Theoretical Study on the Carrier Mobility and Optical Properties of CsPbI₃ by DFT

Abstract

The advantages of organic–inorganic hybrid halide perovskites and related materials, such as high absorption coefficient, appropriate band gap, excellent carrier mobility, and long carrier life, provide the possibility for the preparation of low-cost and high-efficiency solar cell materials. Among the inorganic materials, CsPbI 3 is paid more attention to by researchers as CsPbI 3 has incomparable advantages. In this paper, based on density functional theory (DFT), we first analyze the crystal structure, electronic properties, and work function of two common bulk structures of CsPbI 3 and their slices, and then, we study the carrier mobility, exciton binding energy, and light absorption coefficient. Considering that CsPbI 3 contains heavy elements, the spin–orbit coupling (SOC) effect was also considered in the calculation. The highest mobility is that electrons of the cubic structure reach 1399 cm 2 V –1 S –1 after considering the SOC effect, which is equal to that of traditional solar cells (such as Si-based, PbSe, and PbTe). The lowest exciton binding energy is 101 meV in the cubic bulk structure, which is beneficial to the separation of photogenerated carriers. In the visible region, the absorption coefficient of the cubic structure is the best among all structures, reaching 10 5 cm –1 . Through the study of mobility, exciton binding energy, and light absorption coefficient, it is found that the cubic bulk structure in all structures of CsPbI 3 has the best photoelectric performance. This paper can provide some guidance for the experimental preparation of CsPbI 3 as a potential high-efficiency solar cell material.

A comparative study of the mechanical stability, electronic, optical and photocatalytic properties of CsPbX3 (X = Cl, Br, I) by DFT calculations for optoelectronic applications

“…109) but very close to the experimental value (Table 1). 83,102,103,109 It should be noted that the theoretical band gap obtained using PBE-GGA is a little bit underestimated compared to the experimental value, which could be due to the error in GGA. [119][120][121][122][123] It can be seen that when Cl is partially replaced by Br and I atoms, the band gap decreases because of an increase in the atomic size.…”

“…From Table 1, it can be seen that aer several k-points tests the optimized lattice parameter a ¼ b ¼ c of CsPbCl 3 was 5.785 Å, which was elongated about 3.9% and 11.2% aer the replacement of halide Cl atom by Br and I atoms and the obtained values were in a great agreement with other theoretical and experimental values. 32,82,83,[102][103][104][105][106][107][108][109][110]123 From the cell parameters and volumes of CsPbX 3 (X¼ Cl, Br, I) results, a relation can be expressed as CsPbCl 3 < CsPbBr 3 < CsPbI 3 (Table 1) with volume increments of 12.4% and 37.8% for CsPbBr 3 and CsPbI 3, respectively.…”

Regulation of Photovoltaic Response in ZSO-Based Multiferroic BFCO/BFCNT Heterojunction Photoelectrodes via Magnetization and Polarization

“…When a magnetic field was applied perpendicular to the direction of illumination, the BFCO/BFCNT heterojunction absorption layer deforms slightly due to the magnetostriction, stretching along the direction of the magnetic field, leading to a longitudinal shrinkage in the direction of illumination, which distorts the lattice to some extent, although the deformation is reversible. This distortion will inevitably increase the carrier scattering probability, which will shorten the mean carrier free time (τ) and reduce the mean carrier free path (λ), ultimately leading to an improvement of the carrier mobility (μ) because , where , , and , thus boosting the performance of the multiferroic oxide photoelectrodes.…”

Strain Engineering for Tailored Carrier Transport and Thermoelectric Performance in Mixed Halide Perovskites CsPb(I1–xBrx)3

“…A denser 6 × 12 × 12 k -point mesh and the more accurate Heyd–Scuseria–Ernzerhof (HSE06) functional with a 25% exact Hartree–Fock exchange were used to determine the carrier transport properties. In addition, the spin–orbit coupling (SOC) effect is considered here because of the heavy Pb atom although it underestimates the band gap as reported . Therefore, the scissor-operator approach was applied to correct the HSE06 with SOC band gaps to the experiment values using the equation E g (ε) = E g * (ε) + U, where E g * (ε) is the band gap obtained by our DFT calculations, while U is the correction to fulfill the experimental gap value E g (ε).…”

“…In addition, the spin−orbit coupling (SOC) effect is considered here because of the heavy Pb atom although it underestimates the band gap as reported. 50 Therefore, the scissoroperator approach 51 was applied to correct the HSE06 with SOC band gaps to the experiment values using the equation E g (ε) = E g *(ε) + U, where E g *(ε) is the band gap obtained by our DFT calculations, while U is the correction to fulfill the experimental gap value E g (ε). The thermoelectric transport properties, including the relaxation time-normalized electric conductivity σ/τ and the Seebeck coefficient S, as well as the resulting power factors (PF = S 2 σ) were computed based on the Boltzmann transport theory using BoltzTraP2.…”