Dry dye printing and solvent-enhanced dye diffusion were used to locally dope a previously spin-coated poly(9-vinylcarbazole) (PVK) polymer film with different dyes to fabricate side-by-side red, green, and blue (RGB) organic light-emitting device pixels. The fabrication details and the resolution and stability of this patterning technique are discussed. The technique was then used to make combined polymer/ small-molecule devices, in which the printability of polymer for color integration was combined with the superior transport properties and thin-layer capabilities of small molecules for high efficiency and low leakage current. To reduce reverse leakage current and raise efficiency, a blanket tris-8-hydroxyquinoline aluminum (Alq3) electron transport layer was deposited on top of the polymer layer after the dye diffusion step, along with a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline hole/exciton blocking layer between the Alq3 and the PVK to ensure that all light emission occurred from the doped polymer and not from the Alq3. Devices with this hybrid doped polymer/small molecule structure have an extremely low reverse leakage current (with a rectification ratio of 106 at ±10 V). The electroluminescence efficiency of the devices was optimized by varying the dye concentration of the printing plate. A three-color passive-matrix test array with 300 μm × 1 mm RGB subpixels was demonstrated with this structure.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering
- Flat-panel displays
- Full color
- Organic light-emitting diode (OLED) integration
- Passive matrix