Hot Carrier Transfer in PtSe₂/Graphene Enabled by the Hot Phonon Bottleneck

Abstract

The charge transfer (CT) process of two-dimensional (2D) graphene/transition metal dichalcogenides (TMDs) heterostructures makes the photoelectric conversion ability of TMDs into a wider spectral range for the light harvester and photoelectric detector applications. However, the direct in situ investigation of the hot carrier transport in graphene/TMDs heterostructures has been rarely reported. Herein, using the optical pump and a terahertz (THz) probe (OPTP) spectroscopy, the CT process from graphene to five-layer PtSe2 in the PtSe2/graphene (P/G) heterostructure is demonstrated to be related to the pump fluence, which is enabled by the hot phonon bottleneck (HPB) effect in graphene. Furthermore, the frequency dispersion conductivity and the THz emission spectroscopy of the P/G heterostructure confirmed the existence of interlayer CT and its pump fluence-dependent behavior. Our results provide in-depth physical insights into the CT mechanism at the P/G van der Waals interface, which is crucial for further exploration of optoelectronic devices based on P/G heterostructures.

Regulating Terahertz Photoconductivity in Two-Dimensional Materials

“…Later, in 2022, Quan et al investigated this charge transfer method caused by carrier aggregation. It was found that it could be related to the charge transfer process caused by the thermal phonon bottleneck effect in graphene, with the analysis of the scattering time and the Smith parameter in the heterostructure, as shown in Figure 2b [105].…”

Auger‐Assisted Secondary Hot Carrier Transfer in a Type I MoS2/PtSe2 Heterostructure

“…Previous reports have shown, however, that in graphene/TMD (including MoS 2 , WS 2 , WSe 2 , and PtSe 2 ) heterostructures, carriers can be promoted from graphene to TMDs under subbandgap excitation (that is, only graphene is excited). [21,30,[39][40][41] This is attributed to hot carriers generated after carrier-carrier scattering in graphene, which have sufficient energy to be transferred to the CB of TMDs. We believe that the same mechanism can account for our experimental observation, i.e., the hot electrons in the CB of PtSe 2 are transferred to the CB of MoS 2 immediately after optical excitation.…”