The epitaxial growth of a perovskite matrix on quantum dots (QDs) has enabled the emergence of efficient red light-emitting diodes (LEDs) because it unites efficient charge transport with strong surface passivation. However, the synthesis of wide-band gap (E g) QD-in-matrix heterostructures has so far remained elusive in the case of sky-blue LEDs. Here, we developed CsPbBr3 QD-in-perovskite matrix solids that enable high luminescent efficiency and spectral stability with an optical E g of over 2.6 eV. We screened alloy candidates that modulate the perovskite E g and allow heteroepitaxy, seeking to implement lattice-matched type-I band alignment. Specifically, we introduced a CsPb1–x Sr x Br3 matrix, in which alloying with Sr2+ increased the E g of the perovskite and minimized lattice mismatch. We then developed an approach to passivation that would overcome the hygroscopic nature of Sr2+. We found that bis(4-fluorophenyl)phenylphosphine oxide strongly coordinates with Sr2+ and provides steric hindrance to block H2O, a finding obtained by combining molecular dynamics simulations with experimental results. The resulting QD-in-matrix solids exhibit enhanced air- and photo-stability with efficient charge transport from the matrix to the QDs. LEDs made from this material exhibit an external quantum efficiency of 13.8% and a brightness exceeding 6000 cd m–2.
Broadband emission with a large Stokes shift is of interest for applications in solid‐state lighting. Such emission is often achieved with self‐trapped excitons; however, in reduced‐dimensional perovskites, high‐performance self‐trapped emission has, until now, been widely observed only in lead‐based materials. Here, the synthesis in an air ambient of reduced‐dimensional Sn‐based perovskite phosphors R2 + xSnI4 + x [R = octylammonium (OTA), hexylammonium (HA) or butylammonium (BA)] is reported, an advance achieved by tailoring the synthesis of the Ruddlesden‐Popper 2D perovskites R2SnI4. The lead‐free R2 + xSnI4 + x phosphors have broadband self‐trapped emission with over 80% photoluminescence quantum yield (PLQY) and more than a 150 nm Stokes shift. White‐light‐emitting diodes (WLEDs) based on OTA2 + xSnI4 + x phosphors exhibit warm‐white emission (correlated color temperature = 2654K) suited to home lighting, and a CRI of 92, among the best for Pb‐free perovskite WLEDs reported to date.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.