Multicolor organic LEDs processed by integration of screen printing and thermal transfer printing

摘要

Color integration in organic LEDs (OLEDs) on a substrate has always been a challenge due to the incompatibility of OlED materials with the conventional photolithography. In this paper, we report a process for the fabrication of large-area multicolor OLEDs of arbitrary patterns by combination of thermal-transfer printing and screen-printing. Thermal transfer printing is used to introduce color-tuning dyes into a thermally stable OLED polymer layer from a dye-dispersed polymer layer on the donor plate. Such a process permits controllable and uniform doping of a polymer layer over large areas. By using a patterned color donor plate, color integration in OLEDs could be accomplished with a single thermal transfer step. In this work, the source plate containing multicolor patterns is fabricated by screen-printing. The RGB color patterns were printed sequentially by using RGB inks prepared by dispersing nile red, C6 and perylene into a commercial screen-printing paste. Based on these printing approaches, we have successfully fabricated multicolor single-layer and heterostructure OLEDs.