Sources of nonradiative recombination in halide perovskites

While halide perovskites exhibit great promise in highly efficient solar cells and light emitters, their bottleneck of nonradiative losses has become increasingly apparent. To further enhance their optoelectronic performance, identifying the sources of nonradiative recombination is key. Despite the fact that nonradiative recombination rates can be experimentally measured, it is challenging to determine the microscopic nature of the nonradiative sources. In recent years, we have developed first-principles approaches that allow us to quantitatively compute the defect-assisted nonradiative recombination [1] and Auger recombination [2] rates, and to rigorously identify the nature of the nonradiative losses. By applying our methodology to halide perovskites, we have identified a number of important defects that mediate nonradiative recombination, including intrinsic defects such as iodine interstitials [3,4] and hydrogen vacancies [5], and extrinsic defects such as bismuth impurities [6]. We show that the commonly used methylammonium cation does not suppress nonradiative recombination, but in fact gives rise to the formation of hydrogen vacancies. We have also demonstrated the origin of the unexpectedly strong Auger recombination in halide perovskites [7,8]. These important insights will guide further optimization of perovskite solar cells toward enhanced performance. 

This work was performed in collaboration with Mark E. Turiansky, Jimmy-Xuan Shen, and Chris G. Van de Walle.

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[3] X. Zhang et al., Phys. Rev. B 101, 140101 (2020). 

[4] X. Zhang et al., Cell Rep. Phys. Sci. 2, 100604 (2021).

[5] X. Zhang et al., Nat. Mater. 20, 971 (2021).

[6] X. Zhang et al., J. Mater. Chem. A 8, 12964 (2020).

[7] J.-X. Shen et al., Adv. Energy Mater. 8, 1801027 (2018).

[8] X. Zhang et al., Adv. Energy Mater. 10, 1902830 (2020).