Open AccessType‐I Energy Level Alignment at the PTCDA—Monolayer MoS 2 Interface Promotes Resonance Energy Transfer and Luminescence Enhancement
Author(s) -
Park Soohyung,
Mutz Niklas,
Kovalenko Sergey A.,
Schultz Thorsten,
Shin Dongguen,
Aljarb Areej,
Li LainJong,
Tung Vincent,
Amsalem Patrick,
ListKratochvil Emil J. W.,
Stähler Julia,
Xu Xiaomin,
Blumstengel Sylke,
Koch Norbert
Publication year - 2021
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202100215
Subject(s) - heterojunction , picosecond , monolayer , exciton , excited state , materials science , photoluminescence , van der waals force , semiconductor , optoelectronics , luminescence , resonance (particle physics) , molecular physics , atomic physics , chemistry , nanotechnology , molecule , optics , condensed matter physics , physics , laser , organic chemistry
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)‐MoS 2 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‐MoS 2 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‐MoS 2 occurs on a sub‐picosecond time scale. This gives rise to an enhanced PL yield from ML‐MoS 2 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.