Suppressing Growth Strategy on Synthesizing Stable and High-Quality Blue-Emitting CsPbBr₃ Quantum Dots

Abstract

In recent years, deep-blue perovskite light-emitting diodes (PeLEDs) based on ultra-small CsPbBr3 quantum dots (QDs) have attracted increased attention. However, ultra-small CsPbBr3 QDs tend to have more defects and more nonradiative processes because of their ultrafast nucleation and growth rates. How to suppress the nucleation and growth rate is an important issue for developing deep-blue emitting CsPbBr3 QDs with high performance. Herein, a modified hot-injection method (MM) is designed for suppressing the growth process of CsPbBr3. The ligands of oleic acid (OA) and oleylamine (OAm) are employed instead of octadecene (ODE) as the solution, and as a result, the strong confined and high-quality CsPbBr3 QDs (∼4.45 nm) are obtained, presenting strong deep-blue emission (≈465 nm) with a photoluminescence quantum yield (PLQY) of 95%, an average lifetime of 8.84 ns, and a large exciton binding energy of 268.7 meV, which can maintain blue emission over 30 days under atmospheric conditions. Compared with the CsPbBr3 nanocubes (NCs) obtained by the common hot-injection method (CM), the CsPbBr3 QDs obtained by MM have fewer defects and trap states, resulting in less nonradiative processes. In addition, the fabricated PeLEDs based on the above CsPbBr3 QDs show deep-blue emission with Commission Internationale de l’Eclairage (CIE) color coordinates of (0.129 and 0.074), which is better than the blue standard of the National Television Standards Committee (NTSC). Evidently, this work provides a way to synthesize ultra-small CsPbBr3 QDs and also reflects the important influence of the reaction solvent on perovskite synthesis.

Hot Carrier Trapping and It's Influence to the Carrier Diffusion in CsPbBr3 Perovskite Film Revealed by Transient Absorption Microscopy

“…The XRD pattern of both films contains three main peaks at 15.2 ° , 21.6 °, and 30.7 ° , which are attributed to the (100), (110), and (200) faces, respectively. [ 8 , 10 ]…”

Influence of Binary Ligands in Designing Cesium Lead Halide (CsPbX3, X = Cl, Br, I) Perovskite Nanocrystals-Oleic Acid and Oleylamine

“…Here, uniform NW distribution is achieved using an OA/OAm ratio of 2. Interestingly, Li et al have synthesized ultrasmall OA/OAm-capped CsPbBr 3 QDs (~4.5 nm) with high exciton binding energy (E b = 268.7 meV) using a high OA concentration without 1-ODE [69]. However, by varying the concentration of OA/OAm in the presence of 1-ODE, Liang et al achieved QDs (2.4 nm) for the ratio 0.6 mL/0.3 mL, whereas NPLs and NSs morphologies were achieved for the ratios 0.5 mL/0.5 mL and 0.2 mL/0.8 mL [70].…”