Tailoring thermal mass for enhanced infrared response in Sb–Bi–Te-based printed thermocouples

Recent developments in the fabrication of advanced materials have broadened the application space of thermoelectric (TE) technologies beyond conventional solid-state cooling and energy harvesting. A compelling application is the use of TE materials to facilitate photo-thermoelectric (PTE) infrared sensing via a dual-stage energy conversion process: radiation-to-thermal followed by thermal-to-electric. Here, we report a detailed study on dimensionally controlled, screen-printed PTE infrared sensors fabricated on flexible substrates. We tune the thickness of Bi–Sb–Te-based p- and n-type printed TE films via ink formulation to study the thermal mass dependent optical, microstructural, mechanical and thermoelectric properties, and their combined effect on PTE sensing performance. Single-legged and double-legged printed PTE sensors were fabricated using p- and n-type Bi–Sb–Te materials. Under CO$_2$ laser irradiation with 10.6 µm wavelength, the double-legged PTE sensor showed a peak responsivity of 107.7 mV W$^{−1}$. Finite-element simulations were also performed to validate the experimental findings. These results highlight thermal mass engineering as an effective pathway toward high-performance, flexible, non-contact human–machine interaction systems and proximity sensors.