[16p-C41-1~12] New direction of perovskite solar cells

5:45 PM - 6:00 PM JST(8:45 AM - 9:00 AM UTC)English Presentation

[16p-C41-10] Electronic and Optical Properties and Defect Investigation of MASnX₃ (X = Cl, Br, and I) Perovskite Structures as Solar Cell Absorber

〇Qing Wang¹, Aimi Hiratsuka², Satoshi Iikubo¹ (1.Kyushu Univ., 2.Kyushu Inst. of Tech)

Keywords:

Perovskite,DFT calculation,Charged defect

Organic-inorganic hybrid perovskite materials, such as MAPbI₃, have demonstrated exceptional potential as photovoltaic materials due to their high-power conversion efficiency, and solar cells based on MAPbI₃ have reached a power conversion efficiency (PCE) over 25%. Despite similarities in electronic properties between MASnI₃ and MAPbI₃, the photoelectric efficiency and stability of tin halide perovskites are limited by self-p-doping and tin oxidation. It is essential to investigate the microscopic origin of these phenomena to propose solutions and promote the use of lead-free perovskite solar cells. In this work, a detailed investigation of the electronic and optical properties and thermodynamic stability and trapping activity of native defects in MASnX₃ is carried out, which is achieved using density functional theory (DFT) calculations. The results of defect energy calculations based on first-principles indicate that Sn vacancies and X-site interstitial atoms are easily formed among several defects in MASnX₃. Among them, MASnCl₃ is found to be less likely to form Sn vacancies, and is considered to be more stable than MASnBr₃ and MASnI₃ due to the stability of its formation energy and its tolerance factor (0.95) being close to that of ideal perovskite. X-ray absorption near edge structure (XANES) theoretical calculations show a small discrepancy between the XANES spectrum with Sn vacancies and that of the defect-free structure, whereas with interstitial X-site atoms, there is a clear discrepancy with the XANES spectrum of the defect-free structure. This may be due to the fact that the crystal structure around the interstitial X-site atoms is distorted, while the change in crystal structure due to the Sn vacancies is minimal.