Surface Halogen Compensation for Robust Performance Enhancements of CsPbX₃ Perovskite Quantum Dots

Abstract

Understanding the subtle structure–property relationships of quantum dots (QDs) is essential for targeted modulation of optoelectronic properties, and the influences of surface defects of inorganic halide perovskite (HP) QDs are still not very clear. Here, the negative exciton trapping effects of surface halide vacancies (VX) on the photoluminescence quantum yield QY (PLQY) of HPQDs are determined by a detailed analysis of the optical parameters, exciton dynamics, and surface chemical states. Based on the fact that VX contribute greatly to nonradiative recombination processes, versatile in situ and postpassivation strategies are developed by constructing intact Pb–X octahedrons. High QYs for standard red CsPbBr1I2 (85%), green CsPbBr3 (96%), and blue CsPbBr1.3Cl1.7 (92%) emissions are achieved. The superiorities of the reduced VX are further demonstrated by high external quantum efficiency of 0.8% and a stable emission wavelength of the blue light‐emitting diodes. This study deepens the understanding of HPQDs and demonstrates the potential for the artificial control of the optical properties of HPQDs.

CsPbBr3 Quantum Dots 2.0: Benzenesulfonic Acid Equivalent Ligand Awakens Complete Purification

“…On one hand, CsPbBr 3 QDs are terminated with bromide ions and the ammonium interacts with bromide atoms through hydrogen bonds . The formation of hydrogen bonds reduces the coulombic interactions between lead and bromide ions, and then ammonium ligands will fall off from the QD surface along with bromide ions ( Scheme a left) . On the other hand, the deprotonated ammonium ligands cannot interact with the CsPbBr 3 QDs.…”

Lead‐Free Halide Double Perovskites: Structure, Luminescence, and Applications

“…For example, high‐quality OIHP nanocrystals (NCs) with near‐unity PL QY and narrow full width at half maximum (FWHM) could cover the full visible range via either in situ passivation or posttreatment methods. [ 14–19 ] In addition, the external quantum efficiency (EQE) of OIHP LEDs have been promoted to over 20% in green, red, and near‐infrared radiation regions. [ 1,20,21 ] It has been concluded that the high symmetry of the cubic lattice and unique electronic configuration of Pb 2+ (d 10 s 2 ) with inactive 6p orbits play critical roles in determining the optoelectronic properties of OIHPs.…”

Single‐Solvent, Ligand‐Free, Gram‐Scale Synthesis of Cs4PbBr6 Perovskite Solids with Robust Green Photoluminescence

“…[1][2][3][4][5] Currently, CsPbX 3 (with X being single or mixed Cl, Br, and I anions) perovskite quantum dots (QDs) are the most frequently investigated systems because of their high PL quantum yield (PLQY) and chromatogram purity, low-threshold lasing, as well as sharp emission line-width. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Unfortunately, CsPbX 3 perovskite QDs are sensitive to the external environments such as polar solvents, moisture, heat, and light, which usually destroy their structure and degrade their performances. [21][22][23][24][25][26][27][28] These issues greatly impede their developments towards practical applications.…”

“…All‐inorganic luminescent perovskite materials have been an active research area in recent years for their superior photoluminescence (PL) properties and potential applications in display, lighting, light‐emitting diodes, optoelectronic detector, lasing, anti‐counterfeiting code, etc . Currently, CsPbX 3 (with X being single or mixed Cl, Br, and I anions) perovskite quantum dots (QDs) are the most frequently investigated systems because of their high PL quantum yield (PLQY) and chromatogram purity, low‐threshold lasing, as well as sharp emission line‐width . Unfortunately, CsPbX 3 perovskite QDs are sensitive to the external environments such as polar solvents, moisture, heat, and light, which usually destroy their structure and degrade their performances .…”