Frequency conversion plays a key role in controlling relaxation dynamics in rare-earth-doped materials and underlies numerous photonic applications, particularly in photovoltaics. In this context, spectral conversion aims to optimize solar radiation absorption by shifting poorly absorbed wavelengths toward ~980 nm, corresponding to the bandgap region of crystalline silicon. Glass–ceramic systems have been shown to be especially effective for tailoring energy transfer mechanisms between rare earth ions [1]. Among them, silica–hafnia binary matrices have emerged as promising hosts for incorporating rare earth ions into hafnia nanocrystals, resulting in enhanced luminescence efficiency and expanded application potential.
In this work, we investigate the Tb³⁺/Yb³⁺-mediated down-conversion process in silica–hafnia glass–ceramic thin films as a strategy to improve the spectral response of silicon-based solar cells. The films were prepared via a sol–gel spin-coating method followed by an appropriate thermal treatment, enabling precise control over composition, morphology, and optical properties [2].
Photoluminescence measurements performed under 476 nm excitation reveal a strong emission from Yb³⁺ ions associated with the 2F5/2→2F7/2 transition after Tb3+ excitation, demonstrating an efficient energy transfer from Tb³⁺ to Yb³⁺. These results confirm the efficiency of the down-conversion mechanism in the silica–hafnia glass–ceramic system and highlight its relevance for photovoltaic spectral conversion applications.
In summary, this study demonstrates that Tb³⁺/Yb³⁺-codoped silica–hafnia glass–ceramic thin films constitute a promising and tunable system for efficient spectral down-conversion in silicon-based photovoltaic technologies.
[1] Salima El Amrani , Lamyae Oulmaati , Giancarlo C. Righini , Maurizio Ferrari, Mohammed Reda Britel, Adel Bouajaj. Ceramics International (2025) 51(12) 16645-16649. https://doi.org/10.1016/j.ceramint.2024.10.448.
[2] Salima El Amrani, Michael Sun, Sirona Valdueza-Felip, Fernando B. Naranjo, Mohammed Reda Britel, Maurizio Ferrari, Adel Bouajaj, Effect of temperature and excitation power on down-conversion process in Tb3+/Yb3+-activated silica-hafnia glass-ceramic films,Ceramics International,2024,ISSN 0272-8842 .https://doi.org/10.1016/j.ceramint.2024.06.392.
