Gao Weiqi, Liu Songlong, Chen Yang, Niu Kaixin, Lu Zheyi, Li Zhiwei, Zeng Zhiyao, Xiao Yulong, Zhai Yaxin, Liu Yuan, Wang Yiliu
Key Laboratory for Micro-Nano Optoelectronic Devices of Ministry of Education, School of Physics and Electronics, Hunan University, Changsha, 410082, China.
Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics, Hunan Normal University, Changsha, 410081, China.
Small. 2024 Aug;20(35):e2402159. doi: 10.1002/smll.202402159. Epub 2024 Apr 28.
The fabrication of perovskite single crystal-based optoelectronics with improved performance is largely hindered by limited processing techniques. Particularly, the local halide composition manipulation, which dominates the bandgap and thus the formation of heterostructures and emission of multiple-wavelength light, is realized via prevalent liquid- or gas-phase anion exchange with the utilization of lithography, while the monocrystalline nature is sacrificed due to polycrystalline transition in exchange with massive defects emerging, impeding carrier separation and transportation. Thus, a damage-free and lithography-free solid-state anion exchange strategy, aiming at in situ halide manipulation in perovskite monocrystalline film, is developed. Typically, CsPbCl working as medium to deliver halide is van der Waals (vdW) assembled to specific spots of CsPbBr followed by the removal of CsPbCl after anion exchange, with the halide composition in contact area modulated and monocrystalline nature of CsPbBr preserved. CsPbBr-CsPbBrCl monocrystalline heterostructure has been achieved without lithography. Device based on the heterostructure shows apparent rectification behavior and improved photo-response rate. Heterostructure arrays can also be constructed with customized medium crystal. Furthermore, the halide composition can be accurately tuned to enable full coverage of visible spectra. The solid-state exchange enriches the toolbox for processing vulnerable perovskite and paves the way for the integration of monocrystalline perovskite optoelectronics.
有限的加工技术在很大程度上阻碍了高性能钙钛矿单晶基光电器件的制造。特别是，局部卤化物成分的调控主导着带隙，进而影响异质结构的形成和多波长光的发射，这是通过利用光刻技术进行普遍的液相或气相阴离子交换来实现的，然而，由于在交换过程中出现大量缺陷导致多晶转变，单晶性质被牺牲，从而阻碍了载流子的分离和传输。因此，开发了一种无损且无需光刻的固态阴离子交换策略，旨在对钙钛矿单晶薄膜进行原位卤化物调控。具体而言，用作卤化物传递介质的CsPbCl通过范德华（vdW）组装到CsPbBr的特定位置，然后在阴离子交换后去除CsPbCl，从而调节接触区域的卤化物成分并保留CsPbBr的单晶性质。无需光刻即可实现CsPbBr-CsPbBrCl单晶异质结构。基于该异质结构的器件表现出明显的整流行为和提高的光响应速率。异质结构阵列也可以用定制的介质晶体构建。此外，可以精确调节卤化物成分以实现对可见光谱的全覆盖。固态交换丰富了处理易损钙钛矿的工具库，并为单晶钙钛矿光电器件的集成铺平了道路。
