Kim Taehee, Jeong Seongsik, Kim Kyeong-Hwan, Shim Hyunseok, Kim Dongho, Kim Hae-Jin
Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea.
School of Mechanical and Aerospace Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea.
ACS Appl Mater Interfaces. 2022 Jun 8;14(22):26004-26013. doi: 10.1021/acsami.2c03089. Epub 2022 May 23.
As attractive photoactive materials, metal halide perovskites demonstrate outstanding performance in a wide range of optoelectronic applications. Among the various compositions studied, mixed-halide perovskites have a finely tunable band gap that renders them desirable for targeted applications. Despite their advantages, photoinduced halide segregation often deters the photoelectric stability of the materials. Herein, we adopt a strategy of post-treating the perovskite surface with an organic spacer to generate a two-dimensional (2D) perovskite passivating layer. Trap-assisted recombination pathways can be selectively modulated by passivating the surface halide defects that cause photoinduced halide segregation. Fluorescence lifetime imaging of flat and bent surfaces of perovskites reveals that the perovskite lattice tolerates mechanical strain via the neutralizing passivation of ionic halide defects. Upon bending, the photocurrent response of the flexible photodetector is maintained over 83% for 2D passivated perovskite and drops to 23% for pristine perovskite. A flexible photodetector array built with 2D passivated perovskite, in combination with a deep learning algorithm, demonstrates excellent accuracy in determining letters of the alphabet for both flat (>96%) and bent (>93%) states. The connection of chemically modified charge carrier dynamics and mechanical properties revealed in this study offers valuable guidance for developing next-generation optoelectronic applications.
作为有吸引力的光活性材料，金属卤化物钙钛矿在广泛的光电子应用中表现出卓越性能。在研究的各种成分中，混合卤化物钙钛矿具有可精细调节的带隙，这使其适用于特定应用。尽管它们具有优势，但光致卤化物偏析常常阻碍材料的光电稳定性。在此，我们采用一种用有机间隔物对钙钛矿表面进行后处理的策略，以生成二维（2D）钙钛矿钝化层。通过钝化导致光致卤化物偏析的表面卤化物缺陷，可以选择性地调节陷阱辅助复合途径。钙钛矿平面和弯曲表面的荧光寿命成像表明，钙钛矿晶格通过对离子卤化物缺陷的中和钝化来耐受机械应变。弯曲时，二维钝化钙钛矿的柔性光电探测器的光电流响应保持在83%以上，而原始钙钛矿则降至23%。用二维钝化钙钛矿构建的柔性光电探测器阵列，结合深度学习算法，在确定字母表字母时，对于平面（>96%）和弯曲（>93%）状态都表现出优异的准确性。本研究中揭示的化学修饰电荷载流子动力学与机械性能之间的联系，为开发下一代光电子应用提供了有价值的指导。
