| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1263997 | Organic Electronics | 2012 | 8 Pages |
A simple and cost-effective approach is proposed as an alternative to conventional oxygen plasma treatment to modify surface property of Indium tin oxide (ITO) anode of a fluorescent organic light-emitting diode (OLED). This was achieved by treating the ITO anode in supercritical CO2 (SCCO2) fluids with hydrogen peroxide (H2O2). The SCCO2/H2O2 treatment yielded an ITO work function of 5.35 eV after 15 min treatment at 85 °C and 4000 psi, which was significant higher than 4.8 eV of the as-cleaned ITO surface and was slightly less than 5.5 eV of the ITO surface treated by oxygen plasma. The highest work function achieved was 5.55 eV after 45 min SCCO2/H2O2 treatment. The SCCO2/H2O2 treatment can be used to tailor the ITO work function through changing the operation pressure of the treatment. In addition, the correlated dependence of OLED performance on the ITO anodes with and without the treatments was investigated. The maximum power efficiency of 1.94 lm/W was obtained at 17.3 mA/cm2 for the device with 15 min SCCO2/H2O2 treatment at 4000 psi. This power efficiency was 19.3% and 33.8% higher than those of the oxygen plasma treatment and as-clean, respectively. The improvement in device efficiency by the SCCO2/H2O2 treatments can be attributed to enhanced hole injection and balance in charge carriers due to increased work function and surface energy of the ITO anodes.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► SCCO2 treatment is proposed to modify surface property of ITO anode of an OLED. ► ITO work function was tailored by changing operation pressure of SCCO2 treatment. ► SCCO2 treatment removed contaminants and increased oxygen content of ITO surface. ► Highest work function achieved was 5.55 eV after 45 min SCCO2 treatment at 4000 psi. ► Power efficiency of SCCO2-treated OLED is 19.3% higher than O2-plasma treated device.
