Highly efficient near-infrared to visible up-conversion process in

Synthesis of β-Phase NaYF4:Yb,Er Upconversion Nanocrystals and Nanorods by Hot-Injection of Small Particles of the α-Phase

“…During the last years, a large number of research papers was pub-lished on the synthesis of NaREF 4 nanocrystals (RE = rare-earth), since NaREF 4 and LiREF 4 are attractive host lattices for a variety of functional optical materials such as upconversion phosphors, [6][7][8][9][10][11][12][13][14] quantum-cutting phosphors, [15][16][17][18][19] laser materials, [20,21] and materials for solar cell applications [22][23][24][25][26]. A variety of synthetic methods has been described for producing solvent-dispersible sodium rare-earth tetrafluoride nanocrystals with controlled size, shape and capping ligand, including thermal decomposition, [7,[27][28][29][30][31][32] co-precipitation, [6,11,[33][34][35][36][37][38][39][40] or solvothermal methods [41][42][43][44][45][46][47]…”

Solar Spectrum Conversion for Photovoltaics Using Nanoparticles

“…In addition, the emission spectrum of Dysprosium is similar to that of Erbium, but the content of Dy 3+ should be <0.1%, to avoid quenching (Auzel 2004, Strümpel et al 2007). NaYF 4 co-doped with (Er 3+ , Yb 3+ ) is to date the most efficient upconverter (Suyver et al 2005a, Suyver et al 2005b, with ~50% of all absorbed NIR photons up converted and emitted in the visible wavelength range. However, the (Yb, Er) couple is not considered beneficial for up conversion in c-Si cells, as silicon also absorbs in the 920-980 nm wavelength range.…”

Investigation of the Up-conversion Properties of Er-Yb-doped Calcium Tantalates with Various Ca/Ta Ratios

“…UC emissions have been observed for a wide variety of host materials such as fluorides, chlorides, bromides, and oxides [7][8][9][10][11][12][13]. Fluorides are commonly studied owing to their low phonon energy and low energy loss resulting from non-radiative relaxation.…”