Maskless RGB Color Patterning via Dye Diffusion for Vacuum-Deposited Small Molecule OLED Displays

摘要

A maskless RGB color patterning technique based on dye diffusion is proposed here for vacuum-deposited small molecule OLED displays. This approach utilizes selective diffusion of dyes through thermal diffusion via physical contact for color patterning. The proposed maskless color patterning technique enables us to overcome challenging issues in the conventional color patterning technique using fine metal shadow masks. The maskless color patterning technique based on dye diffusion has been suggested as a color patterning technique for polymer OLEDs. However, it has not yet been applied to vacuum-deposited small molecule OLEDs likely due to several expected concerns such as limited diffusion and contact-induced damage in small molecule films. The purpose of the present study is therefore to test whether the color pattering technique based on dye diffusion can be applied to vacuum-deposited small molecule OLEDs. In order to investigate that, red, green, and blue OLEDs are fabricated side by side on one substrate by doping dyes into host through thermal diffusion via physical contact. Device performance of the fabricated devices, including electroluminescence spectra and IVL characteristics, is tested to investigate if molecular diffusion is sufficient for obtaining desired color spectrum and investigate effects of the physical contact.