Effects of Bromine Doping on the Structural Properties and Band Gap of CH₃NH₃Pb(I_1–xBr_x)₃ Perovskite

Abstract

An experimental and theoretical study is reported to investigate the influence of bromine doping on CH 3 NH 3 Pb(I 1– x Br x ) 3 perovskite for Br compositions ranging from x = 0 to x = 0.1, in which the material remains in the tetragonal phase. The experimental band gap is deduced from UV–vis absorption spectroscopy and displays a linear behavior as a function of bromine concentration. Density functional theory calculations are performed for five different series of randomly doped structures in order to simulate the disorder in bromine doping sites. The computations predict a linear variation of the lattice parameters, supercell volume, density, band gap, and formation energy in the considered doping range. The calculated evolution of the band gap as the function of Br doping is in excellent agreement with the experimental data, provided that different Br doping configurations are included in the simulations. The analysis of the structural and electronic properties shows a correlation between the increase of the band gap and the increased distortion of the Pb(I 1– x Br x ) 6 octahedrons. Additionally, the simulations suggest that in CH 3 NH 3 Pb(I 1– x Br x ) 3 bromine doping is likely to occur at both the equatorial and apical positions of the octahedrons.

Cetrimonium bromide and potassium thiocyanate assisted post-vapor treatment approach to enhance power conversion efficiency and stability of FAPbI3 perovskite solar cells

“…It could be due to the slight diffusion of bromine ions (Br − ) and or thiocyanate ions (SCN − ). 21,22 Steady-state photoluminescence (PL) curves of different FAPbI 3 layers have been shown in Fig. 3(c).…”

Understanding the Semi-Switchable Thermochromic Behavior of Mixed Halide Hybrid Perovskite Nanorods

“…At room temperature, MAPbI 3 has a tetragonal phase, whereas MAPbBr 3 has a cubic phase. Consequently, MAPb­(I 1– x Br x ) 3 is known to undergo a phase transition from the tetragonal phase to the cubic phase for bromine doping >20% . A part of MAPbIBr 2 will be corroded by moisture and high temperature, and the final products of the degradation process contain PbI 2 and PbBr 2 .…”

Luminescence and Structural Characteristics of Lead Halide Perovskite Films Deposited In Situ by a Versatile Multisource Aerosol Assisted Chemical Vapor Deposition (AACVD) Method

“…The gap widening is consistent with the blueshift in the excitation spectra, is associated with an increased Cl − content, [ 46 ] and is close to the value expected for the MAPbBr 2 Cl (2.53 eV). [ 47 ] The bandgap versus R MA‐Pb was fitted with a linear function ( R 2 = 0.99419), and this correlation has been observed for both, lead‐based and lead‐free perovskites in which the ratio between two halogen species were carefully tuned, [ 48–50 ] suggesting a high chemical composition control in the AACVD‐synthesized films.…”