4.6. Fabrication and Characterization of PLEDs

All PLED devices were prepared and characterized following the process as follows. The ITO substrates were cleaned in an ultrasonic bath with detergent, acetone, isopropanol, and deionized water, dried in an oven at 120°C for 2 hours, and treated with ultraviolet ozone for 10 min before spin-coating. Firstly, a 40 nm thick PEDOT: PSS was spin-coated and then annealed at 120°C for 20 minutes. Then, the emitting layer was spin-coated from CB solution (10 mg/mL) and annealed at 120°C for 15 minutes in nitrogen-filled glovebox. Finally, the residue layers, such as 20 nm TPBi, 0.8 nm LiF, and 100 nm Al, were deposited by thermal evaporating at a pressure below 1 × 10⁻⁵ mbar. The J − L − V curves were recorded using a combination of a Keithley source meter (model 2602) and a luminance meter. The EL spectra of the devices were measured using a PR-655 spectrophotometer. All the measurements were taken in the ambient condition at room temperature.