期刊
ADVANCED SCIENCE
卷 8, 期 12, 页码 -出版社
WILEY
DOI: 10.1002/advs.202100215
关键词
energy level alignment; energy transfer; MoS2; organic semiconductors; photoelectron spectroscopy; photoluminescence; transient absorption spectroscopy
资金
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) [182087777 - SFB 951]
- National Research Foundation (NRF) of Korea [2018M3D1A1058793]
- Ministry of Trade, Industry and Energy Korea [20012502]
- King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) [OSR-2018-CARF/CCF-3079]
- Open Access Publication Fund of Humboldt-Universitat zu Berlin
- Korea Evaluation Institute of Industrial Technology (KEIT) [20012502] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
The research reveals that PTCDA/ML-MoS2 formed a straddling type-I level alignment supported by insulating sapphire, with PTCDA having the wider energy gap. Resonance energy transfer from PTCDA to ML-MoS2 occurs on a sub-picosecond time scale, enhancing the PL yield from ML-MoS2 and modulating the photoresponse accordingly.
Van der Waals heterostructures consisting of 2D semiconductors and conjugated molecules are of increasing interest because of the prospect of a synergistic enhancement of (opto)electronic properties. In particular, perylenetetracarboxylic dianhydride (PTCDA) on monolayer (ML)-MoS2 has been identified as promising candidate and a staggered type-II energy level alignment and excited state interfacial charge transfer have been proposed. In contrast, it is here found with inverse and direct angle resolved photoelectron spectroscopy that PTCDA/ML-MoS2 supported by insulating sapphire exhibits a straddling type-I level alignment, with PTCDA having the wider energy gap. Photoluminescence (PL) and sub-picosecond transient absorption measurements reveal that resonance energy transfer, i.e., electron-hole pair (exciton) transfer, from PTCDA to ML-MoS2 occurs on a sub-picosecond time scale. This gives rise to an enhanced PL yield from ML-MoS2 in the heterostructure and an according overall modulation of the photoresponse. These results underpin the importance of a precise knowledge of the interfacial electronic structure in order to understand excited state dynamics and to devise reliable design strategies for optimized optoelectronic functionality in van der Waals heterostructures.
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