Zhengzhou University research team uses inserted dipole layer to achieve high-power blue perovskite quantum dot LED

Blue light-emitting diodes, as one of the three primary colors and excitation light sources, have important application requirements in fields such as full-color display, general lighting, and signal transmission. In recent years, metal halide perovskites have become powerful candidates for the new generation of low-cost blue LEDs due to their high photoluminescence quantum yield, high color purity, and simple solution processability. To achieve high-performance blue perovskite LEDs, researchers have proposed various strategies, including material optimization, interface engineering, and device structure design. So far, the external quantum efficiency of blue perovskite LEDs has reached 26.4%, but power efficiency - a key indicator for evaluating LED power consumption - is still unsatisfactory.

  Given the enormous global energy footprint of LED technology and the inherent higher energy consumption of blue perovskite due to its wider bandgap compared to red and green counterparts, improving the PE of blue perovskite LEDs is crucial for designing energy-efficient optoelectronic devices. The PE value is determined by the formula PE=(π× L)/(J × V), where L, J, and V represent brightness, current density, and driving voltage, respectively. Therefore, to achieve high PE, it is necessary to maximize brightness at a specific current density while reducing the driving voltage. Compared with LEDs based on perovskite polycrystalline films, LEDs based on quantum dots are expected to achieve higher PE because QD emitters themselves have strong carrier confinement characteristics, which can achieve luminous efficiency close to the theoretical limit. However, the electrical insulation properties of organic ligands in QDs can seriously hinder carrier transport and recombination, thereby increasing the driving voltage and resulting in relatively low PE of these devices.

  Song Jizhong, Yao Jisong, and others from Zhengzhou University were able to reduce the driving voltage of blue light perovskite QLEDs and enhance radiative recombination by inserting the ordered dipole structure of poly (1,1-difluoroethylene) into the QD luminescent layer. The polymer dipole formed by PVDF can guide electrons and holes into the central region of the luminescent layer for radiative recombination, which helps to reduce the driving voltage of the device. Meanwhile, the electron withdrawing effect of F atoms on PVDF can effectively passivate uncoordinated Pb ² ⁺, while the corresponding H atoms can interact with halide ions of perovskite QDs, which can effectively suppress non radiative recombination. As a result, a record breaking power efficiency of 43.9 lm W ⁻¹ was successfully achieved in blue perovskite QLEDs, with an impressive brightness of 5474 cd m ⁻ ². In addition, the optimized device exhibits stable emission spectra and significantly improved operational stability, confirming the enormous potential of the proposed blue perovskite QLEDs strategy in practical applications.