Electromagnetic simulation and multiple light extraction concepts for solution-processed organic light-emitting diodes were explored in this report. Based on the optical simulation results, the device architecture was optimized for maximization of the light out-coupling efficiency. By utilizing a high refractive index substrate, a high light scattering electrode, and an external light extraction structure, trapped photons in the wave-guided and substrate modes were extracted effectively. The best solution-processed device exhibited a maximum external quantum efficiency of 42.9%, a current efficiency as high as 150.1 cd/A, and a power efficacy up to 125.1 lm/W. (C) 2014 Elsevier Ltd. All rights reserved.