a)We systematically investigate the impacts of the lattice strain on the stability and efficiency of perovskite LEDs. Through the cation tailing strategy, we demonstrated a strong correlation between the lattice strain and the stability of perovskite LEDs. Additionally, we observed an increase in lattice strain after a long-time stability test, indicating that the degradation of the local perovskite lattice structure could be one of the degradation mechanisms for the long-term operation of perovskite LEDs. This work has been published in Advanced Energy Materials, 2023, 13, 2202185.
b)High efficiency blue emission perovskite LEDs are essential for achieving high-performance white perovskite LEDs. We demonstrated considerably enhanced PLQY in the blue perovskite films by promoting the radiative recombination rate and reducing the nonradiative recombination rate. Moreover, we proposed a two-step mechanism consisting of exciton dissociation and electron–phonon interaction to elucidate the thermal quenching phenomenon in mixed halide blue perovskite films. Our results highlighted that it is important to enhance the radiative recombination rate and reduce the intrinsic nonradiative recombination rate for achieving high-PLQY blue perovskite films at room temperature or above. These findings have been published in Advanced Optical Materials, 2023, 11, 2202528.
c)We fabricated a series of perovskite LEDs based on two-dimensional tin perovskites with different compositions. The champion device showed weak but wide EL emissions. The CIE coordinates at the maximum luminance were (0.33 0.36) demonstrating a pure white emission. The device efficiency was quite low, and extensive optimization will be needed to further improve the device performance. However, it is the first white LED device achieved by tin perovskites.
