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

Luminescence thermometry based on Ce 3+ -doped materials is limited by the lack of well separated emission bands and the nanosecond timescale of the 4 f –5 d 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 BaF 2 :Ce 3+ 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 (PC 1 ) 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 Ce 3+ systems. These results highlight the potential of PCA for practical high-precision luminescence thermometry using Ce 3+ -doped materials.