Tin-doped methylammonium lead chloride perovskites yield improved performance

Methylammonium lead halide perovskite crystals have a wide range of promising applications from solar cells to optical photodetectors. However, some anticipate that the presence of lead in these materials may hinder their large-scale commercialization. This has motivated researchers to look for ways to reduce lead in the perovskites without compromising the performance.

Sarkar et al. report an isostructural series of tin-doped methylammonium lead chloride perovskites with better crystallinity and enhanced absorption toward longer wavelengths. Owing to enhanced chemical bonding, the chloride perovskites are significantly more resistant to degradation under ambient conditions than their I/Br counterparts. This gives them clear advantages for many optoelectronic applications. This group is the first to successfully substitute tin for lead in this material.

“In this work, we have provided several characteristics of undoped and tin-doped methylammonium lead chloride compounds for better understanding of doping effects on the host perovskite,” said author S.K. Tripathy. “This paper offers a new reference for exploring the use of tin-doped methylammonium lead chloride perovskite materials in optoelectronic devices.”

The reduction in lead content is accompanied by several unexpected side benefits, including improved crystallinity and enhanced longer-wavelength absorption as the tin content was increased. The absorption edge is reduced from 2.93 eV to 2.83 eV when one-third of the lead was replaced with tin.

Thermogravimetric studies of their samples also showed that tin doping improved the thermal stability of the perovskites up to 20% tin, but begins to decrease when the tin content exceeds 33%. These assure the reliability and the correctness of the approach.

The group hopes their research will inspire future work and is planning to explore other alternatives for lead in methylammonium halide perovskites.

Source: “Impact of Sn doping on methylammonium lead chloride perovskite: An experimental study,” by P. Sarkar, A. Srivastava, S. K. Tripathy, K. L. Baishnab, T. R. Lenka, P. S. Menon, F. Lin, and A. G. Aberle, Journal of Applied Physics (2020). The article can be accessed at https://doi.org/10.1063/1.5133457 .