Effective impurity dopants for the halide perovskites

The halide perovskites, such as cesium tin bromide and methylammonium lead iodide, are high-performing light emitters and absorbers. For these applications, greater control over electrical conductivity would be a great benefit. However, it has proven difficult to achieve high and controllable p-type carrier concentrations in some cases, and reliable n-type-doping strategies have not been developed. In this work, possible dopants are first evaluated in the halide perovskites using first-principles calculations based on a hybrid functional with spin-orbit coupling. This approach not only leads to accurate predictions for band structure and crystal structures [1], but also provides a better description of dopant properties. We assess whether dopant impurities (such as Ag, Na, and Cu for acceptors, and Bi, Sc, and Y for donors) can act as shallow dopants on the proper substitutional site, and whether other configurations of these impurities might lead to compensation of potential electrical conductivity. Among the p-type dopants considered, sodium and silver are identified as the most promising acceptors for achieving p-type conductivity, and optimum chemical potential conditions for these dopants are identified [2]. Turning to donor doping, we find that common n-type dopants such as Bi are deep [3]. We demonstrate the validity of our first-principles calculations by comparing with optical measurements of Bi-doped CsPbBr₃ crystals. Bi donors are found to give rise to characteristic near-infrared luminescence, in good agreement with theoretical predictions. While Bi is a deep donor in the halide perovskites, yttrium and scandium are identified as promising donor dopants that are capable of yielding n-type conductivity in a variety of halide perovskite systems [3].

[1] M. W. Swift and J. L. Lyons, Chem. Mater. 35, 9370 (2023).

[2] M. W. Swift and J. L. Lyons, J. Phys. Chem. 127, 12735 (2023).

[3] J. L. Lyons, Chem. Mater. 33, 6200 (2021).

This work was performed in collaboration with Michael W. Swift and Sarah Brittman.