NIR light-triggered green emitting perovskite-based phosphor for optical thermometry and future molecular logic gate applications

Abstract

<title>Abstract</title> Er³⁺ and Yb³⁺ doped CaTiO₃ phosphors were prepared using combustion synthesis. The synthesized samples underwent comprehensive analysis to evaluate their structural, morphological, and optical properties. This analysis encompassed techniques such as X-ray powder diffraction, field emission scanning electron microscopy, and photoluminescence investigations. A meticulous luminescence investigation was conducted on the synthesized samples. The study revealed that erbium ions (Er³⁺) exhibited distinct green and red emissions when subjected to excitation by a 980 nm infrared (IR) source. These emissions were attributed to the ²H_11/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 electronic transitions, respectively. The up-conversion process of the synthesized phosphor, CaTiO₃:Yb³⁺, Er³⁺, was examined through the analysis of power-dependent emission spectra. Subsequently, a rate equation model was proposed to elucidate this process. To evaluate the thermosensitive capabilities of the phosphor, the temperature-dependent responses of different thermally and non-thermally linked emission lines associated with Er³⁺ were investigated. Temperature sensing measurements were performed between 303 and 583 K using the fluorescence intensity ratio technique. Relative sensitivities of 1.14, 1.66, 0.15, and 0.33% K^{− 1} were observed across different thermally and non-thermally linked transitions. By utilizing heat and IR excitation as inputs, the versatility of the synthesized phosphor in designing logic gates was demonstrated. This scheme enabled us to attain a notable switching ratio of approximately 170.86% for the AND gate and about 72.28% for the INHIBIT gate. The synthesized phosphor exhibits considerable potential as a versatile material suitable for applications in both future molecular logic devices and optical thermometry.