Synergistic enhancement of electric heating and infrared radiation characteristics in La_0.7Sr_0.3Al_0.5Mn_0.5O₃@Pt thin film enabling electro-thermal-optical conversion

Non dispersive infrared gas sensor represents the leading trend in gas sensor technology with the infrared light source serving as a critical component. The working principle of infrared light sources involves energy conversions of electricity to heat and thermal to light, which is independently carried out by the electric heating layer and the infrared radiation layer. The complex multi-film structure of infrared light sources leads to high heat transfer loss, long response time, and increased heat capacity. This study defines a coral-like porous thin film containing Pt nanoparticles loaded on La_0.7Sr_0.3Al_0.5Mn_0.5O₃ (La_0.7Sr_0.3Al_0.5Mn_0.5O₃@Pt), created from the concept of multi-functional materials. This thin film exhibits outstanding electric heating and infrared radiation properties. The co-doping of A-site and B-site of LaAlO₃ made the La_0.7Sr_0.3Al_0.5Mn_0.5O₃ thin film not only possessed certain oxygen vacancies and lattice distortion, but also formed a coral-like micro-porous structure. The loading of Pt nanoparticles possesses high electrical conductivity and localized surface plasmon resonance effect, further nanostructured the coral-like micro-porous structure of La_0.7Sr_0.3Al_0.5Mn_0.5O₃ thin film. Benefit from the synergistic effect of the co-doping of Sr²⁺ and Mn²⁺and loading of Pt nanoparticles, the resistance of the La_0.7Sr_0.3Al_0.5Mn_0.5O₃@Pt thin film was reduced by 9 orders of magnitude. Meanwhile, its electric heating performance was improved by a factor of 11.29 compared to the LaAlO₃ thin film. Moreover, the infrared absorptivity of La_0.7Sr_0.3Al_0.5Mn_0.5O₃@Pt thin film exhibited in the range of 2.5–25 μm was ~ 96.7%, which is 1.60 times higher than that of LaAlO₃ thin film, indicating a significant improvement in the infrared radiation performance.