Cs2TiI6 (Cs2TiIxBr6-x) Halide Perovskite Solar Cell and Its Point Defect Analysis

Abstract

This work presents a comprehensive numerical study for designing a lead-free, all-inorganic, and high-performance solar cell based on Cs2TiI6 halide perovskite with all-inorganic carrier transport layers. A rigorous ab initio density-functional theory (DFT) calculation is performed to identify the electronic and optical properties of Cs2TiI6 and, upon extraction of the existing experimental data of the material, the cell is designed and optimized to the degree of practical feasibility. Consequently, a theoretical power conversion efficiency (PCE) of 21.17% is reported with inorganic TiO2 and CuI as carrier transport layers. The calculated absorption coefficient of Cs2TiI6 reveals its enormous potential as an alternative low-bandgap material for different solar cell applications. Furthermore, the role of different point defects and the corresponding defect densities on cell performance are investigated. It is found that the possible point defects in Cs2TiI6 can form both the shallow and deep defect states, with deep defect states having a prominent effect on cell performance. For both defect states, the cell performance deteriorates significantly as the defect density increases, which signifies the importance of high-quality material processing for the success of Cs2TiI6-based perovskite solar cell technology.

Improving the Efficiency and Stability of Perovskite Solar Cells by Refining the Perovskite-Electron Transport Layer Interface and Shielding the Absorber from UV Effects

“…The EVBM, ECBM, and band gap data for PVK were obtained from our previous works 33 and FTO. 56 The energy band alignment diagram presented in this study illustrates a significant improvement in the performance of PSCs through the incorporation of an SSSO as both a passivating layer at the interface and a UV filter. The conduction band energy level (ECB) in the FTO/SnO 2 −SSSO film aligns more compatibly with the energy level of the PVK layer compared to the ECB in the pure FTO/SnO 2 film.…”

“…In Figure f, we displayed an energy band alignment diagram for the devices being studied. The EVBM, ECBM, and band gap data for PVK were obtained from our previous works and FTO . The energy band alignment diagram presented in this study illustrates a significant improvement in the performance of PSCs through the incorporation of an SSSO as both a passivating layer at the interface and a UV filter.…”

Phase Separation of Br-Doped CsPbI3: A Combined Cluster Expansion, Monte Carlo, and DFT Study

“…The band structure and optical absorption results demonstrated that all A 2 Sn 1−x Ti x Br 6 (A = K, Rb, Cs) materials are semiconductors with band gaps between 0.9-1.6 eV, and A 2 TiBr 6 (A = K, Rb, Cs) compounds have the highest optical absorption both in the visible and ultraviolet regions, making them excellent materials for photovoltaic applications. Urmi et al computed the opto-electronic properties of Cs 2 TiI 6 (Cs 2 TiI x Br 6-x ) halide perovskite and the findings showed that this material has a considerable potential as a low-band gap alternative material for photovoltaic applications [28]. In this work, the cluster expansion (CE) method based on a genetic algorithm was used to predict new structures of Br-doped CsPbI 3 and to further predict their structural, electronic, optical, mechanical, and thermodynamic properties using the first-principle calculations.…”