Review on the Electroluminescence Study of Lanthanide Complexes

Thanks to their characteristic photophysical properties, lanthanide complexes are of great value in many fields. Especially, high‐purity green and red lights from Tb(III) and Eu(III) complexes are particularly suitable for displays, and near‐infrared (NIR) emissions from Nd(III), Er(III), and Yb(III) complexes have huge potential in night‐vision devices. Therefore, since shortly after the birth of organic light‐emitting diodes (OLEDs), electroluminescence studies on lanthanide complexes have attracted much attention. This review comprehensively summarizes advances in the electroluminescence study of all lanthanide complexes in the past 30 years, where the lanthanide complexes are basically classified according to their emission wavelengths, i.e., visible light, near‐infrared (NIR) light, and simultaneous visible and NIR light. On this basis, the challenges and opportunities faced by electroluminescence of lanthanide complexes are also discussed. Due to the high color purity and high theoretical efficiency, lanthanide complexes are valuable for electroluminescence applications. This review summarizes significant progress over the last three decades in this field. The mechanisms and the strategies for improving device efficiency as well as the challenges and opportunities of lanthanide complexes in the electroluminescence field are discussed.