Benzyl alcohol-treated CH3NH3PbBr3 nanocrystals exhibiting high luminescence, stability, and ultralow amplified spontaneous emission thresholds

• Main Authors: Veldhuis, Sjoerd Antonius, Tay, Eugene Yong Kang, Bruno, Annalisa, Dintakurti, Sai S. H., Bhaumik, Saikat, Muduli, Subas Kumar, Li, Mingjie, Mathews, Nripan, Sum, Tze Chien, Mhaisalkar, Subodh Gautam
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Science::Physics; Perovskites; Quantum Dots
• Online Access: https://hdl.handle.net/10356/141120
• Institution: Nanyang Technological University

We report the high yield synthesis of about 11 nm sized CH3NH3PbBr3 nanocrystals with near-unity photoluminescence quantum yield. The nanocrystals are formed in the presence of surface-binding ligands through their direct precipitation in a benzyl alcohol/toluene phase. The benzyl alcohol plays a pivotal role in steering the surface ligands binding motifs on the NC surface, resulting in enhanced surface-trap passivation and near-unity PLQY values. We further demonstrate that thin films from purified CH3NH3PbBr3 nanocrystals are stable >4 months in air, exhibit high optical gain (about 520 cm-1), and display stable, ultralow amplified spontaneous emission thresholds of 13.9 ± 1.3 and 569.7 ± 6 μJ cm-2 at one-photon (400 nm) and two-photon (800 nm) absorption, respectively. To the best of our knowledge, the latter signifies a 5-fold reduction of the lowest reported threshold value for halide perovskite nanocrystals to date, which makes them ideal candidates for light-emitting and low-threshold lasing applications.