An interface-engineered HMS/PANI thermoelectric device for 3D printer waste heat harvesting

The development of flexible, high-performance thermoelectric materials is necessary due to the growing demand for sustainable energy conversion from waste heat sources. In this work, we present higher manganese silicide/polyaniline (HMS/PANI) composite thin films that exhibit a hierarchical interface design, which partially decouples the typically interrelated thermoelectric parameters for waste heat recovery from working 3D printers. Structural characterization studies - XRD and SEM - confirm the well-dispersed HMS network with good interfacial quality. Through systematic composition optimization, we achieved enhanced electrical conductivity, 438 S m^-1, and a simultaneous increase in the Seebeck coefficient of 72 μV K^-1 at 80% HMS content. This enhancement results from hierarchical composite engineering, achieved by percolation-driven charge transfer at HMS/PANI interfaces and energy filtering effects, which also increase carrier concentration. The optimized composition exhibits an enhanced power factor of 2.3 μW (mK²)^-1. Phonon engineering suppresses the lattice thermal conductivity relative to pure PANI, thereby maximizing the thermoelectric performance of composites. I-V characterization confirms the ohmic transport behaviour across all compositions. Device output characterization demonstrates a maximum power generation of 0.33 nW at ΔT = 70 K. Real-time application demonstration on an operating 3D printer reveals stable performance by generating 6-8 mV output, validating its functionality for autonomous IoT energy harvesting systems. This work establishes HMS/PANI composites as a flexible thermoelectric material where sophisticated composite design transcends individual phase limitations, paving the way for practical thermoelectric energy harvesting from diverse waste heat sources.