To demonstrate the capabilities of the UCNP-SnS2 nanocomposite, we evaluated its use as a photodetector (Figure ). To fabricate a simple proof-of-concept device, we drop-cast Sn2S6 4- -capped UCNPs onto interdigitated ITO electrodes on glass that was obtained commercially (Figure ) and annealed the sample at 350 °C to form the UCNP-SnS2 composite. We hypothesized that the embedded UCNPs would absorb IR light and emit upconverted UV and blue light that could be absorbed by the surrounding SnS2 matrix. The resulting increase in the concentration of charge carriers in the SnS2 semiconductor in principle should lead to an increase in the observed current at a constant applied voltage.