cs₂SnI₆ Perovskites for Optoelectronic Applications: Recent Developments and Perspectives

Abstract

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.

Mapping the Real-Time Vibrational Infrastructure of Cs2SnI6 Nanocrystals through Coherent Phonon Dynamics

“…It has emerged as a potential light-absorbing layer in photovoltaic (PV) devices because of its optimal energy band gap and high absorption coefficient. Photoconversion efficiency (PCE) exceeding 10% has already been reported for Cs 2 SnI 6 -based solar cells. − Indeed, it has also illustrated exotic candidature as a hole transporting layer. − Aside from the potent candidature displayed for solar cell applications, thermo-electrics is another such classified field where Cs 2 SnI 6 by virtue of its low thermal conductivity ( k ) has witnessed commendable success. , Such low magnitudes of “ k ” have often been linked to vibrational chaos stemming from anharmonicity in the lattice dynamics. − Even more, recent literature has attributed the photoconversion efficiencies of PV devices to lattice anharmonicity. − …”

The Fabrication of Lead‐Free Cs2SnI6 Perovskite Films Using Iodine‐Rich Strategy for Optoelectronic Applications

“…Due to its potential environmental friendliness and excellent stability, the defect perovskite Cs 2 SnI 6 has recently garnered considerable attention as a new photovoltaic superstar. [26][27][28] The oxidation state of Sn 4þ and the presence of the strong Sn─I covalent bond in Cs 2 SnI 6 may provide a solution to the stability challenges. Cs 2 SnI 6 has a bandgap of 1.26-1.62 eV, a carrier mobility of 3-510 cm 2 V À1 s À1 , and a high absorption coefficient of 10 5 cm À1 .…”

A facile one‐step solution synthesis of Cs 2 SnI 6−x Br x using less‐toxic methanol solvent for application in dye‐sensitized solar cells

“…13,15,[19][20][21][22][23][24] Recent emphasis has been focused on a 0D-Cs 2 SnI 6 perovskite owing to its non-toxicity and superior endurance under external environments. [25][26][27][28][29][30][31] In comparison to CsSnI 3 , Cs 2 SnI 6 is composed of a [SnI 6 ] 2À octahedral structure and exhibits high carrier mobility when doped as an n-type semiconductor. Additionally, Cs 2 SnI 6 has an optimum bandgap of 1.26 to 1.62 eV for photovoltaic applications.…”