We report that the rare-earth (RE) ion, Sm-doped ZnO, acts as white light emitting vacuum ultraviolet (VUV) phosphors and possesses an ultrahigh color rendering index (CRI) and color quality scale (CQS). The VUV-excited emission spectra measured from the synchrotron source reveal the emergence of multi-color emission bands in the visible-IR region and substantially depend on the concentration of S m 3 + ions. A mechanism is proposed to elucidate the origin behind the high-energy bandgap excitation of the host charge carrier and subsequent energy transfer to the S m 3 + states leading to additional green-yellow-orange emission bands of S m 3 + ( 4 G 5 / 2 → 6 H J ( J = 5 / 2 , 7 / 2 , a n d 9 / 2 ) ) . High-quality cool white light (correlated color temperature 5600 K) having CIE coordinates (0.33, 0.35) with a CRI as high as 95.89 and a CQS value of 94.49 is achieved for Z n 0.985 S m 0.015 O under synchrotron VUV radiations. This Letter demonstrates that RE activated ZnO-based phosphors are expected to be a promising candidate in solid state lighting, as well as plasma display devices.

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