When comparing the surface normal and enclosing box results, for device geometries 1, 6, and 7 the results are essentially equivalent. This is because these geometries are virtually rectangular, so adding an enclosing box around them should not change the efficiency. For all other designs, the enclosing box method systematically predicts a lower external photon efficiency. This is likely to be due to the increased distance that the exit rays must travel from the edge of the device to the edge of the enclosing box. Some rays may be angled such that they exit the top or bottom of the box, reducing the simulated efficiency. However, for devices 2-4, since each has a flat edge, in experiment it would be possible to align the flat edge of the device with the input port on the integrating sphere and essentially replicate the surface normal technique,