Periodic Reporting for period 1 - WLEP (White Light-Emitting Diodes Based on Organometal Halide Perovskites)
Periodo di rendicontazione: 2021-09-01 al 2023-08-31
This project aims to solve one of the most important issues in the perovskite LED field, namely the lack of high-performance white perovskite LEDs. To tackle this issue, we systematically investigated the impacts of the lattice strain on the stability and efficiency of perovskite LEDs. Through the cation tailing strategy, a minimum lattice strain in perovskite film was achieved, which consequently resulted in a high-efficiency perovskite LED with a significantly improved device lifetime (T70) to 151 h and a peak external quantum efficiency (EQE) of 18.2%. We also studied the limiting factors of photoluminescence quantum yields (PLQYs) in blue perovskite LEDs and proposed a two-step mechanism involving exciton dissociation and electron–phonon interaction to explain the thermal quenching behavior in blue perovskite films. Ultimately, we successfully fabricated the first white perovskite LED based on two-dimensional tin perovskites.
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.
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.
a)We systematically investigated the impacts of lattice strain on the stability of high-efficiency PeLEDs, providing an insightful understanding of the relationship between lattice strain in perovskite films and device performances, as well as useful guidelines for developing PeLEDs with both high efficiencies and long lifetimes.
b)We successfully enhanced PLQY in blue perovskite films and 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 suggest that enhancing the radiative recombination rate and reducing the electron–phonon interaction-induced nonradiative recombination rate are crucial to achieving high-PLQY blue perovskite films at room temperature or above, which provides an insightful understanding of the limiting factors of the PLQY of blue perovskite films and affords useful guidelines for the development of highly efficient blue PeLEDs.
c)We fabricated a series of perovskite LEDs based on two-dimensional tin perovskites with different compositions. The champion device based on PEA2SnBr4 perovskite showed weak but wide EL emissions. The CIE coordinates at the maximum luminance were (0.33 0.36) demonstrating a pure white emission. This is the first white LED device achieved by tin-based perovskites.
b)We successfully enhanced PLQY in blue perovskite films and 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 suggest that enhancing the radiative recombination rate and reducing the electron–phonon interaction-induced nonradiative recombination rate are crucial to achieving high-PLQY blue perovskite films at room temperature or above, which provides an insightful understanding of the limiting factors of the PLQY of blue perovskite films and affords useful guidelines for the development of highly efficient blue PeLEDs.
c)We fabricated a series of perovskite LEDs based on two-dimensional tin perovskites with different compositions. The champion device based on PEA2SnBr4 perovskite showed weak but wide EL emissions. The CIE coordinates at the maximum luminance were (0.33 0.36) demonstrating a pure white emission. This is the first white LED device achieved by tin-based perovskites.