Host‐Sensitized Continuum‐Broad‐Band White‐Light Emitting Yb2O3:Er3+ Phosphor under CW‐NIR Light Absorption

Abstract

AbstractSingle cubic phase Yb2O3:Er3+ phosphors have been synthesized via solid state reaction technique and characterized by X‐ray diffraction (XRD) and Field emission scanning electron microscopy (FE‐SEM) analysis. An unusual continuum broad band white colour upconversion (UC) emission has been observed under 980 nm continuous wave (CW) near infrared (NIR) laser diode excitation. Interestingly, the phosphor shows characteristic erbium ion transitions at low pump power, but at high pump power heat associated continuum broad band emission was realized. The continuum broad band emission was explained on the basis of energy level diagram, laser induced pump power dependence and blackbody radiation theory. The heat associated/incandescence‐like light is originated due to heating induced by the nonradiative relaxation followed by sensitization (Yb → Er) and Yb−Yb dimer formation. The synthesized phosphor emits effective broad band white colour emission under high pump power and colour co‐ordinates (white colour: 0.34, 0.32) were located in the chromaticity diagram. Intrinsic optical bistability (IOB) behavior shows the hysteresis‐like loop originated upon variation in the laser pump power. The observed high temperature at point of irradiation of the prepared nanocrystalline phosphor is about ∼ 2442 K at 1430 mW, which is high as compare to tungsten bulb (2400 K for 100 W). The developed phosphors can be useful in white light production, solar cell efficiency enhancement, switchable bistable and as light to heat converter.