Fig. 3: Ultrafast interfacial hot electron transfer and relaxation dynamics in VSe2/Bi2Se3.

a 2D plots of the transient reflectance (TR) spectra of 10 quintuple layer (QL) Bi2Se3, bare VSe2 film, and 118 nm VSe2/Bi2Se3 Heterostructure (VBH). b TR traces at each sample around 0.9 eV probe energy. The thermalization time (τtherm) of bare VSe2 and decay time of phonon-assisted bulk-surface scattering (τ1, red curves) are listed. The stages of (i) and (ii) indicate the processes of ultrafast carrier dynamics in Bi2Se3. The CB, VB, and SS means conduction band, valence band, and surface state, respectively. c Schematic of band alignment and hot electron transfer dynamics in VBHs and. Each characteristic energy of the work function (W) of VSe2, electron affinity (\({{{{{\rm{\chi }}}}}}\)), and bandgap (Eg) of Bi2Se3 is shown according to previous studies11,14,62.