The inferior hole injection efficiency in blue perovskite light-emitting diodes (PeLEDs), caused by the large hole injection barrier and low hole mobility of conventional hole transport layers (HTLs), remains a critical limitation to achieving higher external quantum efficiency (EQE) and device stability. To address this challenge, we propose a rational interfacial engineering strategy employing p-type molecular doping to optimize device performance. By incorporating 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ) as a dopant in the poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) HTL, we significantly enhance hole mobility from 3.96×10⁻⁶ to 1.13×10⁻⁴ cm²/(V·s) and adjust the highest occupied molecular orbital energy level from -5.40 to -5.56 eV, facilitating efficient hole carrier injection and transport. Additionally, perovskite films deposited on the doped HTL exhibit improved crystallinity and a reduced defect density from 3.47×10¹⁸ to 3.18×10¹⁷ cm⁻³. Owing to these synergistic improvements, the optimized blue PeLEDs achieve a maximum EQE of 4.57% with an emission peak at 484 nm, representing a 4.02-fold enhancement over the pristine device. This work highlights the effectiveness of molecular doping in tailoring interfacial properties and balancing charge transport for high-performance blue PeLEDs.
Covalent organic frameworks (COFs) with excellent porosity and pre-designable structure have emerged as ideal and promising organic scaffolds for broad applications such as in gas storage, heterogeneous catalysis and fluorescence sensing. Herein, a hydrazone-based COF was synthesized by the condensation of 2,5-bis(2-methoxyethoxy) terephthalohydrazide ( BMTH ) with 1,3,5-triformylbenzene ( TFB ) under solvothermal conditions. The resulting COF material ( TFB-BMTH ) exhibits high crystallinity, excellent porosity with a BET surface area of 632 m 2 g −1 and good thermal and chemical stability. The photoactive TFB-BMTH shows significant catalytic activity and recyclability in photocatalytic oxidative hydroxylation of arylboronic acid. The high photocatalytic performance of TFB-BMTH could be attributed to the effective light-harvesting platform with the efficient generation, migration and separation properties of photogenerated charge pairs in such a system. In addition, TFB-BMTH showed significant fluorescence quenching for the sensing of Cu 2+ . X-ray photoelectron spectroscopy and Fourier transform infrared techniques verified the interaction between Cu 2+ and functional units in TFB-BMTH . This work demonstrates the development of multifunctional COFs and makes important contributions to functional exploration in heterogeneous organic transformation and sensing applications.
All-inorganic perovskite quantum dot (PeQD) light-emitting diodes (QLEDs) are promising candidates for the next-generation flat-panel displays and semiconductor lighting technology. However, the stability issues severely limit their commercial applications. In this study, highly stable CsPbX3 (X = Cl, Br, I) PeQD films were prepared using InX3 (X = Cl, Br, I) and trioctylphosphine oxide (TOPO) as inorganic–organic hybrid ligands to passivate the surface defects of PeQDs. The obtained InX3-TOPO-CsPbX3 PeQDs not only have high photoluminance quantum yields (PL QYs) and very narrow emission (14–35 nm) but also possess long-term stability. This is mainly due to the synergistic effect of InX3 and TOPO inorganic–organic surface ligand passivation, which can effectively inhibit the halogen vacancy and reduce the surface defect of PeQDs. In addition, the chemical states of InBr3-TOPO-CsPbBr3 PeQDs were analyzed by XPS technology and it was found that InX3-TOPO synergistic surface passivation can effectively reduce the Pb═O bond in the crystal lattice. Moreover, full-colored perovskite QLEDs based on InX3-TOPO-CsPbX3 PeQDs were achieved by using ZnO/PBD as the double electron transport layer, NiO/TFB as the double hole transport material, and InX3-TOPO-CsPbX3 PeQDs as the light-emitting layer. The EQE (%) and luminance (cd m–2) of red, green, and blue QLEDs based on these InX3-TOPO-CsPbX3 PeQDs were 8.2% and 9080 cd m–2, 7.8% and 18,600 cd m–2, and 1.62% and 164 cd m–2, respectively. This cooperative effect based on the InX3-TOPO hybrid passivation strategy will open a way for the preparation of highly efficient, stable, and color-tunable perovskite QLEDs.
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