Abnormal thermally enhanced upconversion luminescence of lanthanide-doped phosphors: proposed mechanisms and potential applications

Luminescent materials usually suffer from luminescence thermal quenching because of the aggravation of various nonradiation relaxations with elevated temperatures. However, recent discovery on the abnormal thermally enhanced upconversion luminescence has triggered extensive attention. Although considerable efforts have been spent exploring the underlying mechanism, significant disagreements remain for different proposed mechanisms. In this mini-review, we have briefly summarized recent progress on abnormal thermally enhanced upconversion luminescence for lanthanide-doped phosphors, focusing mainly on the various mechanisms proposed so far. The potential applications in various areas that such unique luminescence behavior could bring are also introduced. Recent progress on the abnormal thermally enhanced upconversion luminescence, in terms of phenomena, various mechanisms and potential applications, is reviewed.