Abstract
AbstractPaper‐based thermoelectric generators are a promising and economical alternative to expensive organic conductors that are normally preferred for flexible generators. In the present work, graphite pencil traces on regular Xerox paper are successfully employed to constitute a thermoelectric generator. In conjunction with polyethylenimine polymer, the graphite traces act as both the p‐type and n‐type thermoelectric “legs,” of a graphite‐based thermoelectric generator. The fabrication method is facile and requires no conducting paste or silver paste to connect individual thermoelectric legs. A test module containing five pairs of p‐n legs is fabricated on paper to test its performance. The device produces a thermoelectric voltage of 9.2 mV, generating an output power of 1.75 nW at a temperature difference of ≈60 K. The present work demonstrates that ordinary pencil on paper may be used as the foundation for a cheap, flexible, easily disposable, and environmentally friendly thermoelectric generator.
Highlights
Paper-based thermoelectric generators are a promising and economical alternative to expensive organic conductors that are normally preferred for flexible generators
The properties of individual p-type and n-type graphite traces (Trace Design 1 (TD1)) were studied before analyzing the performance of the device (Trace Design 2 (TD2)) which are discussed
Despite the considerable increase in resistivity yielded by PEI-treatment, with the room temperature conductivity decreasing from 3.32 × 102 S m−1 for as-drawn graphite to 2.24 × 102 S m−1, the power factor was correspondingly improved by the treatment process: the measured value of 85 nW m−1 K−2 in the case of untreated graphite was increased to 100 nW m−1 K−2 after modification by PEI
Summary
Alongside the Seebeck coefficient, the electrical conductivity and power factor of a thermoelectric material are critical to its overall performance as part of a device; these measurements are plotted from room temperature to 100 °C for the as-drawn and PEI-treated TD1 devices in Figure 3c,d, respectively. In order for an application to exploit this property over the long-term, it is necessary for the device to demonstrate sustainable performance through multiple cycles of distortion To this end, changes in the Seebeck coefficient and electrical conductivity of a TD1 sample were measured over multiple bending cycles, as depicted in Figure 5a; separate but identical TD1 type samples were used for the Seebeck coefficient and electrical conductivity measurements, which are plotted in Figure 5b,c, respectively. (≈45° and ≈90°) and it was observed that the values were not much affected but a slight change of about 1 μV K−1 (Figure S1, Supporting Information)
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