Energy filtering and anisotropic structural response in polyaniline:CSA hybrids for flexible thermoelectrics

Abstract

Recent advances in polymer nanocomposites have opened promising routes for engineering carrier characteristics, phonon dynamics and conformational disorders, paving the way for next-generation thermoelectric materials. Herein, we report the development of free-standing, flexible films of Mg_0.99Cu_0.01Ag_0.97Sb_0.99 nanofiller-incorporated PANI:CSA polymer nanocomposites. The hybrid nanocomposites showed nearly a tenfold increase in the power factor and Seebeck coefficient, accompanied by a synergistic reduction (∼100%) in thermal conductivity, yielding a thermoelectric figure of merit (zT) of ∼0.13 (±0.02) at ∼300 K. Transport analysis employing the Kang–Snyder (KS) framework and Semi-Localized Transport (SLoT) modeling reveals an invariant scattering exponent in the semi-localized regime, implying preserved diffusive polaronic transport, improved interfacial connectivity, and energy-filtering-driven mobility enhancement, while structural and spectroscopic analyses reveal anisotropic lattice adaptation, dedoping-induced polaron stabilization, bond charge distribution, and preserved pseudo-orthorhombic order in PANI. To validate its practical applicability, a flexible thermoelectric generator was fabricated, producing an output voltage of ∼11.6 mV and underscoring the promise of Te-free, interface-engineered polymer–inorganic hybrids for wearable energy harvesting.