Broadband Ce(III)-Sensitized Quantum Cutting in Core-Shell Nanoparticles: Mechanistic Investigation and Photovoltaic Application.

Quantum cutting in lanthanide-doped luminescent materials is promising for applications such as solar cells, mercury-free lamps, and plasma panel displays because of the ability to emit multiple photons for each absorbed higher-energy photon. Herein, a broadband Ce3+-sensitized quantum cutting process in Nd3+ ions is reported though gadolinium sublattice-mediated energy migration in a NaGdF4:Ce@NaGdF4:Nd@NaYF4 nanostructure. The Nd3+ ions show downconversion of one ultraviolet photon through two successive energy transitions, resulting in one visible photon and one near-infrared (NIR) photon. A class of NaGdF4:Ce@NaGdF4:Nd/Yb@NaYF4 nanoparticles is further developed to expand the spectrum of quantum cutting in the NIR. When the quantum cutting nanoparticles are incorporated into a hybrid crystalline silicon (c-Si) solar cell, a 1.2-fold increase in short-circuit current and a 1.4-fold increase in power conversion efficiency is demonstrated under short-wavelength ultraviolet irradiation. These insights should enhance our ability to control and utilize spectral downconversion with lanthanide ions.

Silver europium(III) polyphosphate.

Europium(III) silver polyphosphate, AgEu(PO(3))(4), was prepared by the flux method. The atomic arrangement is built up by infinite (PO(3))(n) chains (periodicity of 4) extending along the c axis. These chains are joined to each other by EuO(8) dodeca-hedra. The Ag(+) cations are located in the voids of this arrangement and are surrounded by five oxygen atoms in a distorted [4+1] coordination.

Eu2+ and Mn2+ codoped Ba2Mg(BO3)2--new red phosphor for white LEDs.

A new red phosphor, Ba(2)Mg(BO(3))(2):Eu,Mn, was synthesized by the solid-state reaction method and its photoluminescence properties were investigated by excitation and emission spectra and decay curves. Its excitation band is extending from 250-450 nm, which is adaptable to the emission band of near-ultraviolet LED chips (350-420 nm). Upon the excitation of 365 nm light, the phosphor exhibits strong red emission centered at 615 nm. The relationship between Eu(2+) and Mn(2+) dopants was studied from the viewpoint of a crystal structure and by photoluminescence spectra and decay curves. The results show that the characteristic Eu(2+) emission predominate in the emission band and Mn(2+) promote the redistribution of Eu(2+) at the cation sites of the host crystal.