Manipulation of Charge Dynamics for Efficient and Bright Blue Perovskite Light‐Emitting Diodes with Chiral Ligands

Abstract

Perovskite light‐emitting diodes (PeLEDs) emerge as a promising class of optoelectronic devices for next‐generation displays and lighting technology. However, the performance of blue PeLEDs lags far behind that of their green and red counterparts, including the unachieved trade‐off between high efficiency and high luminance, severe efficiency roll‐off, and unsatisfactory power efficiency. Here, a multi‐functional chiral ligand of L‐phenylalanine methyl ester hydrochloride is strategically introduced into quasi‐2D perovskites, which can effectively passivate defects, modulate the phase distribution, improve photoluminescence quantum yield, guarantee high‐quality film morphology, and enhance charge transport. Furthermore, ladder‐like hole transport layers are established, boosting charge injection and balance. The resultant sky‐blue PeLEDs (the photoluminescence peak is 493 nm and the electroluminescence peak is 497 nm) exhibit an external quantum efficiency of 12.43% at 1000 cd m−2 and a record power efficiency of 18.42 lm W−1, rendering that the performance is among the best blue PeLEDs.

Top-Down Exfoliation Process Constructing 2D/3D Heterojunction toward Ultrapure Blue Perovskite Light-Emitting Diodes

“…8,14 Nonetheless, the introduction of excess insulating organic ligands inevitably poses obstacles to the charge injection and transfer in quasi-2D PeLEDs. 9,15 Besides, the precise stoichiometric ratio control in the precursor solution can hardly avoid the disordered phase distribution of layered perovskites. 16,17 As a result, the negative effects of low brightness and poor color purity are imposed in quasi-2D perovskites, which are detrimental for high-quality full-color displays.…”

“…Blue perovskite light-emitting diodes (PeLEDs) are essential for achieving high-definition displays with a wide color gamut. − Numerous studies demonstrate that the development of efficient blue PeLEDs necessitates rational strategies intended for overcoming the critical challenges associated with wide-bandgap emission and crystal defect passivation. − At the present stage, the vast majority of research efforts have been devoted to exploring quasi-two-dimensional (quasi-2D) perovskite films. − By leveraging large organic cationic ligands to cleave three-dimensional (3D) crystals, quasi-2D perovskites with a strong quantum confinement effect achieve blue-shifted emission and lower defect density. , Nonetheless, the introduction of excess insulating organic ligands inevitably poses obstacles to the charge injection and transfer in quasi-2D PeLEDs. , Besides, the precise stoichiometric ratio control in the precursor solution can hardly avoid the disordered phase distribution of layered perovskites. , As a result, the negative effects of low brightness and poor color purity are imposed in quasi-2D perovskites, which are detrimental for high-quality full-color displays. , This predicament provokes careful consideration of how to unlock the full potential of dimensional engineering for blue PeLEDs.…”

Phosphine oxide modulator-ameliorated hole injection for blue perovskite light-emitting diodes

“…Metal halide perovskites have attracted enormous attention owing to their unique optical properties, such as impressive broad colour gamut, high colour purity, and photoluminescence quantum yields (PLQYs). [1][2][3][4][5] These merits emphasize the potential applications of perovskite lightemitting diodes (PeLEDs) in next-generation display and illumination. [6][7][8][9][10][11][12] Despite the considerable advances in enhancing the external quantum efficiencies (EQEs) of green (30.84%), red (25.8%), and near-infrared (23.8%) PeLEDs, [13][14][15][16][17][18][19] the current highest EQE of blue PeLEDs (∼480 nm) is only 18.65%, 20 lagging far behind those of narrow bandgap PeLEDs and slowing the path to their application in full-colour displays.…”

Defect Passivation in Quasi-2D Perovskite Light-Emitting Diodes by an Ibuprofen Additive

“…It is well known that molecular passivation can effectively suppress vacancy defects through providing coordination or ionic bonding to neutralize charged vacancy defects. For instance, the functional groups (CO, , PO, ,, SO, –NH 2 , ) can passivate defects in the perovskite films competently. Choy demonstrates that the 4-(2-aminoethyl) benzoic acid (ABA) coupling mechanism can not only passivate defects but also improve energy transfer at the interface of the perovskite layer, reducing the energy loss of excitons via nonradiative recombination .…”