Donor Centers Involved into the Quantum Cutting in Ytterbium-Doped Scheelite-Like Crystals
Year: 2020
Authors: Subbotin K.A., Titov A.I., Lis D.A., Sani E., Smirnov V.A., Alimov O.K., Zharikov E.V., Shcherbakov I.A.
Autors Affiliation: Russian Acad Sci, Laser Mat & Technol Res Ctr, Prokhorov Gen Phys Inst, Vavilova Str 38, Moscow 119991, Russia; Mendeleev Univ Chem Technol Russia, Dept Chem & Technol Crystals, Miusskaya Sq 9, Moscow 125048, Russia; CNR INO Natl Inst Appl Opt, Largo E Fermi 6, I-50125 Florence, Italy.
Abstract: Yb-doped Scheelite-like molybdate and tungstate single crystals are promising quantum-cutting materials. The cooperative downconversion from donor centers to Yb ions occurs in heavily Yb-doped crystals of this family. This phenomenon can substantially raise the efficiency of crystalline silicon photovoltaic cells. However, the nature of donor centers is still unknown. Herein, several versions of this nature are tested and discussed: Yb3+ ion (its high-energy charge transfer states); Yb2+ ion; self-trapped exciton at molybdate/tungstate complex; color centers based on oxygen vacancies; accidental impurities. To test these assumptions, a series of Scheelite-like molybdate and tungstate single crystals (CaMoO4, CaWO4, NaLa(MoO4)(2), NaGd(MoO4)(2), NaGd(WO4)(2), and NaY1-xGdx(WO4)(2)) are grown, both undoped and doped with different Yb-concentrations. The complex spectroscopic investigations of these crystals are performed. As a result of the studies, three versions, self-trapped excitons at [MoO4]/[WO4] complexes, color centers at oxygen vacancies, and accidental impurities, coming into the crystals with MoO3, are rejected. The applicability of the other versions should be refined.
Journal/Review: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
Volume: 217 (4) Pages from: 1900659-1 to: 1900659-8
More Information: This work was supported by Russian Fund for Basic Research (grant no. 17-02-01245), and by the Presidium of RAS (Program I.7 Modern problems of photonics, the probing of inhomogeneous media and materials).KeyWords: quantum cutting; Scheelites; ytterbiumDOI: 10.1002/pssa.201900659