ITO-free down-conversion white organic light-emitting diodes with structured color conversion layers for enhanced optical efficiency and color rendering

► Down-conversion white organic light-emitting diodes (WOLEDs) adopting cavity-enhanced ITO-free blue OLEDs are fabricated. ► Microlens-array shape color conversion layer (CCL) assists outcoupling of down-converted photons confined in substrate mode. ► Microcavity blue OLEDs and structured CCLs enable WOLEDs with high efficiency and excellent color rendering capability. ► Being ITO-free, the proposed WOLEDs exhibit supreme flexibility when built on a plastic substrate.