Multifunctional Crystal Regulation Enables Efficient and Stable Sky‐Blue Perovskite Light‐Emitting Diodes

Abstract

Perovskite light-emitting didoes (PeLEDs) have shown considerable potential in solution-processable display applications. However, the performance of blue PeLEDs in terms of efficiency and stability hinders their practicality on account of severe trap-mediated nonradiative recombination losses and halide phase segregation. To ameliorate these issues, mixed-halide sky-blue perovskite materials are strategically modulated through crystal defect passivation with a trifurcate isocyanate oligomer, which leads to the synergistical suppression of charge trap density and halide ion migration. The proposed approach enables the performance improvement for sky-blue PeLEDs, exhibiting a peak external quantum efficiency of 14.82% and spectrally stable emission at 487 nm. In addition, prolonged operational lifetime and enhanced capability of moisture resistance are achieved simultaneously, approaching a half-lifetime of ≈2900 s at an initial brightness of 178 cd m -2 .

Zwitterions Narrow Distribution of Perovskite Quantum Wells for Blue Light‐Emitting Diodes with Efficiency Exceeding 15%

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Since the first room temperature lead halide perovskite light-emitting diode (PeLED) reported in 2014, [5] green, red, and near-infrared PeLEDs have been developed rapidly, with external quantum efficiency (EQE) all over 20%. [6][7][8][9][10][11][12] However, the EQE of blue PeLEDs is still lagging behind, [13][14][15][16] which undoubtedly restricts their applications in full-color displays and white-light illuminations. [2,[17][18][19] Recently, quasi-2D perovskites have been considered as emerging candidates for efficient blue emission, with high exciton binding energy and efficient radiative recombination, thanks to the quantum confinement and dielectric confinement effects.

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Suppressed Energy Transfer Loss of Dion–Jacobson Perovskite Enabled by DMSO Vapor Treatment for Efficient Sky-Blue Light-Emitting Diodes

“…However, the light emission from the n = 2 phase is completely suppressed for the PeLEDs of D 90 and D 120 and meanwhile the EL peak is red-shifted to 489 nm (sky-blue light emission with CIE coordinates of (0.09, 0.30)) for D 90 and 494 nm (cyan light emission with CIE coordinates of (0.07, 0.38)) for D 120 . The external quantum efficiencies (EQEs) (and current efficiencies (CEs)) of D 90 and D 120 are largely increased to 13.7% (20.2 cd A –1 ) and 15.5% (28.8 cd A –1 ), respectively, from 2.9% (3.6 cd A –1 ) of R 40 , as shown in Figure b and Figure S7, representing the best efficiencies for sky-blue PeLEDs, as shown in Table S3. ,,, This is a result of the efficient energy transfer with the an eliminated energy transfer gap and significantly suppressed energy losses of undesired light emission and nonradiative recombination by the treatment of DMSO vapor. A total of 30 PeLEDs for D 90 and D 120 are prepared and measured (Figure S8), showing high average EQEs of 10.6% and 12.1%, respectively.…”

Phase rearrangement for minimal exciton loss in a quasi-2D perovskite toward efficient deep-blue LEDs via halide post-treatment

“…[9][10][11][12] However, the EQEs of blue colour PeLEDs remain at approximately 10% for the sky-blue emission (B490 nm) 13,14 and even lower at 5% for the deep-blue emission (B470 nm). 15,16 Recently, Lia et al 17 and Tang et al 18 adopted passivation techniques to fabricate sky-blue emissive PeLEDs with peak EQEs of 12.5% at 489 nm and 14.82% at 487 nm, respectively. Chen et al 19 developed ultrapure deep-blue emissive PeLEDs with a high EQE of up to 2.11% at 465 nm by incorporating a 2D/3D perovskite heterostructure as the emissive layer.…”