Sn2S6 4-complexes have been previously shown to transform into a semiconducting SnS2 matrix upon annealing at relatively modest temperatures (<200 °C). This property has led to the exploration of Sn2S6 4-as a promising ligand for integrating colloidal nanomaterials in electronic or optoelectronic devices. For instance, annealing Sn2S6 4--capped QDs resulted in a QD-SnS2 composite that had high charge carrier mobilities and could be used as the active component in transistors. Here, we explore the fabrication of a UCNP-SnS2 nanocomposite and evaluate its potential as an upconversion-based photodetector.