Researchers from Sweden's Linköping University, China's Hong Kong Polytechnic University, Northwestern Polytechnical University, Hunan University and Jilin University have demonstrated bright perovskite light-emitting diodes (PeLEDs) with a peak radiance of 2409 W sr−1 m−2 and negligible current-efficiency roll-off, maintaining high external quantum efficiency over 20% even at current densities as high as 2270 mA cm−2.
Device configuration and cross-sectional SEM image of the PeLED. Image from: Nature Communications
One of the key advantages of perovskite light-emitting diodes (PeLEDs) is their potential to achieve high performance at much higher current densities compared to conventional solution-processed emitters. However, state-of-the-art PeLEDs have not yet reached this potential, often suffering from severe current-efficiency roll-off under intensive electrical excitations. The team's new work hopes to help tackle this obstacle.
This significant improvement shown by the scientists was achieved through the incorporation of electron-withdrawing trifluoroacetate anions into three-dimensional perovskite emitters, resulting in retarded Auger recombination due to a decoupled electron-hole wavefunction.
Trifluoroacetate anions can additionally alter the crystallization dynamics and inhibit halide migration, facilitating charge injection balance and improving the tolerance of perovskites under high voltages. Our findings shed light on a promising future for perovskite emitters in high-power light-emitting applications, including laser diodes.
In this study, the team achieved bright and stable perovskite light-emitting diodes, overcoming significant limitations of current-efficiency roll-off at high current densities. Moreover, the scientists demonstrated that dense and smooth perovskite films are crucial for balancing charge injection at high electrical excitation and thus high brightness. Further studies reveal that the use of TFA− anions in perovskites suppresses halide migration and hence contribute to decent device stability.
The team's demonstration of high-performance PeLEDs under intense electrical excitation could open possibilities for their use in high-power applications including the development of perovskite laser diodes.
