Dominant Role of Momentum-Forbidden Dark Excitons in the Energy Transfer between Quantum Dots and Monolayer Transition-Metal Dichalcogenides

Jhen-Dong Lin^a, Ping-Yuan Lo^a, Guan-Hao Peng^a, Wei-Hua Li^a, Shun-Jen Cheng^a

^aDepartment of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of Asia-Pacific Conference on Perovskite, Organic Photovoltaics&Optoelectronics (IPEROP25)

Kyoto, Japan, 2025 January 20th - 21st

Organizers: Atsushi Wakamiya, Hideo Ohkita and Seigo Ito

Poster, Jhen-Dong Lin, 052
Publication date: 17th October 2024

In this work, we present a first-principles-based theoretical investigation of the exciton-mediated Förster resonant energy transfers (FRETs) from photoexcited quantum dots (QDs) to monolayer transition-metal dichalcogenides (ML-TMDs), inspired by recent experimental observations of near-unity efficiencies of FRET in TMD-ML systems [1-5]. The FRET studies are based on the first-principles-calculated band dispersions and fine structures of excitons in variety, comprising bright exciton (BX) and various dark exciton (DX) states, of TMD-MLs by using the efficient in-house code for solving the Bethe-Salpeter equation (BSE) in the basis of maximally localized Wannier functions (MLWF’s) [6]. As a main result, we show that the energy-transfer responses of atomically thin TMD-MLs are dictated by the momentum-forbidden dark excitons (MF-DXs) rather than the commonly recognized BXs [6]. In particular, the longitudinal MF-DX states following the exchange-driven light-like linear band dispersion plays a key role in the superior efficiency and robustness of FRET of TMD-ML against the inhomogeneity of QD-donor ensembles. Consequently, the energy transfer processes in atomically thin 2D materials no longer adhere to the conventional d^-4 distance power law for the FRET between 0D and 2D systems, nor does it manifest the dimensionality of the donor-acceptor system in an expected manner. This finding in discrepancy from classical FRET model brings us a new insight into FRET dynamics in TMD-MLs, associated with the unusual momentum and dipole nature of MF-DXs.

References:

[1] Prins, F.; Goodman, A. J.; Tisdale, W. A. Reduced Dielectric Screening and Enhanced Energy Transfer in Single- and Few-Layer MoS2. Nano Lett. 2014 14, 6087-6091.

[2] Taghipour, N.; Martinez, P. L. H.; Ozden, A.; Olutas, M.; Dede, D.; Gungor, K.; Erdem, Onur; Perkgoz, N. K.; Demir, H. V. Near-Unity Efficiency Energy Transfer from Colloidal Semiconductor Quantum Wells of CdSe/CdS Nanoplatelets to a Monolayer of MoS2. ACS Nano 2018 12, 8547-8554.

[3] Gough, J. J.; McEvoy, N.; O'Brien, M.; Bell, A. P.; McCloskey, D.; Boland, J. B.; Coleman, J. N.; Duesberg, G. S.; Bradley, A. L. Dependence of Photocurrent Enhancements in Quantum Dot (QD)-Sensitized MoS2 Devices on MoS2 Film Properties. Adv. Funct. Mater. 2018 28, 1706149.

[4] Wu, L.; Chen, Y.; Zhou, H.; Zhu, H. Ultrafast Energy Transfer of Both Bright and Dark Excitons in 2D van der Waals Heterostructures Beyond Dipolar Coupling. ACS Nano 2019 13, 2341-2348.

[5] Tai, Y.-C.; Tzeng, W.-Y.; Lin, J.-D.; Kuo, Y.-H.; Chen, F.-X. R.; Tu, R.-J.; Huang, M.-Y.; Pai, S.-S.; Chang, N. W.; Tseng, S.-Y.; Chen, C.; Lin, C.-L.; Yabushita, A.; Cheng, S.-J.; Luo, C.-W. Directly Unveiling the Energy Transfer Dynamics between Alq3 Molecules and Si by Ultrafast Optical Pump–Probe Spectroscopy. Nano Lett. 2023 23, 10490-10497.

[6] Lin, J.-D.; Lo, P.-Y.; Peng, G.-H.; Li, W.-H.; Huang, S.-Y.; Chen, G.-Y.; Cheng, S.-J. Essential role of momentum-forbidden dark excitons in the energy transfer responses of monolayer transition-metal dichalcogenides. npj 2D Mater. Appl. 2023 7, 51.

Acknowledgements:

The authors thank the National Center for High-performance Computing (NCHC) for providing computational and storage resources, which are used in this work. This work is also partially or fully supported by the National Science and Technology Council of Taiwan under the contract, MOST 109-2112-M-009-018-MY3, MOST 111-2112-M-A49-014, MOST 110-2112-M-005-002, MOST 111-2123-M-006-001 and by National Center for Theoretical Sciences (NCTS) of Taiwan. The authors would like to thank Prof. Chih-Wei Luo, Prof. Chun-Liang Lin, and Mr. Yu-Chan Tai for the fruitful discussions.

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