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Excited-State THz Vibrations in Aggregates of PtII Complexes Contribute to the Enhancement of Near-Infrared Emission Efficiencies** |
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| Authors: | Yu-Chen Wei Bo-Han Chen Ren-Siang Ye Hsing-Wei Huang Jia-Xuan Su Chao-Yang Lin Justin Hodgkiss Lian-Yan Hsu Yun Chi Kai Chen Chih-Hsuan Lu Shang-Da Yang Pi-Tai Chou |
| Institution: | 1. Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan;2. Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013 Taiwan
These authors contributed equally to this work.;3. Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013 Taiwan;4. Robinson Research Institute, Faculty of Engineering, Victoria University of Wellington, Wellington, 6012 New Zealand;5. MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6010 New Zealand;6. Department of Chemistry, National Taiwan University, Taipei, 10617 Taiwan Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617 Taiwan National Center for Theoretical Sciences, Taipei, 10617 Taiwan;7. Department of Materials Science and Engineering, Department of Chemistry, and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong SAR, Hong Kong |
| Abstract: | The exploration of deactivation mechanisms for near-infrared(NIR)-emissive organic molecules has been a key issue in chemistry, materials science and molecular biology. In this study, based on transient absorption spectroscopy and transient grating photoluminescence spectroscopy, we demonstrate that the aggregated PtII complex 4H (efficient NIR emitter) exhibits collective out-of-plane motions with a frequency of 32 cm−1 (0.96 THz) in the excited states. Importantly, similar THz characteristics were also observed in analogous PtII complexes with prominent NIR emission efficiency. The conservation of THz motions enables excited-state deactivation to proceed along low-frequency vibrational coordinates, contributing to the suppression of nonradiative decay and remarkable NIR emission. These novel results highlight the significance of excited-state vibrations in nonradiative processes, which serve as a benchmark for improving device performance. |
| Keywords: | Aggregation Energy Gaps Excited States NIR Emission PtII Complexes |