Researchers at China's Shanghai University, Jilin University, University of Science and Technology of China, Chinese Academy of Sciences, Korea's Pohang University of Science and Technology (POSTECH) and UK's University of Cambridge have reported efficient and color-stable perovskite LEDs (PeLEDs) across the entire pure-red region, with a peak external quantum efficiency reaching 28.7% at 638 nm, enabled by incorporating a double-end anchored ligand molecule into pure-iodine perovskites.
Light-emitting diodes (LEDs) based on metal halide perovskites (PeLEDs) with high color quality and facile solution processing are promising candidates for full-color and high-definition displays. However, the team explained that despite the great success achieved in green PeLEDs with lead bromide perovskites, it is still challenging to realize pure-red (620–650 nm) LEDs using iodine-based counterparts, as they are constrained by the low intrinsic bandgap.
The research team used a unique double-ended organic molecule coordination to “anchor” the perovskite surface to stabilize its octahedral structure, successfully overcoming the mutual constraints between the spectral adjustment and photoelectric properties of the perovskite film.
The LED device obtained by the research team has a continuously adjustable spectrum in the range of 620-650 nm for pure red light, and the LED device emits at 638 nm. The quantum efficiency (EQE) reached 28.7%, setting a new record for the luminous efficiency of red perovskite LEDs. With bias voltage as high as 8 V, the radiative recombination center of the device hardly separates, showing excellent spectral stability.
