A mixed solution of P3HT:PC6oBM was prepared by adding 1 ml of chlorobenzene to 15 mg of P3HT and 15 mg of
PC6oBM, and then spin-coated at 700 rpm for 1 min and annealed at 150°C for 10 min in a N2 glove box as the active
layer. Finally, layers of 0.6 nm thick LiF and 100 nm thick Al was thermally evaporated on top of the active layer
through a shadow mask as the cathode. The current-voltage characteristics of the encapsulated devices were measured in
air under illumination with 100mW/cm2 simulated solar light. The film thickness and the surface profile were
characterized by a KLA-Tencor D-120 profiler. The sheet resistance was measured using a four-point probe system. The
UV -vis transmission spectra were measured using a UV -Vis spectroscopy (MAPADA UV -3100).