Efficient passivation of DY center in CH3NH3PbBr3 by chlorine: Quantum molecular dynamics

• Published in: Nano research Vol. 15; no. 3; pp. 2112 - 2122
• Main Authors: Shi, Ran, Fang, Wei-Hai, Vasenko, Andrey S., Long, Run, Prezhdo, Oleg V.
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.03.2022
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Bismuth; Carrier density; Charge density; Chemistry and Materials Science; Chlorine; Condensed Matter Physics; Coupling (molecular); Crystal lattices; Current carriers; Density functional theory; Design defects; Doping; Efficiency; Electrical resistivity; Electromagnetic absorption; Hole traps; Holes (electron deficiencies); Materials Science; Metal halides; Molecular dynamics; Morphology; Nanotechnology; Optoelectronic devices; Passivity; Perovskites; Photovoltaic cells; Recombination; Research Article; Simulation; Solar cells; Toxicity; Valence band; Hybrid organic-inorganic perovskite; charge trapping and recombination; DY; time-domain density functional theory; nonadiabatic molecular dynamics; center and Cl passivation
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-021-3840-y

MAPbBr 3 (MA = CH 3 NH 3 + ) doping with bismuth increases electric conductivity, charge carrier density and photostability, reduces toxicity, and expands light absorption. However, Bi doping shortens excited-state lifetimes due to formation of DY − charge recombination centers. Using nonadiabatic molecular dynamics and time-domain density functional theory, we demonstrate that the DY − center forms a deep, highly localized hole trap, which accelerates nonradiative relaxation ten-fold and is responsible for 90% of carrier losses. Hole trapping occurs by coupling between the valence band and the trap state, facilitated by the Br atoms surrounding the Bi dopant. Passivation of the DY − center with chlorines heals the local geometry distortion, eliminates the trap state, and makes the carrier lifetimes longer than even in pristine MAPbBr 3 . The decreased charge recombination arises from reduced nonadiabatic coupling and shortened coherence time, due to diminished electron-hole overlap around the passivated defect. Our study demonstrates accelerated nonradiative recombination in Bi-doped MAPbBr 3 , suggests a strategy for defect passivation and reduction of nonradiative energy losses, and provides atomistic insights into unusual defect properties of metal halide perovskites needed for rational design of high-performance perovskite solar cells and optoelectronic devices.