Thermally Activated Delayed Near‐Infrared Photoluminescence from Functionalized Lead‐Free Nanocrystals

• Published in: Angewandte Chemie International Edition Vol. 62; no. 6; pp. e202217287 - n/a
• Main Authors: He, Shan, Du, Jun, Liang, Wenfei, Zhang, Boyu, Liang, Guijie, Wu, Kaifeng
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.02.2023
• Edition: International ed. in English
• Subjects: Controllability; Copper indium selenides; Crystals; Energy harvesting; Energy Transfer; Excitons; Fluorescence; Lead-Free Nanocrystals; Ligands; Luminescence; Nanocrystals; Near-Infrared Emission; Organic chemistry; Photoluminescence; Photons; Quantum dots; Room temperature; Thermally-Activated Delayed Emission; Time-Resolved Spectroscopy; Visible spectrum; Lead-Free Nanocrystals; Energy Transfer; Near-Infrared Emission; Thermally-Activated Delayed Emission; Time-Resolved Spectroscopy
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202217287

As an analogue to thermally activated delayed fluorescence (TADF) of organic molecules, thermally activated delayed photoluminescence (TADPL) observed in molecule‐functionalized semiconductor nanocrystals represents an exotic mechanism to harvest energy from dark molecular triplets and to obtain controllable, long‐lived PL from nanocrystals. The reported TADPL systems have successfully covered the visible spectrum. However, TADF molecules already emit very efficiently in the visible, diminishing the technological impact of the less‐efficient nanocrystal‐molecule TADPL. Here we report bright, near‐infrared TADPL in lead‐free CuInSe2 nanocrystals functionalized with carboxylated tetracene ligands, which results from efficient triplet energy transfer from photoexcited nanocrystals to ligands, followed with thermally activated reverse energy transfer from ligand triplets back to nanocrystals. This strategy prolonged the nanocrystal exciton lifetime from 100 ns to 60 μs at room temperature. Efficient thermally‐activated delayed near‐infrared photoluminescence has been achieved in lead‐free CuInSe2‐based nanocrystals surface‐functionalized with tetracene ligands, prolonging the exciton lifetime to 60 μs at room temperature. Such long‐lived near‐infrared emission may find an array of applications.