Ma Dongxin, Todorović Petar, Meshkat Shadi, Saidaminov Makhsud I, Wang Ya-Kun, Chen Bin, Li Peicheng, Scheffel Benjamin, Quintero-Bermudez Rafael, Fan James Z, Dong Yitong, Sun Bin, Xu Chao, Zhou Chun, Hou Yi, Li Xiyan, Kang Yuetong, Voznyy Oleksandr, Lu Zheng-Hong, Ban Dayan, Sargent Edward H
Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, Ontario M1C 1A4, Canada.
J Am Chem Soc. 2020 Mar 18;142(11):5126-5134. doi: 10.1021/jacs.9b12323. Epub 2020 Mar 9.
Metal halide perovskites show promise for light-emitting diodes (LEDs) owing to their facile manufacture and excellent optoelectronic performance, including high color purity and spectral stability, especially in the green region. However, for blue perovskite LEDs, the emission spectrum line width is broadened to over 25 nm by the coexistence of multiple reduced-dimensional perovskite domains, and the spectral stability is poor, with an undesirable shift (over 7 nm) toward longer wavelengths under operating conditions, degradation that occurs due to phase separation when mixed halides are employed. Here we demonstrate chloride insertion-immobilization, a strategy that enables blue perovskite LEDs, the first to exhibit narrowband (line width of 18 nm) and spectrally stable (no wavelength shift) performance. We prepare bromide-based perovskites and then employ organic chlorides for dynamic treatment, inserting and immobilizing chlorides to blue-shift and stabilize the emission. We achieve sky-blue LEDs with a record luminance over 5100 cd/m at 489 nm, and an operating half-life of 51 min at 1500 cd/m. By device structure optimization, we further realize an improved EQE of 5.2% at 479 nm and an operating half-life of 90 min at 100 cd/m.
金属卤化物钙钛矿因其易于制造和出色的光电性能，包括高色纯度和光谱稳定性，在发光二极管（LED）领域展现出了潜力，尤其是在绿色区域。然而，对于蓝色钙钛矿LED，由于多种低维钙钛矿域的共存，发射光谱线宽拓宽至超过25纳米，且光谱稳定性较差，在工作条件下会向更长波长出现不期望的偏移（超过7纳米），这种降解是在使用混合卤化物时由于相分离而发生的。在此，我们展示了氯离子插入固定法，这是一种能实现蓝色钙钛矿LED的策略，首次展现出窄带（线宽为18纳米）和光谱稳定（无波长偏移）的性能。我们制备基于溴化物的钙钛矿，然后使用有机氯化物进行动态处理，插入并固定氯离子以使发射蓝移并稳定下来。我们实现了在489纳米处记录亮度超过5100 cd/m²的天蓝色LED，以及在1500 cd/m²下51分钟的工作半衰期。通过器件结构优化，我们进一步在479纳米处实现了5.2%的改进外量子效率（EQE）以及在100 cd/m²下90分钟的工作半衰期。
