Efficient Luminescent Coatings Constituted of Hybrid Sol-Gel Matrixes Embedding YVO₄:Eu³⁺ Nanocrystals

This study focuses on the development of luminescent coatings incorporating YVO₄:Eu³⁺ nanocrystals (NCs) into a hybrid sol-gel matrix and investigates the influence of the NC size and loading rate on the optical properties. Two distinct hydrothermal protocols were employed to synthesize YVO₄:Eu³⁺ NCs with average sizes of approximately 340 and 10 nm, respectively. Their structural, morphological and optical characterizations were performed using various techniques. Interestingly, the smaller YVO₄:Eu³⁺ NCs exhibit the highest external quantum yield of about 44% without the necessity of additional thermal treatment. The hybrid matrix, composed of 3-glycidoxypropyltrimethoxysilane (GPTMS) and zirconium propoxide, demonstrates excellent transparency, mechanical stability, and uniform dispersion of the NPs. Spin-coating techniques were used to fabricate homogeneous coatings on glass substrates with NP loadings of 2 and 5 wt %. Upon UV excitation, the different samples exhibit strong red emission centered at 619 nm attributed to the ⁵D₀ → ⁷F₂ transition of Eu³⁺ ions. The angular distribution of the emission depends on the NC size. Larger NCs significantly reduce photon leakage at the edges due to optical scattering.