Plasmon-enhanced S2 electroluminescence from the high-lying excited state of a single porphyrin molecule
| Autor: | Zhen-Chao Dong, Yuan Liao, Fan-Fang Kong, Shi-Hao Jing, Yun-Jie Yu, Xiao-Jun Tian, Yang Zhang, Yao Zhang, Xian-Biao Zhang |
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| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Materials science Physics and Astronomy (miscellaneous) Physics::Optics 02 engineering and technology Substrate (electronics) Electroluminescence 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics Condensed Matter::Materials Science Excited state 0103 physical sciences Physics::Atomic and Molecular Clusters Surface plasmon resonance 0210 nano-technology Luminescence Plasmon Excitation Quantum tunnelling |
| Zdroj: | Applied Physics Letters. 117:243301 |
| ISSN: | 1077-3118 0003-6951 |
| DOI: | 10.1063/5.0027291 |
| Popis: | We demonstrate the B-band electroluminescence from the high-lying S2 excited state of a single zinc porphyrin molecule with the scanning tunneling microscope-induced luminescence technique by using an aluminum tip. The nanocavity plasmon mode is found to be critical for the occurrence of S2 electroluminescence. When using a silver tip to excite the molecule electronically decoupled from the Ag(100) substrate by an ultrathin sodium chloride spacer, we only observe the Q-band electroluminescence originating from the radiative decay of the S1 first excited state, without any B-band emission due to the lack of effective plasmonic enhancement for the B-band. However, when the nanocavity plasmon resonance is tuned to a bluer range by using an aluminum tip, the S2 electroluminescence from a single zinc porphyrin shows up because the nanocavity plasmon mode can now spectrally overlap with the B-band emission to generate efficient plasmonic enhancement for the radiative decay directly from the S2 state. Interestingly, the excitation mechanisms for these two types of emission are found to be different. While the Q-band emission is attributed mainly to a carrier-injection mechanism, the B-band electroluminescence is found to be excited via an inelastic electron scattering process. Our results open a route to investigate the photophysical property and dynamic behavior of isolated molecules in their excited states. |
| Databáze: | OpenAIRE |
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