Simultaneous Suppression of p-Doping and Nonradiative Recombination via Barium Incorporation for Highly Efficient Tin Perovskites.

High p-type self-doping and fast nonradiative recombination severely limit the optoelectronic performance of tin perovskites. Employing first-principles calculations, we show that incorporating barium (Ba) into the prototypical tin perovskite CsSnI 3 could enable simultaneous suppression of p-doping and nonradiative recombination. Ba acts as an energetically favorable donor and raises the Fermi level. This not only decreases the background hole concentration but also inhibits the formation of I vacancies that are the dominant nonradiative recombination centers, giving rise to an improvement of more than 2 orders of magnitude in carrier lifetime. Moreover, as the facile migration of I ions is basically a process assisted by I vacancies, Ba incorporation also suppresses the diffusion of I ions, which is beneficial to the enhancement of stability. The present study provides a promising strategy for developing high-performance tin perovskites.