Electronic and Optical Modulation of Metal-Doped Hybrid Organic–Inorganic Perovskites Crystals by Post-Treatment Control

Abstract

Recently, considerable interest in the fields of photovoltaics, light emission, and photodetection absorbers has centered on hybrid organic–inorganic perovskites (HOIPs). Here, we report a combined photoluminescence and high-resolution photoemission study to investigate the defect-site passivation of the B-site methylammonium lead bromide perovskites (B site = In3+, Sr2+, and Li+). A distinctive behavior of the optical response is revealed by means of temperature-dependent time-resolved photoluminescence (TR-PL) measurements. Upon mild argon treatment, the initial thermal quenching rate with respect to the radiative transition rate (Γ0/Γv) ratio and thermal quenching activation energy (ΔEq) of Sr-doped MAPbBr3 is reduced by an order of magnitude. The average charge carrier lifetime (τave) of Sr-doped MAPbBr3 after treatment is significantly improved from 36 to 77 ns, respectively. Moreover, the occupied state of metal-doped MAPbBr3 probed by ultraviolet photoemission spectroscopy (UPS) indicates tunable charge transfer based on rational chemical design. Supported by density functional theory, small band gap changes are observed across Sr-, In-, and Li-doped cases. This work improves our understanding of the photophysics of HOIPs with the possible future aim of improving the stability of emergent perovskite materials by post-treatment control.