Interface engineering and heterometal doping Cu3Se2/WSe2 for efficient charge transfer and nonlinear optical performance

Abstract

Integrating interface engineering and precious heterometal doping with semiconductors is a feasible pathway to construct efficient charge transfer and improve the nonlinear optical (NLO) performance of materials. Here, we report a bimetallic selenide type-II heterostructure of Cu3Se2/WSe2 (CWS) with a simple one-step magnetron co-sputtering of Cu and WSe2 targets at low argon flow rates. Se first nucleates and precipitates to form nanospheres at low flow rates. Due to the electronegativity of Cu being greater than that of W and Cu prioritizes attachment to the outside of the Se nanospheres and promotes the formation of the nanorods-grown Cu3Se2. A combined analysis of X-ray photoelectron spectroscopy and X-ray diffraction data was used to investigate the minor shift in the W 4 f/Se 2p ratio revealing that electrons shifted from Cu3Se2 to WSe2. The diffraction peaks of CWS and the valence electronic structure of Cu1+/Cu2+ confirmed the implantation of Cu3Se2 nanorods on WSe2. The NLO properties of CWS composite films were modulated by varying the power of Cu. More importantly, the nonlinear absorption coefficient of the CWS composite films formed after Cu3Se2 promotion is much better than that of other unmodified pure WSe2 films. The photogenerated carrier dynamics of CWS composite films were investigated by femtosecond transient absorption spectroscopy, and density functional theory calculations show that CWS composite films inhibit efficient electron transfer photogenerated carrier complexation. This work proposes a few strategies for designing heterogeneous structures with interface engineering and precious metal doping to promote adjustable electron transfer dynamics and achieve high NLO conversion efficiency.