Holy Water: Photo‐Brightening in Quasi‐2D Perovskite Films under Ambient Enables Highly Performing Light‐Emitting Diodes. (8th December 2022)

• Record Type: Journal Article
• Authors: Duan, Yanyan; Oropeza, Freddy E.; Jin, Xueze; Amargós‐Reyes, Olivia; Atoini, Youssef; Cavinato, Luca M.; Nagy, Gergely Norbert; Kahaly, Mousumi Upadhyay; de la Peña O'Shea, Víctor A.; Wang, De‐Yi; Costa, Rubén D.
• Is Part Of: Advanced functional materials. Volume 33:Number 7(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-08
• Subjects: ambient storages -- light‐emitting diodes -- photo‐brightening -- quasi‐2D perovskite -- water passivation; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202209249
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Quasi‐2D perovskites provide new opportunities for lighting and display applications due to their high radiative recombination and excellent stability. However, seldom attention has been placed on their self‐stability/working operation under ambient storage. Herein, quasi‐2D perovskites/Polyethylene oxide (PEO) films are studied, showing an unforeseen photo‐brightening effect under ambient storage (i.e., an increase of the photoluminescence quantum yield from 55% to 74% after 100 days). In stark contrast, those stored under a dark/inert atmosphere show a significant decrease down to 38%. This counterintuitive phenomenon responds to the increasing radiative recombination rate caused by the passivation of the surface Br vacancies in the presence of physically adsorbed water molecules, as corroborated by in situ/ex situ X‐ray photoelectron spectroscopy and density functional theory calculations. Capitalizing on this surprising effect, stable light‐emitting diodes (LEDs) using quasi‐2D perovskites/PEO color filters are fabricated, realizing high stabilities of ≈400 h@10 mA under operating ambient conditions, representing a 20‐fold enhancement compared to LEDs with 3D counter partners. Hence, this study reveals a unique insight into the impact of water passivation on the optical/structural properties of quasi‐2D perovskite films, broadening their applications under operating ambient conditions. Abstract : Photo‐brightening is observed in quasi‐2D perovskite films upon ambient storage, which is attributed to the moisture passivation effect that repairs the surface Br vacancies in a dynamic adsorption/desorption process. The presence of these Br vacancies and the passivation effect of H2 O molecules can be directly confirmed by the in situ/ex situ XPS measurements and the DFT calculations.