First Principles Calculation and Experimental Verification of the Effect of Li+ Doping on Photoelectric Properties of Double Perovskite Cs2sni6

Abstract

Double perovskite Cs 2 SnI 6 and its doping products (with SnI 2 , SnF 2 or organic lithium salts added) have been utilized as p–type hole transport materials for perovskite and dye–sensitized solar cells in many researches, where the mechanism for producing p–type semiconductor is rarely reported. In this paper, the mechanism of p–type semiconductor generated by Li + doped Cs 2 SnI 6 was revealed by first–principles simulation. Li + entered Cs 2 SnI 6 lattice by interstitial doping to form strong correlated Li–I bonds, resulting in the splitting of the α spin orbital of I–p at the top of valence band, with the intermediate energy levels created and the absorption edge redshifted. The experimental results confirmed that Li + doping neither changed the crystal phase of Cs 2 SnI 6 , nor introduced impurities. The Hall effect test results showed that Li + doping transformed Cs 2 SnI 6 into p–type semiconductor, and substantially promoted its carrier mobility (356.6 cm 2 /Vs), making it an ideal hole transport material.

Keywords: First principles calculation, Perovskite, Hole transport, Doping, Ultrasonic spraying