Fig. 1.

PL spectrum and power dependence of encapsulated 1L-WSe₂ at 4 K. a PL spectrum (black curve, linear scale) of encapsulated 1L-WSe₂. Excitation wavelength: 658 nm. The top part of the figure lists the calculated spectral locations of X⁰ (grey), XX⁰ (red) and XX⁻ (blue) in the presence of a screening environment. b Double logarithmic plot of PL intensity as a function of excitation power for X⁰ (black filled circles), XX⁰ (red filled circles) and XX⁻(blue filled circles). The solid curves represent I ∝ P^α for a quadratic (α = 2, red) and linear (α = 1, black) behaviour. The dashed blue curve is a fit to PL intensity, yielding an α of 1.55. For clarity of display, we multiply XX⁰ by 4 and X⁰ by 0.4