Luminescence and energy transfer mechanism in Ce3+ and Gd3+ ions in bismuth borate glass

In recent years, researchers have been attracted to the tuning of the solar spectrum through a coverglass as a means to enhance the efficiency of a photovoltaic cell by improving the energy transfer mechanism. In this study, energy transfer mechanism was investigated between Gd3+ and Ce3+ ions in a bismuth borate glass. Cerium ions (0.1–2.5 mol%) were doped into a bismuth borate glass using a versatile melt-quenching technique in an ambient atmosphere under various experimental conditions. The luminescence and optical properties were examined in relation to the concentration of cerium. The structural changes in the glass matrix that occurred as a result of variation in the concentration were investigated using Fourier transform infrared spectroscopy. To ensure the incident light passage through the glass is not compromised due to self-absorption, optical absorption measurements were carried out to investigate the presence of resonant plasmonic absorption of nanoclusters. The energy bandgap of Ce3+-doped glass decreased from 2.772 to 2.671 eV due to dopant concentration-induced structural change in the glass matrix. The photoluminescence properties of the present samples confirmed their suitability for luminescent down converter applications. At UV excitation wavelength of 325 nm, the Ce3+-doped samples down-shifted the solar spectrum and gave the most prominent emission band at 448 nm due to the 5d-4f transition of Ce3+. The optimum concentration was observed as 0.3 mol%, further increase in the dopant concentration led to a decrease in the emission intensity may be due to the conversion of Ce4+ into Ce3+ ions [47], [48]. In the energy transfer, Gd3+ transfers energy non-radiatively to Ce3+ due to the equivalent energy level 6P7/2 of Gd3+ and 5d energy level of Ce3+.