4.2 Device Fabrication
First, the ITO substrates were sequentially cleaned ultrasonically in deionized water, acetone, and isopropanol. The substrates were treated with UV-ozone for 15 min before spin-coating. After that, PEDOT:PSS was spin-coated on the ITO surface at 5000rpm and then annealed at 160 ℃ for 15 min in an ambient atmosphere. These samples were transferred into a glove box under a nitrogen atmosphere immediately. The active layer solution was then spin-coated at 3000 rpm to obtain a film thickness of about 100 nm. The film was then annealed at 100 ℃ for 10 min. Then the cathode buffer layer of PFN-Br (about 5 nm) was spin-coated onto the active layer at 3000 rpm for 30 s. Finally, about 100 nm Al was deposited by thermal evaporation as a cathode under vacuum at a pressure of about 2 * 10-4 Pa.