Engineering the luminescence and photothermal properties of metal complex Ruphen functionalized with silver nanoparticles for infrared human detection

A luminescence quenching enhanced infrared (IR) detector has been developed to achieve highly sensitive recognition of human body by adding metallic luminescence quenchers. Spherical Ag NPs were mixed with Ru(phen) 3 2+ complex to obtain temperature-sensitive Ag/Ruphen/PVDF films. The relationships among luminescence output, temperature rise and silver addition were investigated and a satisfactory combination of enhanced luminescence factor and temperature change was found with an addition of 5 mol% of 71 nm Ag NPs. It is found that the metal-enhanced luminescence output is insignificant compared to its thermal ingredient since silver provides additional possible electron transfer channels, promoting non-radiative transitions and weakening luminescence. Besides, the Ag NPs induced additional temperature rise bringing further reduction of luminescence. The photothermal effect of Ag NPs can attain a higher temperature change under a certain IR radiation without an observed degradation of luminescence output. A coupled optical-thermal model was established to explain the schematic of the constructed infrared thermal detector. The non-invasive detections of moving and stationary human by the detector were successfully demonstrated. The work tends to provide an engineered optical-thermal model in luminophores and construct highly sensitive luminescence-based infrared thermal detectors.