Significance of host׳s intrinsic absorption band tailing on Ce3+ luminescence quantum yield in borate glass

In glass, the valence band to conduction band transition exhibits an extended band tailing. This band tailing is an intrinsic property of the glass and is consists of the exponential Urbach tail and the defects induced weak absorption tail. The extended nature of the band tailing incorporates finite absorption of the electromagnetic radiation in the band gap region. In this work, the contribution of such host׳s intrinsic band tail absorption on Ce3+ luminescence quantum yield has been investigated in the borate glass host. The absorption spectra revealed that the host's band tailing effectively overlaps the Ce3+ excitation bands in the borate glass that causes an unwanted absorption loss during the Ce3+ excitation. This gives rise to a significant reduction in the measured external quantum efficiency of Ce3+ luminescence. A comparison of standard quantum yield (~42%) and host corrected quantum yield (~62%) suggests that the host's intrinsic absorption gives rise to about 20% reduction in Ce3+ luminescence quantum yield in the studied borate glass.