Organic light-emitting diodes with split recombination zones: A concept for versatile color tuning

摘要

White organic light emitting diodes (WOLEDs) for general lighting applications are still mostly considered as a possibility rather than a definitive next step in solid-state lighting technology. Vacuum deposited WOLEDs usually run into troubles of complicated manufacturing processes, incompatible emitters, high-precision requirements for emitting layer structuring and monolithic integration. In this work, we present a simple method of achieving white emission from a single-stack OLED with three (red, green and blue) emitters utilizing a laterally structured shadow mask. Only the green emitter is deposited via this mask without any alignment requirements, allowing the decoupling of recombination zones for achieving simultaneous emission from all emitters, circumventing the need of additional charge generating layers or vacuum-breaking structuring steps. A highly tunable white emission is demonstrated, irrespective of charge transporting systems or green emitters used. The resulting WOLEDs show external quantum efficiencies and luminous efficacies up to 14% and 26 lm/W, respectively, with CIE coordinates of (0.40, 0.40) and CRI values of up to 80.