From the TA data, we can identify an initial spectrum (100 fs -1 ps) with a positive peak corresponding to the A-exciton GSB at 616 nm (Fig. and S14) and another peak from the Bexciton GSB at 520 nm. Over the first 10 ps, these features disappear and a broad positive feature between 600-650 nm arises with a sharp negative peak overlapping at 620 nm. The dynamics of the spectral components are extracted using spectra at early (150 fs) and long (1.7 ns) times, as detailed in Supplementary Note 6. The initial component exhibits an average lifetime of 1-5 ps across two independent samples, with the emergence of a broad feature occurring concurrently. The broad feature is similar to that observed in liquid-exfoliated WS2 in our previous work. We previously assigned this broad feature to the GSB of multilayer WS2 arising due to energy transfer. However, as the prepared mechanically exfoliated samples here do not have any multilayer parts (Fig ) this feature must be associated with something else. We assign this to the GSB of a charged sulfur vacancy trap state which is supported by our DFT simulation as we discuss subsequently.