title: Enhanced Quantum Cutting via Li+Doping from a Bi3+/Yb3+-Codoped Gadolinium Tungstate Phosphor.
abstract: The Bi3+/Yb3+-codoped gadolinium tungstate phosphor has been synthesized through a solid-state reaction method. The structural characterization reveals the crystalline nature of the phosphor. The Bi3+-doped phosphor emits visible radiation from the blue to red regions upon excitation with 330 and 355 nm. The addition of Yb3+to the Bi3+-doped phosphor reduces the emission intensity in the visible region and emits an intense near-infrared (NIR) photon centered at 976 nm through a quantum-cutting (QC) phenomenon. This is due to cooperative energy transfer (CET) from the3P1level of Bi3+to the2F5/2level of Yb3+. The presence of Li+ions in the Bi3+/Yb3+-codoped phosphor enhances the emission intensity in the NIR region up to by 3 times, whereas the emission intensity in the visible region is significantly reduced. The energy transfer (ET) from the Bi3+ions to the Yb3+ions is confirmed by lifetime measurements, and the lifetime for the3P1level of Bi3+decreases continuously with increasing Yb3+concentration. The ET efficiency (ηETE) and corresponding QC efficiency (ηQE) are calculated and found to be 29% and 129%, respectively. The presence of Li+enhances the QC efficiency of the phosphor up to 43%. Thus, the Bi3+/Yb3+/Li+-codoped phosphor is a promising candidate to enhance the efficiency of a crystalline-silicon-based solar cell through spectral conversion.
authors.affiliation: Department of Physics, Institute of Science, Banaras Hindu University , Varanasi 221005, India.
authors.forename: Ran Vijay
authors.initials: RV
authors.lastname: Yadav
authors.affiliation: Department of Physics, Institute of Science, Banaras Hindu University , Varanasi 221005, India.
authors.forename: Ram Sagar
authors.initials: RS
authors.lastname: Yadav
authors.affiliation: Department of Physics, Institute of Science, Banaras Hindu University , Varanasi 221005, India.
authors.forename: Amresh
authors.initials: A
authors.lastname: Bahadur
authors.affiliation: School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University) , Varanasi 221005, India.
authors.forename: Akhilesh Kumar
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Department of Physics, Institute of Science, Banaras Hindu University , Varanasi 221005, India.
authors.forename: Shyam Bahadur
authors.initials: SB
authors.lastname: Rai