Modulating optical properties and interfacial electron transfer of CsPbBr3 perovskite nanocrystals via indium ion and chlorine ion co-doping

Enhancing Optical and Thermal Stability of Blue-Emitting Perovskite Nanocrystals through Surface Passivation with Sulfonate or Sulfonic Acid Ligands

This study aims to enhance the optical and thermal properties of cesium-based perovskite nanocrystals (NCs) through surface passivation with organic sulfonate (or sulfonic acid) ligands. Four different phenylated ligands, including sodium β-styrenesulfonate (SbSS), sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (SPTS), and 4-dodecylbenzenesulfonic acid (DBSA), were employed to modify blue-emitting CsPbBr1.5Cl1.5 perovskite NCs, resulting in improved size uniformity and surface functionalization. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the successful anchoring of sulfonate or sulfonic acid ligands on the surface of perovskite NCs. Moreover, the photoluminescence quantum yield increased from 32% of the original perovskite NCs to 63% of the SPTS-modified ones due to effective surface passivation. Time-resolved photoluminescence decay measurements revealed extended PL lifetimes for ligand-modified NCs, indicative of reduced nonradiative recombination. Thermal stability studies demonstrated that the SPTS-modified NCs retained nearly 80% of the initial PL intensity when heated at 60 °C for 10 min, surpassing the performance of the original NCs. These findings emphasize the optical and thermal stability enhancement of cesium-based perovskite NCs through surface passivation with suitable sulfonate ligands.

Mechanical milling processed highly luminescent Cs-Pb-Br perovskite emitters

We report well-dispersed highly emitting perovskite emitters synthesized via the surfactant-assisted ball-milling method. Both the emitting peaks and the colour purity of the synthesized perovskite emitters can be effectively tuned through additive functionalization and precursor engineering.

Pressure-Induced Bifurcation in the Photoluminescence of Red Carbon Quantum Dots: Coexistence of Emissions from Surface Groups and Nitrogen-Doped Cores

Carbon quantum dots (CDs) with favorable fluorescent properties have stimulated considerable effort to modulate their photoluminescence (PL) for bioimaging and sensing. However, the fluorescent mechanisms are still only partially understood due to the diverse physicochemical properties of CDs prepared by various synthesis methods and postpreparation processes. In this report, pressure-induced bifurcation of PL is reported in red carbon quantum dots (R-CDs) for the first time. The splitting of PL into an irreversible blue-shifted peak and a reversible red-shifted peak under pressure suggests the coexistence of multiple fluorescent mechanisms in R-CDs, i.e., emissions from surface groups and nitrogen-doped cores. The concentration and excitation laser energy dependencies of pressure-induced bifurcation, as well as the time-resolved PL, further support the coexistence of multiple emitters. Our results provide a method for distinguishing between the different fluorescent mechanisms related to surface groups and carbon cores in CDs.

Research on the stability of luminescence of CsPbBr3 and Mn:CsPbBr3 PQDs in polar solution

Mn:CsPbBr₃ PQDs are achieved by hot injection method. As the amount of Mn doping is gradually increased, the photoluminescence (PL) spectra shows a slight blue shift. Mn-doped PQDs exhibit higher quantum efficiency of 83.9% and longer lifetimes of 267 ns. The stability test was performed to assess the susceptibility of the PQDs to polar solutions. It was figured out that although the stabilities of CsPbBr₃ PQDs and Mn-doped PQDs decreased as the polarity of solution increased, Mn-doped PQDs still maintained higher PL intensity than undoped PQD. Notably, 73% PL intensity of Mn:PQDs was maintained which is nearly three times as much as undoped PQDs in water. We found polarity would induce drastic degradation of CsPbBr₃ QDs. The steady-state spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) verified that CsPbBr₃ QDs tend to aggregate to form larger particles under continuous light soaking. Our work reveals the main origin of instability in CsPbBr₃ QDs and provides reference to engineering such QDs towards optimal device application.

Mn-doped PQDs exhibit higher quantum efficiency of 83.9%. The stabilities of CsPbBr₃ PQDs and Mn-doped PQDs decreased as the polarity of solution increased, but Mn-doped PQDs still maintained higher PL intensity than undoped PQDs.