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Thermochromic (TC) glazing could provide a significant reduction of energy consumption in curtain wall buildings.

Window coatings with dynamic solar transmittance represent an excellent opportunity to reduce building heating and cooling loads, which account for >40% of the energy consumed by the built environment.

The thermochromic properties of bilayer films consisting of a nanostructured VO2 under-layer and top-layers of ZnO, SnO2 or WO3 are presented. In each case, the VO2 under-layer was deposited by electric field assisted AACVD on a fluorine doped tin oxide coated glass substrate, with the metal oxide top-layer deposited using sol-gel spin coating. The deposited films were analysed and characterised using scanning electron microscopy, X-ray powder diffraction, variable temperature UV/Vis/NIR spectroscopy, X-ray photoelectron spectroscopy, glow discharge photoelectron emission spectroscopy and contact angle measurements. Compared to bare VO2 films, the bilayer films exhibit superior thermochromic properties, with dramatic increases in the visible light transmittance (T-vis), integrated luminous transmittance (T-lum) and solar modulation (T-sol). The thermochromic efficiency was also improved in some cases, with a reduction in the hysteresis loop width to ca. 10 degrees C, and a decrease in the transition temperature (T-c), which was as low as 44 degrees C and 43 degrees C for VO2/ZnO and VO2/SnO2 films, respectively. The best balance of thermochromic, thermal protection and aesthetic properties was achieved for ZnO coated films, with the VO2 under-layer deposited at a field strength of 1500 V m(-1) under a negative DC bias (T-c = 47 degrees C, T-lum = 61.6%, T-vis = 68% and T-sol = 6%).

Surface-enhanced Raman spectroscopy (SERS) has been widely utilised as a sensitive analytical technique\ud for the detection of trace levels of organic molecules. The detection of organic compounds in the gas\ud phase is particularly challenging due to the low concentration of adsorbed molecules on the surface of the\ud SERS substrate. This is particularly the case for explosive materials, which typically have very low vapour\ud pressures, limiting the use of SERS for their identification. In this work, silver nanocubes (AgNCs) were developed\ud as a highly sensitive SERS substrate with very low limit-of-detection (LOD) for explosive materials\ud down to the femtomolar (10−15 M) range. Unlike typical gold-based nanostructures, the AgNCs were found\ud suitable for the detection of both aromatic and aliphatic explosives, enabling detection with high specificity\ud at low concentration. SERS studies were first carried out using a model analyte, Rhodamine-6G (Rh-6G), as\ud a probe molecule. The SERS enhancement factor was estimated as 8.71 × 1010 in this case. Further studies\ud involved femtomolar concentrations of 2,4-dinitrotoluene (DNT) and nanomolar concentrations of 1,3,5-trinitroperhydro-1,3,5-triazine\ud (RDX), as well as vapour phase detection of DNT.

We report the fast amplitude modulation of a quantum cascade laser emitting in single-mode operation in the terahertz frequency range by employing compact, integrated devices based on the interplay between plasmonic antenna arrays and monolayer graphene. By acting on the carrier concentration of graphene, the optical response of these plasmonic resonances was modified. The modulator’s characteristics have been studied by using both time domain spectroscopic laser systems, yielding the broad frequency response of these resonant arrays, and quantum cascade lasers, providing us with a narrow and stable laser source, a mandatory prerequisite for the determination of the modulation speed of these devices. The measured modulation speed exhibits a cutoff frequency of 5.5 MHz ± 1.1 MHz. These results represent the first step toward the realization of fast integrated circuitry for communications in the terahertz frequency range.