Stabilization and Fluorescence Enhancement of CsPbX₃ (X = Cl, Br, I) Perovskite Nanocrystals with Tungstosilicic Acid

Abstract

It is still challenging to achieve both good stability and high PLQYs for perovskite NCs because of their ionic nature and structural defects. In this work, tungstosilicic acid (TSA) is used for the surface passivation of cesium lead halide perovskite NCs. Near-unity PLQY is achieved for CsPbBr3 NCs after surface passivation with a suitable amount of TSA. XRD in conjunction with XPS analysis shows that TSA binds hydrophobic chains of OAm onto the surface of CsPbBr3 NCs. XPS results also demonstrate that TSA passivation can change the charge distribution of the cations on the surface layers, which can enhance the interaction with surface traps. PL decay analysis reveals that trap states arising from the surface defects are significantly decreased after TSA passivation. TSA-passivated CsPbBr3 NCs demonstrate long-term ambient stability and good resistances to polar solvents and maintain about 80% of their initial PL intensity after storage under ambient conditions for 50 days. It is further found that TSA passivation is able to improve the PLQYs of a broad spectrum of CsPbX3 (X = Cl, Br, I) NCs without hindering the tunability of the band gaps and PL colors of CsPbX3 NCs via anion exchange.

Color Turning of One-Dimensional Broadband Emissive Organic Lead Bromide Perovskites

“…The former glows with blue-white light, while the latter is reddish (Figure C,D). For further investigation of colors emitting from perovskites, a white light emitting diode (WLED) was fabricated by laying a silicone gel film containing ppPbBr 3 (20% wt) onto a UV (365 nm) LED chip, which fabrication method was described in our previous work . The difference was that only a single filter is needed here because of the broadband emission property of ppPbBr 3 .…”

Advancements in Perovskite Nanocrystal Stability Enhancement: A Comprehensive Review

“…Inorganic ligands also perform well in the modification of PNCs and the passivation of defects. Zang et al employed tungstosilicic acid for surface modification of cesium lead halide nanocrystals [128]. In this process, TSA binds the hydrophobic chains of OAm to the surface of CsPbBr 3 nanocrystals while altering the charge distribution of the cationic surface layer, thereby enhancing the interaction with surface traps [128].…”

“…Zang et al employed tungstosilicic acid for surface modification of cesium lead halide nanocrystals [128]. In this process, TSA binds the hydrophobic chains of OAm to the surface of CsPbBr 3 nanocrystals while altering the charge distribution of the cationic surface layer, thereby enhancing the interaction with surface traps [128]. TSA-modified CsPbBr 3 nanocrystals demonstrated long-term environmental stability and excellent tolerance to polar solvents.…”

“…TSA-modified CsPbBr 3 nanocrystals demonstrated long-term environmental stability and excellent tolerance to polar solvents. After storage at room temperature for 50 days, approximately 80% of the initial luminescence intensity was maintained [128].…”