Performance modulation of contact electrification nanogenerators by controlling the doping concentration of fluorine-doped tin oxide

Contact electrification nanogenerators (CENGs) were fabricated, and their output performance was modulated by controlling the doping concentration of fluorine-doped SnO2 (FTO) thin films. As the fluorine source content was increased from 0.8 to 1.2 mM during spray pyrolysis deposition, the electron concentration in the FTO thin film increased from 1.84 × 1020 to 5.22 × 1020 cm−3, which is much larger than the Mott critical carrier concentration of SnO2. The output voltage and current from the CENGs which were fabricated by the aluminium and FTO surfaces increased from 2.76 to 5.66 V and from 0.003 to 0.005 μA/cm2 when controlling the electron concentration in the FTO layer from 5.22 to 1.84 × 1020 cm−3. The modulation of the output performance of the CENGs originated from the change in work function of the FTO layer by Burstein-Moss shift.