Haihan Zhou

An efficient titanium foil based perovskite solar cell: using a titanium dioxide nanowire array anode and transparent poly(3,4-ethylenedioxythiophene) electrode

A titanium (Ti) foil based perovskite solar cell (PSC) is devised and prepared by employing titanium dioxide nanowire (TNW) arrays and titanium dioxide nanoparticles (TNPs) on Ti foil substrates as the electron transporting layer (ETL). The TNW array is desirable for the PSC, since it can provide direct pathways for the rapid collection and transmission of photo-generated electrons. The Ti foil substrate has many advantages such as flexibility, low sheet resistance, and excellent mechanical stability. The sunlight illuminates through the highly transparent poly(3,4-ethylenedioxythiophene) (PEDOT) film on the indium doped tin oxide/polyethylene naphthalate (ITO/PEN) substrate. The transparent PEDOT electrode can be used as the hole transporting layer (HTL) due to the well matched band positions for charge separation and transport. As a result, the Ti foil based light-weight PSC with TNW arrays yields an efficiency of 13.07% with an active area of 1.00 cm2, which is higher than that of the PSC with TNPs (9.93%). These promising results highlight the potential application of the PEDOT and Ti foil in cost-effective, large-area, and flexible PSCs.

A comparative study of graphene oxide reduction in vapor and liquid phases

Abstract Graphene oxide (GO) was reduced by formaldehyde or formic acid in vapor or liquid phases below 200 °C. The influence of the concentrations of reducing agents, reaction temperature and time on the electrical conductivity of the reduced graphene oxide (rGO) was investigated. The rGOs were characterized by XRD, XPS and Raman spectroscopy. Results show that the optimum reaction temperatures are 150 and 175 °C in the vapor phase and the liquid phase, respectively, based on the electrical conductivities of the rGOs. The ratio of the areas of the C1s peaks related to the C-C and C-O (Rcc/co) from XPS decreases with reaction time from 9 to 24 h in the vapor phase, and increases from 2 to 24 h in the liquid phase, which are in agreement with the electrical conductivities and Raman results. Gasification of carbon atoms in GO sheets may be responsible for the decrease of Rcc/co with prolonged reaction time in the vapor phase.