Halide-Rich Synthesized Cesium Lead Bromide Perovskite Nanocrystals for Light-Emitting Diodes with Improved Performance

Abstract

To improve the quality and durability of inorganic halide perovskite nanocrystals (NCs), ammonium halide and lead oxide (PbO) were separately employed for the synthesis of NCs with a tunable ratio of metal to halide. The halide-rich circumstance was therefore successfully set up and found to be beneficial for obtaining good quality NCs with high photoluminescence quantum yields and remarkable stability against purification compared to those qualities of previous regular methods with lead halide. The fabricated light-emitting diode (LED) devices with NCs made in a halide-rich circumstance demonstrated performance better than that of devices with NCs made in a halide-poor circumstance. A LED with CsPbBr 3 NCs with a 1:4 Pb:Br ratio showed an obvious improved maximal luminance of 12090 cd m −2 , a current efficiency of 3.1 cd A −1 , and an external quantum efficiency of 1.194%, which were much higher than those of devices with NCs synthesized by the regular method.

Perovskite Quantum Dots and Their Application in Light‐Emitting Diodes

“…Resulting device showed the highest EQE of 6.27%, which is 50‐fold enhanced compared with the first CsPbBr 3 QLEDs. Recently, Liu et al discovered that CsPbBr 3 PQDs showed less electron trap state with the increasing Br content. The schematic of Br‐rich and Br‐poor condition for synthesis was shown in Figure c, the CsPbBr 3 PQDs were surrounded by oleylammonium bromide as a passivation layer.…”

“…Copyright 2016, Wiley‐VCH). c) Schematic of halide‐poor and halide‐rich conditions for synthesis of CsPbBr 3 PQDs (Reproduced with permission . Copyright 2017, American Chemical Society).…”

Highly Luminescent Lead Halide Perovskite Quantum Dots in Hierarchical CaF2 Matrices with Enhanced Stability as Phosphors for White Light‐Emitting Diodes

“…[7] Colloidal quantum dots (QDs) such as CdSe, [8,9] InP, [10] and PbS [11] have been regarded as a new class of luminescent materials due to their high chemical stability, high PL QY, and tunable emission wavelengths which can easily cover the whole visible region by varying their size or dimension. [22][23][24][25][26][27][28][29] Despite these advantages of PQDs, the intrinsic instability and poor durability of the perovskite severely hamper the practical applications, which causes a huge technical obstacle for commercialization. [12][13][14][15][16][17][18][19][20][21] The high quantum efficiency, high color purity, and facile preparation make them as promising candidates for LED or backlight downconverters for LCDs.…”

Metal Halide Perovskites: Synthesis, Ion Migration, and Application in Field‐Effect Transistors

“…Via the analysis of transmission electron microscope (TEM) images, the presence of lead nanoparticles in the solution before the injection of Cs, and the observation of a spherical lead particle in every observed CsPbX 3 nanoparticle can strongly indicate that the CsPbX 3 nanoparticles are seeded by the lead nanoparticles . Moreover, a variety of critical factors in the HI method have been discussed in detail in recent publications, such as the surface ligand, reaction temperature, halide‐rich circumstance, and solvent polarity …”