Strain effects on the structural stability and defect properties of γ-CsPbI3

• Published in: Applied surface science Vol. 679; p. 161235
• Main Authors: Zhang, Jianen, Guan, Li, Chen, Zhijuan, Luo, Tao, Yin, Tao, Ren, Xiaojie, Shi, Weicai, Liu, Chunzhi, Chen, Xiaobo, Li, Xu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2025
• Subjects: First-principles method γ-CsPbI3 Strain Structure stability Defect; First-principles method γ-CsPbI3 Strain Structure stability Defect
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161235

Effect of biaxial strain on the energy of defect formation and v1 defect level. [Display omitted] •Effect of biaxial strain on γ-CsPbI3 was investigated by first-principles method.•Biaxial strain on γ-CsPbI3 (001) planes is favorable for preserving black phase.•Tensile strain increases the formation energies of VI, VPb, VCs and ICs.•Compressive strain increases the formation energies of IPb and CsPb.•Compressive strain suppresses VI migration and makes its defect level shallower. Black γ phase CsPbI3 exhibits better structure stability at room temperature, making it a compelling candidate for perovskite solar cells. However, the long-term stability remains a challenge due to lattice strain. Here, the lattice structure stability and defect properties of γ-CsPbI3 under biaxial strains on the different planes were investigated by first-principles method. The results show that the tensile strain effectively reduces the PbI6 octahedral tilt to maintain the structural stability and improves the defect formation energies of VI, VPb, VCs and ICs, while the compressive strain can increase the formation energies of IPb and CsPb, hinders the diffusion of VI along the octahedral path and makes the defect level of VI shallower. The biaxial strain on the (001) plane is favourable for decreasing the formation enthalpy difference and maintaining the shallow level of VI to preserve the black phase structure, whereas that on the (100) plane is more beneficial for modulating these properties. This work offers theoretical guidance for applying strain to influence structure stability and suppress defect formation in γ-CsPbI3. Furthermore, it proposes a strategy utilizing lattice strain to modulate the energy levels of defects, thereby facilitating their passivation and enhancing device performance of perovskite photovoltaics.