Efficient oxide phosphors for light upconversion; green emission from Yb³⁺and Ho³⁺co-doped Ln₂BaZnO₅(Ln = Y, Gd)

Abstract

The optical properties of Yb 3+ and Ho 3+ co-doped Y 2 BaZnO 5 , synthesized by solid-state reactions, are investigated in detail. Under 977 nm excitation (~2.5 W/cm 2 ), bright green upconversion emission is observed. Concentration dependence studies at room temperature show that relatively high infrared to visible upconversion efficiencies are obtained with values up to ~2.6%. The results of power dependence studies and temperature dependent lifetime measurements allow us to determine the dominant upconversion mechanisms in Yb 3+ : Ho 3+ co-doped Y 2 BaZnO 5 oxides. The materials presented in this paper constitute new and efficient upconversion phosphors which may find utility in a variety of applications.

Near infrared up-conversion in organic photovoltaic devices using an efficient Yb3+:Ho3+ Co-doped Ln2BaZnO5 (Ln = Y, Gd) phosphor

“…There is no requirement for coherent excitation in achieving UC emission which is dominated by two successive energy transfer steps from Yb 3þ to Ho 3þ . 42 As a result, the full spectral range of the Yb 3þ 2 F 7=2 to 2 F 5=2 absorption shown in Figure 1(c) may be utilized. Therefore, so long as sufficient power density is achieved within this spectral region as discussed above the approach remains valid.…”

“…The exploration of the use of UC phosphor materials is particularly timely following the recent development of a series of rare-earth ion doped materials which include the highest reported ($5.2%) UC efficiencies from the NIR to visible and the rapid developments within this field. [40][41][42][43][44] In this work, we describe the first detailed study that combines the use of these newly available high-efficiency UC phosphors with OPV devices that provide the information required for the further development of this new approach. Upconversion external quantum efficiencies reaching 0.0052% are demonstrated upon 986 nm excitation which could be increased to 0.031% via the use of transparent electrodes matching those achieved in a-Si:H photovoltaic devices.…”

Oxide phosphors for light upconversion; Yb3+ and Tm3+ co-doped Y2BaZnO5

“…This suggests that the Yb 3þ À Tm 3þ interaction dynamics govern the UC temporal behavior under 974 nm excitation, rather than the deexcitation lifetimes of the Tm 3þ multiplets. 25 …”

“…Recently, the upconversion properties of Ln 2 BaZnO 5 : Yb 3þ , Er 3þ and Ln 2 BaZnO 5 : Yb 3þ , Ho 3þ (Ln ¼ Y, Gd) under 980 nm continuous and pulsed excitation were investigated and efficient visible emissions observed in the red and the green. [23][24][25] In the present work, we focus on the investigation of Yb 3þ , Tm 3þ co-doped Y 2 BaZnO 5 materials for infrared to infrared and blue upconversion. Luminescence mechanisms are elucidated through power dependence studies and lifetime measurements on samples with different dopant concentrations.…”

Upconversion luminescence, ferroelectrics and piezoelectrics of Er Doped SrBi4Ti4O15

“…[27][28][29] Oxide materials are usually chemically, mechanically, and thermally stable, and therefore can be promising hosts for light UC applications. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] For these purposes, Er doped many oxide hosts UC materials have been designed and prepared, such as ZnO, 27 43 and NaNbO 3 44 have been studied. However, these types of pervoskite oxides have chemical and physical stability but low emission efficiency due to their low solubility of trivalent rare earth ions.…”