Optoelectronic properties improvement of double perovskites Cs 2 Sn(Pb)I 6 by the hydrothermal method

Abstract

Herein, we report on the synthesis of perovskite Cs 2 Sn(Pb)I 6 powder via a modified hydrothermal method, in which Pb 2+ ions are introduced to Cs 2 SnI 6 to optimize the semiconductor properties of double perovskite. Results indicate that the introduction of 2 at% Pb 2+ into the Cs 2 SnI 6 not only facilitates fine thermal stability, smoother surface with small grain size, expanding the scope of absorption. Thence the photovoltaic properties of Cs 2 SnI 6 are improved where obtained a higher photocurrent density (∼ 70 µA cm −2 ). Combined with changes in photoelectric properties, perhaps a small amount of Pb doping plays a role in reducing the formation energy and surface energy of the compounds. On the contrary, excessive Pb doping destroys the synthesis of Cs 2 SnI 6 and reduces the purity of the compound; thus, affecting its application. This study provides useful insights into the development of double perovskites with high stability and efficiency.