Nitrogen doped graphene prepared via an inhomogeneous hydrothermal reaction was applied to DSCs as a cathode material, yielding a cell efficiency of 8.2%.

We report here a reliable and reproducible single-step (without post-annealing) fabrication of phase-pure p-type rhombohedral CuAlO2 (r-CuAlO2) thin films by reactive magnetron sputtering. The dependence of crystallinity and phase compositions of the films on the growth temperature was investigated, revealing that highly-crystallized r-CuAlO2 thin films could be in situ grown in a narrow temperature window of ∼940 °C. Optical and electrical property studies demonstrate that (i) the films are transparent in the visible light region, and the bandgaps of the films increased to ∼3.86 eV with the improvement of crystallinity; (ii) the conductance increased by four orders of magnitude as the film was evolved from the amorphous-like to crystalline structure. The predominant role of crystallinity in determining CuAlO2 film properties was demonstrated to be due to the heavy anisotropic characteristics of the O 2p-Cu 3d hybridized valence orbitals.

A novel strategy to achieve high performance thin-film transistors based on carrier concentration-graded InGaZnO channels using Al2O3-passivated HfO2 as a dielectric layer was established.

A simplified reaction−diffusion model is proposed to show the origins of inefficient charge transport in dye-sensitized solar cells (DSCs) based on bulky complex redox shuttles. In this model, diffusion length of the oxidized species in electrolyte solution is defined and assumed to depend on the average density of the conduction band electrons. The resulting quasi-linear equations enable the density profiles of electrons and redox shuttles to be calculated directly. When the charge transport of a DSC is under diffusion limitation, diffusion overpotential is shown to serve as an additional potential, which maintains a high level of electron density in TiO 2 film, even at short circuit. The photocurrent output is therefore considerably limited because of the accelerated recombination reaction. Moreover, short circuit current density is confined by the diffusion limited current density under inefficient charge transport, and close to the photocurrent density at high diffusivity of redox shuttles. For the DSC with slow redox shuttles, a critical thickness of TiO 2 film is observed. This is the maximum thickness allowing the charge transport to be free from diffusion limitation. The optimized film thickness yielding the maximum power conversion efficiency is shown to be slightly less than the critical thickness, which implies the potential usage of the critical thickness in designing the state-of-art DSC.