Liu Dongtao, Bi Jinxin, Xu Weidong, Orr Kieran W P, Wang Fei, Liu Xueping, Ren Aobo, Zhang Jing, Hinder Steven, Li Bowei, Luo Xiaoguang, Shen Yonglong, Hu Hanlin, Shao Guosheng, Stranks Samuel D, Su Lei, Zhang Wei
Advanced Technology Institute, University of Surrey, Guildford GU2 7XH, UK.
School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK.
Sci Adv. 2025 Jun 27;11(26):eadu3459. doi: 10.1126/sciadv.adu3459.
Applying mechanical strain and strain engineering to halide perovskites has endowed them with intriguing properties. However, an in-depth understanding of mechanical strain, including residual strain in halide perovskites, remains incomplete, coupled with the critical challenge of decoupling strain effects from other interferences. Here, we examine the relaxation of residual tensile strain in three-dimensional (3D) halide perovskites through 2D/3D perovskite heterojunction formation. The 2D perovskite induces structural fragmentation in 3D perovskites, facilitating plastic relaxation of tensile strain. By isolating extrinsic crystalline phase interference and exciton-related optical disturbances, we observe that 3D perovskites retain high crystallinity only with moderate tensile strain relaxation. This moderate relaxation enhances optoelectronic properties in 3D perovskites, including broadened band-to-band absorption and prolonged charge carrier lifetime, markedly contributing to an increase in the maximum attainable power conversion efficiency in photovoltaic devices. Our findings outline conditions for strain relaxation that optimize optoelectronic properties, advancing strain engineering in halide perovskites.
将机械应变和应变工程应用于卤化物钙钛矿赋予了它们引人入胜的特性。然而，对机械应变的深入理解，包括卤化物钙钛矿中的残余应变，仍然不完整，同时还面临着将应变效应与其他干扰因素解耦的严峻挑战。在此，我们通过二维/三维钙钛矿异质结的形成来研究三维卤化物钙钛矿中残余拉伸应变的弛豫。二维钙钛矿在三维钙钛矿中诱导结构破碎，促进拉伸应变的塑性弛豫。通过隔离外在晶相干扰和激子相关的光学干扰，我们观察到三维钙钛矿仅在适度的拉伸应变弛豫下保持高结晶度。这种适度的弛豫增强了三维钙钛矿中的光电特性，包括拓宽的带间吸收和延长的电荷载流子寿命，显著有助于提高光伏器件中可达到的最大功率转换效率。我们的研究结果概述了优化光电特性的应变弛豫条件，推动了卤化物钙钛矿中的应变工程发展。
