We show that the Sn2S6 4-ligands can be transformed into a SnS2 matrix upon annealing at 350 °C, forming a UCNP-SnS2 nanocomposite. Finally, we fabricate a proof-of-concept UV and NIR photodetector using the solution-deposited UCNP-SnS2 nanocomposite. These findings reveal a potential pathway for using inorganic ligands to enhance the properties and applications of UCNPs.