Claes-Göran Granqvist

Bio: Claes-Göran Granqvist is an academic researcher from Uppsala University. The author has contributed to research in topics: Electrochromism & Thin film. The author has an hindex of 73, co-authored 535 publications receiving 31523 citations. Previous affiliations of Claes-Göran Granqvist include Chalmers University of Technology & Texas A&M University.

Electrochromic dc Sputtered Nickel-Oxide-Based Films: Optical Structural, and Electrochemical Characterization

Abstract: NiO films were made by dc magnetron sputtering of Ni in O2. The grain size was ~10 nm and the crystal structure was cubic. Subsequent electrochemical treatment in KOH established electrochromism. The material was studied by cyclic voltammetry, in situ measurements of optical transmittance and mechanical stress, spectral infrared reflectometry, and spectrophotometric measurements in the 0.35–2.5 μm range. Electrochemical data showed that electrochromic bleaching was associated with proton insertion. P-polarized infrared reflectance showed OH stretching vibrations representative of “free” OH for the bleached state and OH in the presence of hydrogen bonds for the coloured state. The luminous and solar transmittance could be varied between 80% and 20% and between 74% and 24%, respectively. The electrochromism is produced by absorption modulation.

Graphene photonics and optoelectronics

Abstract: The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential lies in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultrawideband tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light-emitting devices to touch screens, photodetectors and ultrafast lasers. Here we review the state-of-the-art in this emerging field.