White light upconversion through precise manipulation of energy transfer channels in a core-shell-shell nanostructure

Abstract

Photon upconversion of lanthanides is an important approach for white light emission, showing great potential in displays, nanophosphors, white light lasers and so on. However, the white light upconversion in previous reports is usually based on the codoping schemes with conventional lanthanide emitters such as Er3+/Tm3+ or Ho3+/Tm3+, of which the performance is limited by the serious quenchable interactions between dopants (e.g., cross relaxation). Here, we report a new mechanistic approach to the white light upconversion by constructing the LiYbF4:Tb@LiGdF4:Yb/Tm@LiYF4:Eu core-shell-shell nanostructure. The use of lithium lanthanide fluoride matrix can improve the doping content of Yb3+ into the host lattice easily with resultant enhancement in the absorption of the excitation energy and subsequent upconversion luminescence. Through combining both interfacial energy transfer (IET) and cooperative sensitization upconversion (CSU), the white light upconverting emission has been realized under 980 nm excitation. Also, the upconversion emission has different lifetime values providing a temporal way to manipulate the upconversion emission colors. Our results offer a new experimental strategy for white light upconversion of lanthanide-doped materials, showing great promise in applications such as anti-counterfeiting.