Zirconia based Ho³⁺–Yb³⁺ codoped upconverting nanophosphors for green light emitting devices applications

Abstract

Photoluminescence study of the Ho-Yb codoped ZrO, AlZrO and YZrO nanophosphors, synthesized by chemical co-precipitation method, upon excitation at 450 and 980 nm radiations have been performed. An improvement of about ∼4.5 times in the downconversion emission intensity of green band corresponding to the F, S → I transition for codoped YZrO nanophosphors compared to ZrO codoped nanophosphors has been observed. On varying the pump power density upon 980 nm excitation the colour tunability in the codoped YZrO nanophosphors has been observed. UC emission intensity of the green band arising from the Ho ion in the codoped YZrO nanophosphors is enhanced about ∼22 times compared to that of the codoped ZrO nanophosphors. The absorption and UC emission study for the codoped YZrO nanophosphors dispersed in different biologically compatible solvents viz. water, methanol, ethanol and dimethyl sulfoxide (DMSO) has been performed. The green UC emission intensity of about ∼1.3 and ∼1.7 times for the efficient codoped YZrO nanophosphors dispersed in methanol compared to that dispersed in water and DMSO respectively has been observed. The absorption spectra of an efficient upconverting YZrO nanophosphors dispersed in methanol exhibit no change with the passage of time.

Photon avalanche assisted upconversionviacustomizing the green emission

“…The observation shows that from single Ho 3+ doped to Ho 3+ /Yb 3+ /Mn 4+ codoped phosphors, the CCT value shifted from cool light to warm light region. 69 Thus, the present phosphors can be used in green and broad visible upconverters.…”

Fluorescence intensity ratio technique and its reliability

“…Furthermore, the pump power dependent CIE coordinates establishes the non-tunability of the green colour emitted by the codoped glasses. The colour purity of the codoped sample has been calculated from the expression [54],…”