Rare Earth Complexes with 5d-4f Transition: New Emitters in Organic Light-Emitting Diodes

Organic light-emitting diodes (OLEDs) are considered as next-generationdisplays and lighting technologies. During the past three decades, various luminescentmaterials such asfluorescence, phosphorescence, and thermally activated delayedfluorescencematerials have been subsequently investigated as emitters. To date, blue OLEDs are still thebottleneck as compared to red and green ones because of the lack of efficient emitters withsimultaneous high exciton utilization efficiency and long-term stability. Recently, d-ftransition rare earth complexes have been reported as new emitters in OLEDs with potentialhigh efficiency and stability. In this Perspective, we present a brief introduction to OLEDs andan overview of the previous electroluminescence study on d-f transition rare earth complexes.This is followed by our recent developments in cerium(III) complex- and europium(II)complex-based OLEDs. Wefinally discuss the challenges and opportunities for OLED studybased on d-f transition rare earth complexes

Automated summary

Organic light-emitting diodes (OLEDs) are regarded as the next-generation display and lighting technologies. Blue OLEDs, however, face challenges due to the lack of efficient emitters with high exciton utilization efficiency and long-term stability. Recently, d-f transition rare earth complexes have emerged as potential emitters for OLEDs with high efficiency and stability. This Perspective provides an introduction to OLEDs, an overview of previous electroluminescence research on d-f transition rare earth complexes, and discusses recent developments in cerium(III) complex- and europium(II)complex-based OLEDs.