Figure 1 plots the number of photon recycling events per initial excitation versus photoluminescence quantum efficiency and escape probability, calculated from equation 6 given in manuscript.

Figures 2 and 3 model photon recycling in methylammonium lead iodide solar cells.

Figure 2 shows the number of photon recycling at maximum power point events versus; thickness (with no charge trapping); charge trapping rate (for a 500nm film); and as a fucntion of front transmission and back reflection coefficients (for a 500nm film). The inset in Figure 2a shows corresponding information to 2a, but at open circuit.

Figure 3 shows number of photon recycling events versus efficiency, both as a function of charge trapping rate for a 500nm film, for a film which interacts with a 2*pi hemisphere and 2.5 degrees solid angle about the sun in a) and c) respectively. b) shows the current-voltage curves for some situations described in a) (for no charge trapping, 500nm film).

Figure 4 models photon recycling in caesium lead bromide light emittiong diodes.

Figure 4: a shows the number of photon recycling events versus thickness (with no charge trapping); b shows the number of photon recycling events versus voltage for different charge trapping rates (for a 100nm film); c the number of photon recycling events versus front transmission and back reflection coefficients (for a 100nm thick film and no charge trapping). Figure 4d presents normalised photoluminescence for three absorption models considered; and e and f the number of photon recycling events versus emitted light (luminous emittance or luminance respectively) both as a function of voltage, for three different emittance models considered, for emission into a 2*pi hemisphere (e) or 2.5 degree solid angle (f), both for a 100nm thin film.