Qi Heng, Tong Yu, Zhang Xuewen, Wang Hao, Zhang Lu, Chen Yali, Wang Yibo, Shang Jingzhi, Wang Kun, Wang Hongqiang
State Key Laboratory of Solidification Processing, Center for Nano Energy Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China.
Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710129, P. R. China.
Adv Mater. 2024 Nov;36(46):e2409319. doi: 10.1002/adma.202409319. Epub 2024 Sep 20.
Blue perovskite light-emitting diodes (PeLEDs) have attracted enormous attention; however, their unsatisfactory device efficiency and spectral stability still remain great challenges. Unfavorable low-dimensional phase distribution and defects with deeper energy levels usually cause energy disorder, substantially limiting the device's performance. Here, an additive-interface optimization strategy is reported to tackle these issues, thus realizing efficient and spectrally stable blue PeLEDs. A new type of additive-formamidinium tetrafluorosuccinate (FATFSA) is introduced into the quasi-2D mixed halide perovskite accompanied by interface engineering, which effectively impedes the formation of undesired low-dimensional phases with various bandgaps throughout the entire film, thereby boosting energy transfer process for accelerating radiative recombination; this strategy also diminishes the halide vacancies especially chloride-related defects with deep energy level, thus reducing nonradiative energy loss for efficient radiative recombination. Benefitting from homogenized energy landscape throughout the entire perovskite emitting layer, PeLEDs with spectrally-stable blue emission (478 nm) and champion external quantum efficiency (EQE) of 21.9% are realized, which represents a record value among this type of PeLEDs in the pure blue region.
蓝色钙钛矿发光二极管（PeLEDs）已引起了极大关注；然而，其不尽人意的器件效率和光谱稳定性仍然是巨大挑战。不利的低维相分布和具有更深能级的缺陷通常会导致能量无序，从而严重限制器件性能。在此，报道了一种添加剂界面优化策略来解决这些问题，从而实现高效且光谱稳定的蓝色PeLEDs。一种新型添加剂——甲脒四氟琥珀酸盐（FATFSA）被引入到准二维混合卤化物钙钛矿中，并结合界面工程，这有效地阻碍了在整个薄膜中形成具有各种带隙的不期望的低维相，从而促进能量转移过程以加速辐射复合；该策略还减少了卤化物空位，特别是具有深能级的与氯相关的缺陷，从而减少非辐射能量损失以实现高效辐射复合。受益于整个钙钛矿发光层均匀的能量分布，实现了具有光谱稳定的蓝色发射（478 nm）且最佳外量子效率（EQE）为21.9%的PeLEDs，这在这类纯蓝色区域的PeLEDs中代表了一个创纪录的值。
