Transparent glass-ceramics functionalized with EuSiO3 constrained BaF2:Eu2+ nanocrystals: theoretical design and experimental fulfillment towards an efficient spectral converter

Abstract

Spectral conversion is feasible for various photonic or photoelectric device efficiency improvement, through harvesting extra photons out of the response region. But the challenge is still to fulfill spectral converters with overlapped photoluminescence (PL) emission and high optical transmittance windows. Here, a type of transparent Eu²⁺ doped fluorosilicate glass-ceramic is developed to enhance the UV resistance as well as maintain the high photovoltaic performance of organic solar cells (OSCs). For such purposes, we theoretically design glasses with a molecular dynamics simulation and experimentally prepare glass samples composed of immiscible fluoride and silicate glass sub-phases. Appropriate thermal treatment is then applied to grow EuSiO₃ constrained BaF₂:Eu nanocrystals from the fluoride sub-phases. The precipitation of BaF₂:Eu nanocrystals enables Eu³⁺/Ba²⁺ lattice site substitution and further Eu³⁺ → Eu²⁺ reduction. EuSiO₃ serves as a diffusion barrier preventing the continuous growth of nanocrystals. These microstructures thus support the high visible optical transmittance >91%, strong UV (250–400 nm) to visible (400–600 nm) spectral converted photoluminescence, and a relatively high quantum yield (43.49%). Finally, we apply this spectral converting glass-ceramic on the ITO/PEDOT:PSS/PBDB-TF:Y6/PFN-Br/Ag OSC to demonstrate a significant improvement of UV resistance of the organic active layer without any loss of photovoltaic performance.