The illumination performance and energy savings of a solar fiber optic lighting system have been verified in a study hall--corridor interior. The system provides intensive white light with a high luminous flux of 4500 lm under 130000 lx direct sun radiation at a 10 m fiber distance from the sun-tracking light collector. The color temperature that describes the light color perceived is 5800 ± 300 K, i.e. close to the direct sunlight outside, and the color rendering index (86), that describes how well colors are rendered under the light source, is higher for the solar lights than for the supplementary fluorescent lights (77). Thus this high quality solar lighting improves the visibility of all kinds of objects compared to the fluorescent lights. Annual lighting energy savings of 19% in Uppsala, Sweden and 46% in southern Europe were estimated for a study hall interior, as well as 27% and 55% respectively in an interior illuminated 16 h per day all days of a year.

Composite semiconductors provide routes for realizing high-performance electronic devices, but for many applications of such devices, low-cost manufacturing techniques are desirable. We have engineered a 3 orders of magnitude enhancement of the ultraviolet photoresponse of ZnO thin films, fabricated "in situ" by drop-on-demand inkjet printing, and then capped with CdS nanoparticles by dip coating. As a consequence, the decay time of the photoresponse is reduced to about 4 ms. Thus, capping with CdS not only suppresses the detrimental passivation layer of ZnO thin films, but also generates an interfacial carrier transport layer to reduce the probability of carrier recombination.SECTION Electron Transport, Optical and Electronic Devices, Hard Matter Z inc oxide is a versatile technologically important material for developing optical and electronic components, especially in the emerging area of transparent electronics. Availability of more advanced facilities to synthesize and characterize materials at a nanoscale has revived interest to exploit the photoconductive properties of ZnO, especially in the UV regime, although such studies have been in progress for a long time since the 1950s. 1 The intrinsic UV properties of ZnO are very useful for developing nanoscale optoelectronic devices, because it is a wide bandgap semiconductor with good carrier mobility and can be doped to become both n-, and p-type. 2,3 However, it is difficult to obtain high UV conductivity from ZnO because of the existence of surface states that give rise to a high surface recombination velocity and thereby reduce the photocurrent generation and decreases the sensitivity. 4-6 One route to effectively passivate the unwanted surface states is to develop a second semiconductor layer. From this point of view, there are as of late a few studies on charge transfer at the interface between ZnO and the surrounding ambience in composites like CdS/ZnO, 7-9 SiO 2 /ZnO, 10,11 ZnO/PVK, 12 In 2 O 3 /SnO 2 /ZnO, 13 PVP/ZnO 14 mainly to understand the photoelectrochemical properties of such systems. Recently Fang et al. 8 have found that a CdScap layer acts as a passivating layer to suppress the detrimental surface states of ZnO nanowalls, which affects the intersurface carrier transport layer and thereby enhances the UV photoconductivity at the nanowalls. We have studied this phenomenon in inkjetted ZnO films with controlled porosity and film thickness.For cost-effective fabrication of device components, inkjet printing has emerged as an attractive direct patterning technique, especially for integrated circuit applications, because of its versatility of delivering picoliter volumes of solutions or suspensions in well-defined patterns with high spatial accuracy and noncontact deposition. 15-17 Recent reports on a few studies of inkjet-printed ZnO-based nanowire fieldeffect-transistors, indicate a promising future for inkjet printing to develop device applications. 18,19 On the basis of our earlier work, 20 in this letter, we demonstrate the possibility to eng...

Magnetic and optical properties of three-dimensional fcc-structured magnetic photonic crystals (MPCs), consisting of SiO2 spheres, in the size range 260–680 nm, embedded with 0–6.4 wt % Fe3O4 nanoparticles have been investigated. In the wide spatial angle transmission spectra for these crystals at normal incidence of light in the UV-visible range, five photonic band gaps (PBGs) due to Bragg diffraction from different crystal planes have been observed. The Bragg wavelengths (λB) of PBGs in both the nonmagnetic and MPCs of the same structure are found to depend linearly on the sphere size. From the slope of this linear function the calculated effective refractive index is found to increase with the concentration of the magnetite nanoparticles in the MPCs, and is consistent with the result calculated from the average dielectric constant. We also find λB of PBGs are dependent on the angle of the incidence of the light. Furthermore, for small angles this angular dependency is more strongly dependent on the polarization of incident light for MPCs than for the non-MPCs. Thus, magnetic nanocomposite PCs can be designed to incorporate additional functionality in the development of potential magneto-optical devices.

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