Perovskiters

Perovskiters are a class of materials that adopt the perovskite crystal structure, typically with the formula ABX3, where A is an organic or inorganic cation, B is a metal cation, and X is a halide. In most high-performance perovskite solar cells, B is lead (Pb2+) and X is iodine or a mixed iodine/bromine. The A-site is often methylammonium (MA+), formamidinium (FA+), or cesium (Cs+). The three-dimensional ABX3 network consists of corner-sharing BX6 octahedra, with the A-site cation occupying the spaces between them. The structure permits a direct bandgap and strong light absorption, enabling solution processability.

Perovskites gained prominence after 2009 for solar cells, achieving rapid increases in efficiency from around 3% to over 25% in the mid-2020s. Their properties include tunable bandgaps through halide composition, long charge-carrier diffusion lengths, and high defect tolerance. Common device architectures include planar and mesoporous structures, with processes based on spin coating or scalable methods such as slot-die coating.

Challenges center on stability and environmental impact. Moisture, oxygen, heat, and UV light can degrade perovskites, and lead toxicity raises safety concerns. Researchers address these issues with mixed-cation and mixed-halide formulations, more robust encapsulation, and the development of quasi-2D or entirely lead-free variants, though the latter often trade performance for stability. Applications extend beyond solar cells to light-emitting diodes, photodetectors, and lasers. Ongoing work focuses on scalable manufacturing, long-term operational stability, and addressing lifecycle environmental considerations.