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.

Radiative cooling and frost formation on surfaces with different thermal emittance: theoretical analysis and practical experience.

Abstract: Radiative cooling power was computed as a function of the emittance c, of an exposed surface, air temperature, humidity, etc. from the LOWTRAN 5 code. Meteorological data were then used to make semiquantitative estimates on how often frost will form on a surface with given epsilon(s). Practical tests, using SnO(2)-covered glass with epsilon(s) approximately 0.2, demonstrated that a low-emittance coating can prevent frost formation and maintain transparency of a window exposed to the clear sky.

Electrochromic W1–x–yTixMoyO3 Thin Films Made by Sputter Deposition: Large Optical Modulation, Good Cycling Durability, and Approximate Color Neutrality

Abstract: Tungsten oxide thin films are used in electrochromic devices such as variable-transmittance “smart windows” for energy efficient buildings with good indoor comfort. Two long-standing issues for WO3 thin films are their limited durability under electrochemical cycling and their blue color in transmission. Here, we show that both of these problems can be significantly alleviated by additions of titanium and molybdenum. We found that ∼300 nm-thick films of sputter deposited W1–x–yTixMoyO3 are able to combine a midluminous transmittance modulation of ∼70% with good color neutrality and durability under extended electrochemical cycling. The Ti content should be ∼10 at. % in order to achieve durability without impairing transmittance modulation significantly, and the Mo content preferably should be no larger than 6 at. % in order to maintain durability. Hence, our results give clear guidelines for making three-component mixed-oxide thin films that are suitable for electrochromic “smart windows”.

Structure and optical absorption of liyv2o5 thin films

Abstract: Films of lithiated vanadium pentoxide (LiyV2O5) are of interest for ion storage in electrochromic “smart windows” and in lithium battery technology. In this paper we study optical absorption of LiyV2O5 films in the 0.3 < λ < 2.5 μm wavelength range, encompassing visible light and solar radiation, in relation to the micro-structure.

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.