Multi-type electronic transitions induced multi-color light emitting of bismuth in tantalate used for WLED

Abstract

The photoluminescence behaviors of bismuth-activated phosphors are fascinating and puzzling due to the existence of multi-type electronic transitions. Therefore, the development of novel bismuth-activated phosphors is an important objective of many researchers. In this work, a marvellous photoluminescence characteristic of Bi3+ ion was observed in a cubic phase of Y3TaO7 (YTO), which performs multi-color light emissions, although there is only one cationic crystallographic site for accommodating Bi3+ dopant. Under near-ultraviolet (NUV) light excitation, Bi3+-activated YTO produces a considerably wide cyan light peaked at 477 nm with a full width at half maximum (FWHM) of 130 nm. Moreover, with the increase of excitation wavelength, the emission band was detected to have an extraordinary red shift from 477 to 547 nm and broadening, and its FWHM reaches up to 160 nm. Combined with the crystal and electronic structure of YTO, an interpretation was proposed to shed light on the photoluminescence behavior of Bi3+ ion in this system, which indicates that multi-type electronic transitions are supposed to produce the surprising luminescence properties of Bi3+ ion. The detailed discussion was processed in this work, which is expected to enhance people's comprehension for the luminescence behavior of Bi3+ ion.