Construction of NaYF4:Yb,Er(Tm)@CDs composites for enhancing red and NIR upconversion emission

Abstract

A simple sol–gel method was used to integrate carbon dots (CDs) with upconversion (UC) luminescent materials NaYF₄:Yb,Er(Tm) to form composites. We found for the first time that the CDs acted as a sub-energy level to mediate energy transfer between different levels of the rare earth ions. Impressively, enhanced red and NIR upconversion emissions were achieved in the NaYF₄:Yb,Er(Tm)@CDs composites.