2.3 Device fabrication

The pre-patterned indium tin oxide (ITO) glass substrates were thoroughly washed three times including deionized water, acetone and isopropyl alcohol, then treated by UV-ozone for 15 min. Next, PEDOT:PSS solution was spin-coated on the substrates at 5500 rpm for 30 s and annealed at 150 °C for 15 min. Then, these substrates were transferred to a N₂-filled glovebox to the next step. Subsequently, the TFB layers were deposited by spin-coating the TFB in chlorobenzene solution (8 mg/ml) at 3000 rpm for 30 s and annealing at 150°C for 30 min. The QD emitting layers were deposited by spin-coating the QD in n-octane solution (18 mg/ml) on the TFB layer at 2000 rpm for 30 s. And after 20 min, the ZnO layer were deposited by spin-coating the ZnO nanoparticle in ethanol solution (40 mg/ml) at 2000 rpm for 30 s and annealing at 60°C, 30 min. Finally, the films were loaded into a vacuum chamber to deposit Al cathode (100 nm, vacuum pressure ≈3 × 10⁻⁷ torr) and encapsulated by UV-curable resin with a cover glass. The effective area of the device is 4.0 mm² by a shadow mask.