The sample was prepared by coating the layers through spin
coater. First, the TiO2 layer was coated at 2500 rpm for 30 s, then
P3HT/PCBM at 3000 rpm for 30 s, and PEDOT at 5000 rpm for 30 s
Fig. 11 shows the morphology of layers. The outer layer is of PEDOT,
the inner is of P3HT:PCBM, and the innermost is TiO2.