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Novel zinc oxide (ZnO) inks via mixing a soluble aqueous ZnO precursor with ZnO nanoparticles suitable for low temperature processing of the thin film transistors (TFTs) were prepared. ZnO TFTs produced from the proposed ZnO mixture ink exhibited significantly enhanced field effect mobility of 1.75 cm 2 V −1 s −1 and an on/off ratio of 5.89 × 10 8 even at low processing temperature of 250 °C. Various structural analyses were performed to investigate the influence of ZnO nanoparticles inclusion into the thin film nanostructure on the structural, chemical, and electrical characteristics of the ZnO TFTs.

For thermoelectric (TE) applications, the surface of exfoliated black phosphorus (BP) can be successfully functionalized with Au nanoparticles (NPs), leading to significantly enhanced TE performance for a controlled Au NP content. A facile and selective decoration of metal species on the defect sites of BP is achieved by the spontaneous formation of Au NPs on the surface of BP through a redox reaction of Au precursors. Such a heterostructure provided by the Au decoration of BP enhances electrical conductivity (from 0.001 to 63.3 S cm −1 ) through tuning of the charge carrier concentration and retains the initial Seebeck coefficient of BP. Consequently, the TE power factor of the Au-decorated BP increases significantly to 68.5 µV m −1 K −2 , which is 2740 times that of the pristine BP. More significantly, in contrast to the severe degradation of the pristine BP in the air, surface-functionalized BP exhibits excellent stability upon exposure to air for a long period, which is beneficial for practical TE applications. Given these interesting and unique properties of Au-decorated BP, a vertical TE generator with a high power output of 79.3 nW (ΔT = 2 °C) is prepared by using the Au-decorated BP as a p-type TE material.

Small-bundled single-walled carbon nanotube (SSWCNT) nanocomposite films with two different conjugated polymers were facilely prepared by using a micronizing mill. The influence of the difference in the electronic structures and molecular orientations of poly­(3-hexylthiophene) (P3HT) and poly­(diketopyrrolo­pyrrole–selenophene) (PDPPSe) on the thermoelectric properties of polymer/SSWCNT nanocomposites was systematically investigated. Planar-shaped PDPPSe with stronger π–π interaction, compared to that in P3HT, naturally forms a dense surface microstructure with SSWCNT by easily wrapping the SSWCNT surface. Furthermore, the inherent crystalline orientation of PDPPSe effectively enhances the electrical conductivity of the SSWCNT nanocomposite film by inducing the alignment of SSWCNT bundles in an in-plane direction. In the electronic structure of the composite, PDPPSe lowers the interfacial energy barrier between the polymer and SSWCNT to induce the carrier-filtering effect, which can facilitate charge transport from the polymer to SSWCNT. The PDPPSe/SSWCNT nanocomposite exhibits a considerably increased electrical conductivity of 537.7 S cm–1 and a higher Seebeck coefficient of 62.5 μV K–1 compared to those of the P3HT/SSWCNT nanocomposite. The optimized power factor of the PDPPSe/SSWCNT nanocomposite is 210 μW m–1 K–2, which is about 10 times higher than that of the P3HT/SSWCNT nanocomposite. The thermoelectric generator fabricated from PDPPSe/SSWCNT displays a high open-circuit voltage (V oc) of 8.5 mV and short-circuit current (I sc) of 162.8 μA, resulting in a maximum output power of 0.35 μW at ΔT = 10 °C.

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