Low‐Threshold Amplified Spontaneous Emission from Air‐Stable CsPbBr3 Perovskite Films Containing Trace Amounts of Polyethylene Oxide

• Published in: ChemPlusChem (Weinheim, Germany) Germany), 2021-11, Vol.86 (11), p.1537-1543
• Main Authors: Tian, Kun, Lu, Yannan, Liu, Ruqing, Loh, Xian Jun, Young, David James
• Format: Article
• Language: English
• Subjects: amplified spontaneous emission; perovskites; photoluminescence; polyethylene oxide; thin films
• ISSN: 2192-6506; 2192-6506
• DOI: 10.1002/cplu.202100377

Organic additives can enhance the amplified spontaneous emission (ASE) performance of inorganic cesium lead halide perovskites (CsPbBr3) but volatility, potential hygroscopicity and oxidative degradation of these additives jeopardizes the thermal stability and shelf‐life of blended CsPbBr3 films. To address this problem, we have fabricated perovskite films in a two‐step solution protocol involving as little added polyethylene oxide (PEO) as possible. These films exhibited enhanced crystallization, improved photoluminescence (PL) intensity and prolonged lifetimes. Their hierarchical morphology and surface passivation lowered the ASE threshold from 278 to 176 μЈ/cm2 under one‐photon nanosecond laser excitation. The proportion of added PEO was 0.3 wt% and was subsequently almost fully removed, thereby reducing its adverse influence on the stability of resulting films under continuous pulsed laser excitation. Stable ASE spectra could be stimulated after storage in air for 10 months. CsPbBr3 films prepared with only trace amounts of polyethylene oxide (PEO) in a two‐step solution protocol exhibit amplified spontaneous emission (ASE). These films exhibited enhanced crystallization, improved photoluminescence intensity and prolonged shelf‐life. For a CsPbBr3 film without PEO, the threshold of ASE was 278 μ/cm2, and the corresponding gain coefficient was 27.84 cm−1. After introducing a trace of PEO, the ASE threshold reduced to 176 μ/cm2, with a corresponding gain of 32.09 cm−1.