Black card was placed below the LSC, and black tape was used on edges not being measured to minimize back-and side-scattering events. The distance of the solar simulator above the sample was calibrated such that 1 sun (1000 ± 10 W/m 2 ) illumination on the top surface of the LSC was attained. The emission spectrum from the single edge of the LSC was collected by a calibrated spectrometer (SpectriLight ILT 950), which was connected to the integrating sphere via a fiber optic cable. This process was repeated for each edge of the LSC. Conversion of the measured spectra to number of emitted photons (through integration), followed by summation of all measured edges, yields the required total photon output (cf. number of output rays in Eq. 1).