Triboelectric nanogenerators (TENGs) can be incorporated into modern electronic devices requiring sustainable, renewable, and reliable microscale energy sources. We report the first use of human hair, which is known to be a highly triboelectric material, for the fabrication of biobased TENGs. Ethanolic NaOH was used to dissolve hair, and two simple fabrication techniques, bar- and spin-coating methods, were used to prepare hair-based films on electrode substrates. The dissolved hair paste has somewhat different chemical composition from original hair, but the hair-based film has almost the same level as the untreated human hair in the triboelectric series. The spin-coated film is thinner and has more even surface compared with the bar-coated one, and exhibits better performance in triboelectric generation. The TENG using a spin-coated hair film produced the maximum peak-to-peak voltage of 103 V and the power density of 60 mW m–2 across a 1.2 MΩ resistor; using the TENG device, an array of LEDs was in situ lighted without the aid of energy-collecting capacitors. A biowaste human hair offers the advantage of easy accessibility and processability into a highly tribopositive material for TENGs, and our work thus broadens the choice of positive tribo-materials and offers a novel approach for fabricating cost-effective, high efficiency, and biobased TENGs.

The development of a novel method for the fabrication of low-cost, transparent, conducting glass (F–-doped SnO2 layer on soda–lime glass, FTO) by a specially developed atomized spray pyrolysis technique using cheap soda–lime glass in place of commercially used expensive glass at a comparatively lower temperature of 450 °C is presented. The use of these FTO plates in dye-sensitized solar cells (DSCs) will also be described. The optimum temperature of 450 °C for the FTO layer on soda–lime glass is obtained by carrying out atomized spray pyrolysis of the precursor solution onto the soda–lime glass substrate at several different temperatures and by characterizing the materials obtained at each temperature by X-ray diffraction analysis. The FTO layers formed at 450 °C have also been characterized by scanning electron microscopy (SEM) for morphology, grain size, and film thickness and by UV–visible transmittance spectroscopy for the optical transmission in the visible range. The electrical properties of the FTO film prepared at 450 °C are estimated by the van der Pour method and Hall measurements. The FTO films have a uniform texture with smaller grains (≥50 nm) embedded in cages formed by larger particles (≤450 nm). The presence of large grains is important for transparent conducting glass applications. The average film thickness, estimated from the SEM images, is 560 nm. The material possesses superior electrical properties such as electronic conductivity, electron mobility, and carrier density of 1.71 × 103 S cm–1, 10.89 cm2 V–1 s–1, and 9.797 × 1020 cm–3, respectively, at room temperature. This low-cost technique, which uses cheap soda–lime glass for the fabrication of FTO, is better suited for commercialization. The DSCs fabricated using these FTO plates, with the cell configuration of FTO on soda–lime glass/interconnected TiO2 nanocrystalline layer/N719 dye/I–, I3 – electrolyte/mirror-type chromium-coated and lightly platinized FTO electrode, give a maximum light-to-electricity efficiency of 10.4% under AM 1.5 (100 mW cm–2) illumination for a cell active area of 0.25 cm2.

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