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MM: Fachverband Metall- und Materialphysik
MM 10: Materials for Storage and Conversion of Energy: New Storage Materials
MM 10.3: Talk
Monday, March 27, 2023, 16:15–16:30, SCH A 215
Carrier Multiplication in Transition Metal Dichalcogenides Beyond Threshold Limit — •Yuxiang Liu1, Thomas Frauenheim1, and ChiYung Yam2 — 1Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany — 2Shenzhen Institute for Advanced Study, University of Electronic Science and Technology of China, Shenzhen, 518000, China
Carrier multiplication (CM), multiexciton generation by absorbing a single photon. Beard et al. predicted that CM could overcome the Schokley-Queisser limit and raise solar cell efficiency to ~46%[1]. The current state-of-the-art nanomaterials including quantum dots and carbon nanotubes have demonstrated CM phenomenon, but not satisfactory owing to high threshold energy and inherent difficulties with carrier extraction. We found a below threshold limit CM in monolayer transition metal dichalcogenides (TMDCs) MX2 (M = Mo, W; X= S, Se, Te). Surprisingly, the threshold energy of CM in monolayer TMDCs can be substantially reduced due to lattice vibrations. Electron-phonon couplings (EPC) could cause significant changes in electronic structures, even trigger semiconductor-metal transition, and eventually decrease the threshold energy of CM to less than twice bandgap[2]. Our results identify TMDCs as attractive candidate materials for efficient optoelectronic devices with the advantages of high photoconductivity and phonon-assisted tunable CM characteristics.
Reference [1] Beard, M. C., et al., Acc. Chem. Res.,46, 1252--1260(2013). [2] Yuxiang L., et al., Adv. Sci., 9, 2203400 (2022).