The photovoltaic performance of halide double perovskites (see picture) has been limited due to the large and/or indirect bandgap of the presently known materials. However, their applications extend beyond outdoor photovoltaics, as halide double perovskites exhibit properties suitable for memory devices, indoor photovoltaics, X-ray detectors, light-emitting diodes, temperature and humidity sensors, photocatalysts, and many more. Given that the halide double perovskites contain two metals instead of one, this class of materials offers a huge variety of compositions, where in principle any combination should be possible, provided that the geometric constraints of the structure (tolerance factor and the octahedral factor) are satisfied.

Inspired by the work of Bartelet al. (*Sci. Adv. 2019, 5:eaav0693*), the aim of the project is to theoretically explore which combination of metals are allowed to form novel double perovskite compositions that satisfy both the tolerance and octahedral factor. Analogous calculations will be performed while maintaining a constant set of metals and substituting the halide with a mixture of halides, as this has proven to be an effective strategy for achieving tunability in the material’s optical properties. This project would guide experimentalists and theorists toward which perovskites are most likely to be successfully synthesized and demonstrates an approach to descriptor identification that can be extended to arbitrary applications beyond perovskite stability predictions.

For this project, __it is required knowledge or interest__ in learning how to use computational tools and data analysis softwares such as Python or Mathematica.