Enhanced Photoluminescence and Stimulated Emission in CsPbCl3 Nanocrystals at Low Temperature

• Published in: Journal of physical chemistry. C 2018-11, Vol.122 (43), p.25014-25020
• Main Authors: Lohar, Amruta A, Shinde, Aparna, Gahlaut, Richa, Sagdeo, Archna, Mahamuni, Shailaja
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.8b06579

CsPbCl3 nanocrystals (NCs) are known to show low photoluminescence (PL) quantum efficiency compared to CsPbBr3 NCs. In the present work, at 20 K, stimulated emission is observed from CsPbCl3 NCs at low excitation intensity. Efforts are made to understand the optical behavior and structural properties of chemically grown, 5.3 ± 1.1 nm sized CsPbCl3 NCs. Bulk CsPbCl3 is known to become cubic at 320 K, while, NCs are cubic or tetragonal at room temperature. Temperature dependent PL studies on CsPbCl3 NCs are carried out in a wide temperature range. The primary experimental finding is, about 90 times rise in PL emission intensity and existence of multiple sharp features at low temperature attributable to free exciton, bound excitons, phonon replica along with the defect related emission and stimulated emission. The optical phonon energy is about 26 meV with coupling constant of 54 meV in ∼5.3 nm sized CsPbCl3 NCs. Structural phase transition in CsPbCl3 NCs at about 200 K is also observed.