A study on thin film uniformity in a roll-to-roll thermal evaporation system for flexible OLED applications

A roll-to-roll (R2R) thermal evaporation system was developed to manufacture low-cost flexible OLEDs. A vacuum-compatible bottom-up thermal evaporation method was adopted to ensure the quality and the stability of the thin film. DSMC (Direct Simulation Monte Carlo) simulation was used to predict the CD (Cross Direction) uniformity of the thickness of the deposited thin film. And, a uniformity-compensation method using the Z-map algorithm was developed to realize entire uniformity on a continuous roll-to-roll scan-type substrate. An experimental investigation confirms that these simulations fit the actual test results well. And, a flexible OLED lighting sample could be fabricated using the proposed method and the developed R2R equipment. These results represent a meaningful step towards the production of low-cost flexible OLED applications.