Highly enhanced Quantum dot light-emitting diode performance by controlling energy resonance in inorganic insertion layers

Quantum-dot light-emitting diodes (QLED) have become a research trend in the field of new displays due to their low cost, wide color gamut, narrow bandwidth, and characteristics that enable production through the solution-gel method. However, the electrical performance of QLED is consistently constrained by energy losses and imbalanced charge carrier injection. This motivates our focus on exciton recombination and energy losses within the quantum-dot layer to enhance the electrical efficiency of QLED. In this work, we introduce a method using a CdZnS quantum dot (B-QD) interlayer to modulate energy transfer and charge carrier transport in QLED devices employing CdSe quantum dot (G-QD) as the emissive layer. By strategically incorporating a B-QD layer between the G-QD and HTL/ETL, we facilitate energy transfer due to the overlap between the excitation wavelength of B-QD and the absorption wavelength of G-QDs. This leads to enhanced energy injection in QLED devices, resulting in a high current efficiency of 39.54 Cd/A and a peak brightness of 522,272 cd/m2 for efficient QLED. The corresponding external quantum efficiency (EQE) is greatly improved from 5.62 % to 9.4 %. Our work provides a straightforward and effective approach to modulate exciton recombination and energy injection and further can be applicable to other photo-electronics devices.