Structural, Optical, and Electronic Properties of Wide Bandgap Perovskites: Experimental and Theoretical Investigations

Abstract

Wide bandgap hybrid halide perovskites based on bromine and chlorine halide anions have emerged as potential candidates for various optoelectronic devices. However, these materials are relatively less explored than the iodine-based perovskites for microscopic details. We present experiment and first-principles calculations to understand the structural, optical, and electronic structure of wide bandgap CH3NH3Pb(Br1-xClx)3 (x = 0, 0.33, 0.66, and 1) 3D hybrid perovskite materials. We substituted Br(-) with Cl(-) to tune the bandgap from 2.4 eV (green emissive) to 3.2 eV (blue (UV) emissive) of these materials. We correlate our experimental results with first-principles theory and provide an insight into important parameters like lattice constants, electronic structure, excitonic binding energy (EX), dielectric constant, and reduced effective mass (μr) of charge carriers in these perovskite semiconductors. Electronic structure calculations reveal that electronic properties are mainly governed by Pb 6p and halide p orbitals. Our estimates of EX within a hydrogen model suggest that an increase in EX by increasing the Cl(-) (chlorine) concentration is mainly due to a decrease in the dielectric constant with x and almost constant value of μr close to the range of 0.07me.

Recent Advances in Metal Halide‐Based Perovskite Light‐Emitting Diodes

“…Perovskites consisting of MAPbCl 3 , MAPbBr 3 , and MAPbI 3 have band‐gab energies of 3.1, 2.3, and 1.6 eV, respectively . These values come from the energy difference between (Pb)6s(X)np valence band maximum (VBM) and (Pb)6p conduction band minimum (CBM) orbitals with X=Cl, Br, or I …”

“…[32,39,48] Thesev alues come from the energy difference between (Pb)6s(X)np valence band maximum (VBM) and (Pb)6p conduction band minimum (CBM)orbitals with X = Cl, Br, or I. [64,65] Theb andgap energy can be tuned from 1.6t o2 .3 eV by the changing the I/Br ratio [48,66] (Figure 3a)a nd also from 2.3 to 3.1 eV by controlling the Cl/Br ratio. [32,67] Overall, by changing the halide ratio,t he bandgap energy can be tuned from 3.1 (UV) to 1.6 eV (NIR).…”

Effect of mixed halide contents on structural, electronic, optical and elastic properties of CsSnI3−xBrx for solar cell applications: first-principles study

“…The calculated results revealed that the conduction band minima and valance band maxima are located at the R high symmetry points, hence evidenced for the direct band gap semiconductors. The calculated band gaps by both potentials (GGA and mBJ) are listed in the table 2, from where it can be seen that the band gaps calculated with mBJ have been improved as compared to other theoretical results reported in literature but lower than to experimental values which is due the limitations and under estimations of GGA [26,27]. Direct band gap can also be detected at other symmetry points (M, G and X).…”

Morphology‐Tailored Halide Perovskite Platelets and Wires: From Synthesis, Properties to Optoelectronic Devices

“…MAPbCl 3 , MAPbBr 3 , and MAPbI 3 have bandgap energies of 3.11, 2.3, and 1.55 eV, respectively . These bandgaps correspond to the energy difference between (Pb)6s(X)np valence band maximum (VBM) and (Pb)6p conduction band minimum (CBM) …”