Principal component analysis luminescence thermometry of Ce3+ – case study of BaF2:Ce3+ single crystals

Luminescence thermometry based on Ce³⁺-doped materials is limited by the lack of well separated emission bands and the nanosecond timescale of the 4f–5d transition, which complicate conventional temperature-readout methods. In this work, we demonstrate the application of principal component analysis (PCA) to enhance the temperature sensitivity of BaF₂:Ce³⁺ single crystals. A crystal was grown by the vertical Bridgman method and characterized structurally and spectroscopically. Temperature-dependent photoluminescence spectra were recorded in the 300–550 K range under 270 nm LED excitation. PCA was applied to the emission spectra, enabling dimensionality reduction and extraction of a principal component (PC₁) that exhibits a strong monotonic dependence on temperature. This PCA-based method achieves an average temperature resolution of ∼1 K, overcoming the limitations of traditional luminescence intensity ratio techniques for Ce³⁺ systems. These results highlight the potential of PCA for practical high-precision luminescence thermometry using Ce³⁺-doped materials.