Towards broad range and highly efficient down-conversion of solar spectrum by Er3+–Yb3+ co-doped nano-structured glass-ceramics

Transparent oxyfluoride glass ceramics

“…An EDX study unequivocally confirmed that nanocrystals formed in the 32SiO 2 -9AlO 1.5 -31.5CdF 2 -18.5PbF 2 -5.5ZnF 2 :3.5ErF 3 system were, in fact, cubic PbF 2 :RF 3 solid solutions [132]. Therefore, practically all later publications [115,120,126,117,130,131] considered cubic PbF 2 :RF 3 nanocrystals as the crystalline phase of the aforementioned system.…”

“…For DC mechanism, one UV-blue solar photon (300-500 nm) dissipating as heat in the solar cell (socalled carrier thermalization) can be absorbed by the donor ions, i.e., Tb 3+ , Pr 3+ , Nd 3+ , Tm 3+ , Ho 3+ , Er 3+ or Tm 3+ and then simultaneously converted into two Yb 3+ NIR photons above the c-Si energy gap [105,130,149,356]. On the other hand, the NIR-QC system also may be implemented in R 3+ (R = Dy, Er, Ho and Tm) singly doped luminophores [355].…”

Up- and down-conversion emissions from Er3+ doped K2YF5 and K2YbF5 crystals

“…This effect is particularly evident under 520 nm excitation when the intensity of the near-IR emission is enhanced with respect to the red one. This broad near-IR band can be attributed to the emission on the 2 F 5/ 2 -2 F 7/2 transition of Yb 3 þ ions excited through the downconversion (DC) process [8,12]. DC for the Er 3 þ -Yb 3 þ couple includes several CR processes, which can be also phonon-assisted [8,11,12], resulting in deexcitation of the Er 3 þ ion and simultaneous excitation of adjacent Yb 3 þ ions emitting at $ 1 μm, Fig.…”

“…The potential applications of Er-doped phosphors are in the field of solid-state lighting [3], biological labeling [4,5] or enhancement of the solar-cell efficiency [6] as well as the data concerning Er 3 þ up-conversion visible lasers have been reported [7]. Down-conversion (that is frequently called quantum cutting) is a process when one high-energy photon (UV/visible) is cut into two lower energy photons (near-IR) [8]. This process can be very efficient for Yb 3 þ -RE 3 þ ions pairs (where RE stands for Tb, Pr, Tm, Er, Nd or Ho ions) [9,10].…”

“…Typically, absorption of UV/visible light by RE 3 þ ions leads to the emission of Yb 3 þ ions at $ 1 μm corresponding to the 2 F 5/2 -2 F 7/2 transition. Down-conversion is Er 3 þ and Er 3 þ /Yb 3 þ doped fluoride and oxyfluoride materials (in the form of single crystals, glass-ceramics or nanopowders) provide intense up-and down-conversion luminescence [1][2][3][4][5][6][7][8].…”