Ye Yong-Chun, Li Yanqing, Tian Yu, Cai Xiao-Yi, Shen Yang, Shen Kong-Chao, Gao Xingyu, Song Fei, Wang Wenjun, Tang Jian-Xin
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, China.
Nanoscale. 2021 Jan 7;13(1):340-348. doi: 10.1039/d0nr07677e. Epub 2020 Dec 21.
Organic-inorganic hybrid lead halide perovskites are potential candidates for next-generation light-emitting diodes (LEDs) in terms of tunable emission wavelengths, high electroluminescence efficiency, and excellent color purity. However, the device performance is still limited by severe non-radiative recombination losses and operational instability due to a high degree of defect states on the perovskite surface. Here, an effective surface engineering method is developed via the assistance of guanidinium iodide (GAI), which allows the formation of surface-2D heterophased perovskite nanograins and surface defect passivation due to the bonding with undercoordinated halide ions. Efficient and stable red-emission LEDs are realized with the improved optoelectronic properties of GAI-modified perovskite nanograins by suppressing the trap-mediated non-radiative recombination loss. The champion device with a high color purity at 692 nm achieves an external quantum efficiency of 17.1%, which is 2.3 times that of the control device. Furthermore, the operational stability is highly improved, showing a half-lifetime of 563 min at an initial luminance of 1000 cd m. The proposed GAI-assisted surface engineering is a promising approach for defect passivation and phase engineering in perovskite films to achieve high-performance perovskite LEDs.
有机-无机杂化铅卤化物钙钛矿因其可调谐发射波长、高电致发光效率和出色的色纯度，是下一代发光二极管（LED）的潜在候选材料。然而，由于钙钛矿表面存在高度的缺陷态，器件性能仍受到严重的非辐射复合损耗和运行不稳定性的限制。在此，通过碘化胍（GAI）的辅助开发了一种有效的表面工程方法，该方法由于与低配位卤离子的键合作用，可形成表面二维异相钙钛矿纳米颗粒并实现表面缺陷钝化。通过抑制陷阱介导的非辐射复合损耗，利用GAI修饰的钙钛矿纳米颗粒改善的光电性能实现了高效稳定的红色发光LED。在692 nm处具有高色纯度的冠军器件实现了17.1%的外量子效率，是对照器件的2.3倍。此外，运行稳定性得到了极大提高，在初始亮度为1000 cd m时半寿命为563分钟。所提出的GAI辅助表面工程是一种用于钙钛矿薄膜中缺陷钝化和相工程以实现高性能钙钛矿LED的有前途的方法。
