title: A core-multiple shell nanostructure enabling concurrent upconversion and quantum cutting for photon management.
abstract: Photon management enables the manipulation of the number of input photons by conversion of two or more light quanta into one (upconversion) or vice versa (quantum cutting). Simultaneous realization of both these processes in a single unit provides unique opportunities of efficient utilization of photons throughout a broad spectral range. Yet, concurrent realization of these two parallel optical processes in one single unit remains elusive, limiting its impact on many existing or possible future applications such as for panchromatic photovoltaics. Here, we describe an epitaxial active core/inert shell/active shell/inert shell fluoride nanostructure to implement upconversion and quantum cutting within spatially confined and isolated rare-earth-doped active domains. The core area transforms infrared photons through trivalent erbium (Er3+) ions into three- and two-photon upconverted visible and near infrared luminescence, while the second shell domain splits an excitation photon into two near infrared photons through cooperative quantum cutting from one trivalent terbium ion (Tb3+) to two trivalent ytterbium ions (Yb3+). The inert layer in between the active domains is able to effectively suppress the destructive interference between upconversion and quantum cutting, while the outermost inert shell is able to eliminate surface-related quenching. This design enables the colloidal core/multishell nanoparticles to have an upconversion quantum yield of ∼1.6%, and to have a luminescence yield of the quantum cutting process as high as ∼130%. This work constitutes a solid step for flexible photon management in a single nanostructure, and has an implication for photonic applications beyond photovoltaics.
authors.affiliation: MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-systems and Micro-structures, Ministry of Education, Harbin Institute of Technology, Harbin, Heilongjiang 150001, People's Republic of China. chenguanying@hit.edu.cn and Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA. pnprasad@buffalo.edu.
authors.forename: Wei
authors.initials: W
authors.lastname: Shao
authors.affiliation: MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-systems and Micro-structures, Ministry of Education, Harbin Institute of Technology, Harbin, Heilongjiang 150001, People's Republic of China. chenguanying@hit.edu.cn and Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA. pnprasad@buffalo.edu.
authors.forename: Guanying
authors.identifier: http://orcid.org/0000-0002-4789-1176
authors.initials: G
authors.lastname: Chen
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA. pnprasad@buffalo.edu.
authors.forename: Tymish Y
authors.identifier: http://orcid.org/0000-0002-7051-6534
authors.initials: TY
authors.lastname: Ohulchanskyy
authors.affiliation: MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering & Key Laboratory of Micro-systems and Micro-structures, Ministry of Education, Harbin Institute of Technology, Harbin, Heilongjiang 150001, People's Republic of China. chenguanying@hit.edu.cn.
authors.forename: Chunhui
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Theoretical Chemistry & Biology, Royal Institute of Technology, S-10691 Stockholm, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Ågren
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA. pnprasad@buffalo.edu.
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad