title: Transition Metal-Involved Photon Upconversion.
abstract: Upconversion (UC) luminescence of lanthanide ions (Ln3+) has been extensively investigated for several decades and is a constant research hotspot owing to its fundamental significance and widespread applications. In contrast to the multiple and fixed UC emissions of Ln3+, transition metal (TM) ions, e.g., Mn2+, usually possess a single broadband emission due to its 3d5electronic configuration. Wavelength-tuneable single UC emission can be achieved in some TM ion-activated systems ascribed to the susceptibility ofdelectrons to the chemical environment, which is appealing in molecular sensing and lighting. Moreover, the UC emissions of Ln3+can be modulated by TM ions (specificallyd-block element ions with unfilleddorbitals), which benefits from the specific metastable energy levels of Ln3+owing to the well-shielded 4felectrons and tuneable energy levels of the TM ions. The electric versatility ofd0ion-containing hosts (d0normally viewed as charged anion groups, such as MoO66-and TiO44-) may also have a strong influence on the electric dipole transition of Ln3+, resulting in multifunctional properties of modulated UC emission and electrical behaviour, such as ferroelectricity and oxide-ion conductivity. This review focuses on recent advances in the room temperature (RT) UC of TM ions, the UC of Ln3+tuned by TM ord0ions, and the UC ofd0ion-centred groups, as well as their potential applications in bioimaging, solar cells and multifunctional devices.
authors.affiliation: State Key Lab of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques South China University of Technology Guangzhou 510641 China.
authors.forename: Shi
authors.initials: S
authors.lastname: Ye
authors.affiliation: State Key Lab of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques South China University of Technology Guangzhou 510641 China.
authors.forename: En-Hai
authors.initials: EH
authors.lastname: Song
authors.affiliation: State Key Lab of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques South China University of Technology Guangzhou 510641 China.
authors.forename: Qin-Yuan
authors.initials: QY
authors.lastname: Zhang
keywords: lanthanide ions; multifunctional materials; transition metal ions; tunable; upconversion