ARPES data for Monolayer Cu2Se on Cu(111).zip

The exciton-dominated optical response in two-dimensional (2D) materials is significant for basic research and practical applications. Here, carrier dynamics and transient band renormalization in monolayer (ML) Cu₂Se grown on Cu(111) are explored by time- and angle-resolved photoemission spectroscopy. The lifetime of the excited carriers for ML Cu₂Se/Cu(111) is found to be as long as 620 fs, which is attributed to the fact that the excitons and the hole barrier layer formed at the interface suppress the ultrafast Auger recombination channel and decelerate the relaxation process of the excited carriers. A concurrent transient increase of the bandgap and the effective mass of the holes after photoexcitation is observed, suggesting an exciton-driven band renormalization effect occurred in the ML Cu₂Se. These findings provide new insights into the photocarrier relaxation process in 2D semiconductors with potential applications in optoelectronic devices.