We proceed to analyze the transient dynamics of Ru-MoS 2 monolayer. In comparison to the pristine MoS 2 , a negative transient signal emerges at an early time, still indicative of the ground state bleach and stimulated emission signal contributions. However, the lack of the positive signal after 10 ps implies negligible excited state absorption signal, indicating no trion formation, which agrees with the suppression of PL signals from trions (Figure ). The band alignment of the heterojunction suggests that a hole transfer from the valence band of MoS 2 to the HOMO of Ru(DPPZ) 2 L-Pro is energetically favorable, eliminating the trion population.