Photoluminescence Enhancement for Efficient Mixed‐Halide Blue Perovskite Light‐Emitting Diodes

Abstract

The development of highly efficient blue perovskite light‐emitting diodes (PeLEDs) remains a big challenge, requiring more fundamental investigations. In this work, significant photoluminescence enhancement in mixed halide blue perovskite films is demonstrated by using a molecule, benzylphosphonic acid, which eventually doubles the external quantum efficiency to 6.3% in sky‐blue PeLEDs. The photoluminescence enhancement is achieved by forming an oxide‐bonded perovskite surface at grain boundaries and suppressing electron–phonon interaction, which enhances the radiative recombination rate and reduces the nonradiative recombination rate, respectively. Moreover, severe thermal quenching is observed in the blue perovskite films, which can be explained by a two‐step mechanism involving exciton dissociation and electron–phonon interaction. The results suggest that enhancing the radiative recombination rate and reducing the electron–phonon interaction‐induced nonradiative recombination rate are crucial for achieving blue perovskite films with strong emission at or above room temperature.

Stable and Efficient Mixed‐halide Perovskite LEDs

“…[84] Ion migration is accelerated at the grain boundaries rather than inside of the grains owing to the higher ion diffusion and accumulation at the grain boundaries. [85] Therefore, defect and grain boundary passivation are essential for reducing ion migration and ultimately preventing halide segregation in MHPs.…”

Phosphonic Chloride Assisted Fabrication of Highly Emissive Mixed Halide Perovskite Films in Ambient Air for Blue Light-Emitting Diodes

“…12−14 Regardless of the differences in these two strategies, a common requirement remains in enhancing the emission of the perovskite films, which is considered as one of the most important factors for improving the performance of blue PeLEDs. 2,15,16 In addition to the device performance, the fabrication cost is another critical concern for the applications of PeLEDs. 17 So far, most of the PeLEDs are fabricated in a glovebox filled with an inert gas to prevent water invasion.…”

“…Metal halide perovskites have attracted extensive interest for light-emitting applications in recent years, and huge progress has been achieved in perovskite light-emitting diodes (PeLEDs). − Blue PeLEDs are drawing particular attention in recent years, and their performance has increased rapidly . Two typical strategies are generally used to produce blue perovskite films and LEDs, i.e., quantum confinement and mixed halide strategy. , The first one relies on the significant decrease in the size or dimensionality of perovskite crystals to induce a strong quantum confinement effect, , and the second one is realized by incorporating Cl in Br-based perovskite to increase the bandgap energy. − Regardless of the differences in these two strategies, a common requirement remains in enhancing the emission of the perovskite films, which is considered as one of the most important factors for improving the performance of blue PeLEDs. ,, …”

Surface co-modification enabling efficient and spectrally stable mixed-halide blue light-emitting diodes

“…[3][4][5] However, the color-stable and efficient blue PeLEDs are still far behind, especially for the blue emission with a wavelength less than 480 nm, which greatly limits their commercialization. [6][7][8][9][10] Generally, blue emission can be achieved by modulating the quasi-two-dimensional (quasi-2D) quantum well distribution, enhancing the quantum confinement effect of CsPbBr 3 , or doping Cl species to change the degree of orbital overlap, respectively. [11][12][13][14][15][16][17][18][19][20] In recent years, there has been a significant focus on developing blue PeLEDs based on the first two techniques.…”

“…3–5 However, the color-stable and efficient blue PeLEDs are still far behind, especially for the blue emission with a wavelength less than 480 nm, which greatly limits their commercialization. 6–10…”