We fabricated the traditional NIR-to-visible UC devices (see Figure ) by spin coating PbS QDs from toluene on cleaned glass substrates followed by annealing at 70 °C and thermal co-evaporation of approximately 64 nm (optimized for our device stack) of 1 vol% DBP in rubrene on top. For our novel device architecture (Figure ), TCA was spincoated on top of the PbS QD film before annealing and thermal co-evaporation of approximately 64 nm of rubrene/DBP. All UC devices were encapsulated with glass slides using UV-curing epoxy glue to prevent oxygen ingress. These devices were excited using an 808 nm laser to observe UC from rubrene/DBP (550-750 nm emission) through a 750 nm short-pass filter (see UC emission spectrum of rubrene/DBP in Figure ). See the Methods section for further details on the UC photoluminescence measurements.