To measure the EQEs, the method introduced by Izawa et al. was used. The photoluminescence set up described above was used for this measurement. A rubrene/DBP-only film (~64 nm) was used as the standard with a known PLQY (measured in the integrating sphere as described above). The PL (integrated 500-700 nm) from rubrene/DBP-only samples (Istd) was measured using a 447 nm continuous wave laser. With the same optical alignment, the UCPL (integrated 500-700 nm) from upconversion devices (IUC) was measured using an 808 nm continuous wave laser with an intensity of 5.3 W/cm 2 . The incident power of the 447 nm (Pstd) and 808 nm (PUC) lasers were measured using a Thorlabs power meter (PM100D meter with S120VC sensor). All measurements were performed with a 750 nm short pass filter (Thorlabs). For each device stack, triplicates were fabricated and 4 points on each sample were measured with random positions. The resulting averages and standard deviations were propagated using the Python uncertainties package. Equation was used to calculate the EQEs of the different devices.