Yu Bufan, Duan Xingxing, Xing Zhaohui, Liu Jiacheng, Pan Yutong, Wang Lei, Chen Jiangshan, Ma Dongge
Institute of Polymer Optoelectronic Materials and Devices, Guangdong Basic Research Center of Excellence for Energy & Information Polymer Materials, State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China.
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China.
ACS Appl Mater Interfaces. 2025 Aug 13;17(32):45927-45936. doi: 10.1021/acsami.5c12585. Epub 2025 Aug 4.
Quasi-2D perovskites are emerging as promising materials for light-emitting applications due to their pronounced quantum confinement effects. Blue perovskite light-emitting diodes (PeLEDs) remain fundamentally challenging yet critically demanded for display applications. Current strategies employing quasi-2D perovskites face inherent trade-offs: 1) increased spacer cation content enhances quantum confinement for blueshift but deteriorates charge transport through insulating organic layers; 2) multiphase quantum well formation broadens emission spectra (fwhm >25 nm), compromising color purity; 3) chloride incorporation for bandgap widening induces deep-level traps and accelerates halide segregation under operational voltage. Herein, we address these intertwined challenges through multifunctional additive engineering using phenylbiguanide (PBG). The conjugated molecular structure with dual -NH/═NH groups enables 3-fold functionality: First, strong Pb-PBG coordination effectively passivates uncoordinated halide vacancies, suppressing nonradiative recombination and achieving a high photoluminescence quantum yield (PLQY) of 76.6%. Second, hydrogen-bonding networks between PBG and [PbX] frameworks immobilize halide ions, inhibiting electric-field-driven Cl/Br phase segregation. Third, PBG modulates crystallization kinetics to produce a narrow quantum well distribution for narrow emission (fwhm = 21 nm) at 472 nm and efficient Förster resonance energy transfer. The synergistic effects yield pure-blue PeLEDs with an impressive EQE of 9.32% at 472 nm, with stable emission and a 10-fold enhancement of lifetime compared to the pristine device without PBG. This work offers a promising approach to the development of high-performance blue PeLEDs using quasi-2D perovskites.
准二维钙钛矿因其显著的量子限制效应，正成为发光应用领域中颇具潜力的材料。蓝色钙钛矿发光二极管（PeLEDs）对于显示应用而言，在根本上仍具有挑战性，但却是迫切需要的。目前采用准二维钙钛矿的策略面临着固有的权衡：1）间隔阳离子含量的增加增强了量子限制以实现蓝移，但却恶化了通过绝缘有机层的电荷传输；2）多相量子阱的形成拓宽了发射光谱（半高宽>25 nm），损害了颜色纯度；3）引入氯以拓宽带隙会诱导深能级陷阱，并在工作电压下加速卤化物的相分离。在此，我们通过使用苯基双胍（PBG）的多功能添加剂工程来应对这些相互交织的挑战。具有双-NH/═NH基团的共轭分子结构具有三重功能：第一，强大的Pb-PBG配位有效地钝化了未配位的卤化物空位，抑制了非辐射复合，并实现了76.6%的高光致发光量子产率（PLQY）。第二，PBG与[PbX]框架之间的氢键网络固定了卤离子，抑制了电场驱动的Cl/Br相分离。第三，PBG调节结晶动力学，以产生窄量子阱分布，从而在472 nm处实现窄发射（半高宽=21 nm）和高效的Förster共振能量转移。这些协同效应产生了纯蓝色PeLEDs，在472 nm处具有令人印象深刻的9.32%的外量子效率（EQE），发射稳定，与没有PBG的原始器件相比，寿命提高了10倍。这项工作为使用准二维钙钛矿开发高性能蓝色PeLEDs提供了一种很有前景的方法。
