Post-annealing effect on the structural and optical properties of electrophoretically coated 2D-Layered MoSe2

Temperature dependent changes in the structural, nanomorphological and optical characteristics of the 2D layered molybdenum diselenide (MoSe2), processed by electrophoretic coating (EPC) method, were examined. EPC processed MoSe2 was subjected to Raman spectroscopy confirming distinct active modes of A1g, E11g and E22u at 240.9 cm−1, 282.53 cm−1 and 337.7 cm−1, respectively. The in- and out-of plane vibrational modes observed in the Raman spectra were asserted as the 2H–MoSe2 phase which was not affected by the post annealing temperature. X-ray photoelectron spectroscopic measurements confirmed the states of Mo 3d at 228.9 eV and 232.1 eV, and of Se 3d at 54.5 eV and 55.3 eV. Studies on the surface morphology of the EPC processed MoSe2 showed significant changes due to the post-annealing treatment performed at 150 °C, 250 °C and 350 °C in terms of morphology, flake-size distribution and compactness of the film. The samples annealed at 150 °C and 250 °C showed a better optical absorption in the visible and the near infrared spectral regions with dominant characteristic peaks at 691.2 nm and 801.6 nm. Further studies assured that the EPC process yielded good quality and large area MoSe2 films with exotic structural, optical and nanomorphological characteristics that are highly suitable for functional devices.