Charge localization induced tunable thermopower in ZnSb intercalated polyaniline:CSA flexible films

Abstract

Modulating doping levels and nanofillers blending has facilitated optimization of electrical properties in polymeric nanocomposite films for thermoelectric applications. Herein we report, free-standing flexible films of PANI:CSA/ZnSb polymer nanocomposites, with varying nanofillers ZnSb ratios, to realize charge localization induced enhancement in power factor (≈10 times) and thermopower (≈6 times) within the protonated PANI:CSA. Le Bail refinement of the XRD pattern reveals lattice expansion and reoriented chain conformation in the pseudo-orthorhombic PANI structure due to ZnSb intercalation. The thermopower, enhanced to ≈50 μV/K at room temperature, was tunable due to the suppressed bipolaronic states and associated charge localization, resulting in an improved power factor of ≈10 μW/m·K². The synthesized polymeric films exhibit excellent mechanical durability, retaining ∼90 % of their electrical conductivity after 2000 bending cycles. A flexible thermoelectric generator (FTEG) fabricated using six PANI:CSA/70 wt% ZnSb films produced an output voltage of ∼0.9 mV on a human wrist and ∼6.7 mV under a temperature gradient of ∼50 K, highlighting prospects of charge localization in improving the low and smeared Seebeck response in conducting polymers like PANI and their potential for wearable thermoelectric energy harvesting applications.