Carrier Multiplication in Transition Metal Dichalcogenides Beyond Threshold Limit.

ABSTRACT: Carrier multiplication (CM), multiexciton generation by absorbing a single photon, enables disruptive improvements in photovoltaic conversion efficiency. However, energy conservation constrains the threshold energy to at least twice bandgap (2 Eg$ E_\text{g}$ ). Here, a below threshold limit CM in monolayer transition metal dichalcogenides (TMDCs) is reported. Surprisingly, CM is observed with excitation energy of only 1.75 Eg$E_\text{g}$ due to lattice vibrations. Electron-phonon coupling (EPC) results in significant changes in electronic structures, which favors CM. Indeed, the strongest EPC in monolayer MoS₂ leads to the most efficient CM among the studied TMDCs. For practical applications, chalcogen vacancies can further lower the threshold by introducing defect states withi

SUBMITTER: Liu Y 

PROVIDER: S-EPMC9631089 | biostudies-literature | 2022 Nov

REPOSITORIES: biostudies-literature