title: Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects.
abstract: The synthesis of lanthanide-activated phosphors is pertinent to many emerging applications, ranging from high-resolution luminescence imaging to next-generation volumetric full-color display. In particular, the optical processes governed by the 4f-5d transitions of divalent and trivalent lanthanides have been the key to enabling precisely tuned color emission. The fundamental importance of lanthanide-activated phosphors for the physical and biomedical sciences has led to rapid development of novel synthetic methodologies and relevant tools that allow for probing the dynamics of energy transfer processes. Here, we review recent progress in developing methods for preparing lanthanide-activated phosphors, especially those featuring 4f-5d optical transitions. Particular attention will be devoted to two widely studied dopants, Ce3+and Eu2+. The nature of the 4f-5d transition is examined by combining phenomenological theories with quantum mechanical calculations. An emphasis is placed on the correlation of host crystal structures with the 5d-4f luminescence characteristics of lanthanides, including quantum yield, emission color, decay rate, and thermal quenching behavior. Several parameters, namely Debye temperature and dielectric constant of the host crystal, geometrical structure of coordination polyhedron around the luminescent center, and the accurate energies of 4f and 5d levels, as well as the position of 4f and 5d levels relative to the valence and conduction bands of the hosts, are addressed as basic criteria for high-throughput computational design of lanthanide-activated phosphors.
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Xian
authors.initials: X
authors.lastname: Qin
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Xiaowang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University , Nanjing 211816, P. R. China.|Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts and Telecommunications , Nanjing 210023, P. R. China.
authors.forename: Wei
authors.identifier: http://orcid.org/0000-0001-7004-6408
authors.initials: W
authors.lastname: Huang
authors.affiliation: Luminescent Materials Laboratory, DB, University of Verona , Strada Le Grazie 15, I-37134 Verona, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bettinelli
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore.|Center for Functional Materials, NUS Suzhou Research Institute , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Xiaogang
authors.identifier: http://orcid.org/0000-0003-2517-5790
authors.initials: X
authors.lastname: Liu