Strongly-Confined Small-Size Perovskite Quantum Dots for Pure-Color Light Emitting Diodes

Perovskite quantum dots (PQDs) are a promising candidate for next-generation displays owing to their tunable spectra and narrow linewidth. The mixed-halide perovskites applied in their light-emitting diodes (LEDs) and pure-color displays show unstable spectra due to halide segregation, which can be avoided by using single-halide I-based and Br-based PQDs with strong confinement effects. In this review, the development of strongly confined PQDs for pure-color LEDs is summarized. Focusing on the confinement effect, the unique exciton behaviors and corresponding possible effect on the LEDs, alongside summarizing the applied methods to regulate the perovskite particle sizes, are presented. Then, the low conductivity of confined PQDs with excessive insulating ligands or matrix is analyzed, and the corresponding strategies proposed to increase the carrier injection are listed. Subsequently, some effective fabrication innovations to improve the performance of LEDs are concluded. With the presentation of the development trend of pure-red and pure-blue LEDs, some challenges and opportunities on the understanding of the mechanism, redshift during the post-treatment, and device efficiency improvement are proposed in the last part.