Photocarrier Dynamics in MoTe2 Nanofilms with 2H and Distorted 1T Lattice Structures.

Molybdenum telluride (MoTe2), an emerging layered two-dimensional (2D) material, possesses excellent phase-changing properties. Previous studies revealed its reversible transition between 2H and 1T' phases with a transition energy as small as 35 meV. Since 1T'-MoTe2 is metallic, it can serve as an electrical contact for semiconducting 2H-MoTe2-based optoelectronic devices. Here, the photocarrier dynamics in MoTe2 nanofilms synthesized by a one-step method and with coexisting multiple phases are investigated by transient absorption measurements. Both the energy relaxation time and the recombination lifetime of the excitons are shorter in the 1T'-MoTe2 compared to its 2H phase. These results provide information on the different photocarrier dynamical properties of these two phases, which is important for future 2D optoelectronic and phase-change electronic devices based on MoTe2.