Flexible thermoelectrics (TEs) involving simplified processeability are attractive, with limited choice of materials and low endurance, remaining as major challenges. Herein, an economic emery paper‐based thermoelectric generator (PTEG) from graphite as p‐type leg and bismuth as n‐type leg is introduced, prepared by simple bulk tracing. Tracing provides a feasible approach to modulate the TE properties, as supported by finite‐element analysis. From individual bismuth trace a power factor of 5.85 μW m−1 K−2 ≈100 °C (2.09 μWm−1 K−2 at room temperature (RT)) and for graphite a power factor 7.7 μW m−1 K−2 at ≈100 °C (≈5.1 μW m−1 K−2 at RT) is obtained. A six‐pair p–n module‐integrated PTEG drives an open‐circuit voltage of 35.8 mV producing an output power of 14.6 nW whereas from a 60‐pair PTEG, voltage ≈348 mV with ≈137.5 nW output power is produced for ΔT ≈ 70 K. The scalability of the fabricated PTEGs is understood from Seebeck voltage being directly proportional to the number of p–n modules and is further tested for harvesting waste heat from electronics. This facile approach may be extended to other organic and inorganic TE materials, contributing to the research in self‐powered heat sensors, wearables, and as thermal harvesters in IoT equipment.

Organic thermoelectric materials (OTEs) are in huge demand for their flexibility and robustness in applications of internet‐of‐things, wearables, and health monitoring devices. While choices of p‐type OTEs are widespread, there is still lack of stable (in air) n‐type systems to pair. Naphthalene‐diimides (NDIs), due to the presence of the planar‐structured electron‐deficient aromatic ring offer promising electron‐deficient building blocks to construct air‐stable n‐type semiconducting devices. Herein, an amphiphile derivative (cNDI‐1) is reported for two‐dimensional supramolecular assembly, and consequently TE measurements are carried out in a fully calibrated and standardised custom‐built Seebeck (S) set‐up. Promising S values (ca. −237 μV/K in THF and ca. −195 μV/K in water) are measured with a TE power factor of ∼0.05×10−5 μW/mK2 in THF and ∼0.6×10−5 μW/mK2 in water at room temperature. The study opens up the possibility of exploring broad range of molecular design library for newer n‐type OTEs.

Flexible and foldable paper-based thermoelectric generators (PTEGs) have drawn industrial attention due to the wide applications in heat energy harvesting and sensing. Herein, optimization of the output performances of flexible and hybrid inorganic-organic PTEGs fabricated on stationery paper substrates from poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and graphite as p-type and n-type materials, respectively, is presented. By choosing simplistic processes such as polyethyleneimine (PEI)-treated graphite pencil traces and brush-painted PEDOT:PSS films, robust and sustainable PTEG devices are fabricated. It is first time shown that different qualities of stationery papers can have significant impact on the output performance of PTEGs, attributed to their variance in substrate roughness. Thus, output powers of %1.93 and %0.68 nW for ΔT = 70 K are obtained for TE generators prepared from emery and office paper legs (four-pair assembled on Kapton), respectively, suggesting emery paper to have significant better performance. Transient flexibility and fatigue of each device type are also tested where emery paper-based PTEG appears to be more robust. A detail comparison of the device performances on the different types of paper substrates are exclusively presented experimentally and thereafter computationally validated by COMSOL modeling to predictably control and enhance the output performance of reported PTEGs.

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