Exotic Structural and Optoelectronic Properties of Layered Halide Double Perovskite Polymorphs

Abstract

Discovering new types of layered perovskites has great importance for designing novel optoelectronic devices. In this article, combining first‐principle calculations with global structure searching, it is found that Rb4SnSb2Br12, a typical halide double perovskite, can unexpectedly possess fertile low formation‐energy polymorphs holding van de Walls (vdW) layered structures. Consequently, these polymorphs can be effectively classified into 12 types according to their local octahedral motifs, exhibiting a wide range of bandgap covering the visible spectrum. Interestingly, the structure‐dependent bandgap in these polymorphs can be well understood by developing a simple machine learning model. Moreover, as a layered system, the optoelectronic properties of Rb4SnSb2Br12 can be effectively tuned by the layer thickness, and both type‐I and type‐II band alignment can be achieved in single‐compound Rb4SnSb2Br12 heterojunctions. Finally, it is suggested that the Sn‐moderate condition can be considered to grow intrinsic p‐type Rb4SnSb2Br12 with lower defect density. Those findings not only provide a promising material system for designing the vdW tandem solar cell, but also offer a new opportunity to achieve exotic optoelectronic applications in a single‐phase layered perovskite compound.

An Efficient ab Initio Scheme for Discovering Organic–Inorganic Hybrid Materials by Using Genetic Algorithms

“…Notably, the crystal structures of inorganic materials can be predicted by a combination of first-principles calculations and genetic algorithms with only an input of their compositions. − The genetic algorithms are metaheuristics inspired by the process of natural selection. These algorithms mimic Darwinian evolution and use natural selection of the fittest and variation operators, such as genetic heredity and mutations.…”

Self-energy correction and numerical simulation for efficient lead-free double perovskite solar cells

“…6 However, the commercialization of PSCs is not progressing smoothly nowadays, mainly due to lead toxicity and instability. 7,8 Therefore, the development of lead-free or low toxicity, and good stability perovskite materials, is a hot spot. Gradually researchers have used group 2A or group 4A inorganic cations instead of Pb 2+ , but unfortunately, the bivalent cations easily oxidize into more stable tetrad ions, 3,9 making it difficult to use them.…”