A novel back-side light-trapping structure for thin silicon solar cells

Decreasing silicon consumption is one of the most important ways of reducing the cost of solar cells. High-quality light trapping provides the possibility of making thinner silicon solar cells without sacrificing optical efficiency. In this work we introduce an advanced bi-periodic back-side structure with promising light-trapping properties. The structure combines high coupling efficiency of light to oblique travelling modes with the ability of keeping the light within the solar cell for multiple reflections between the front and the rear side. We have done numerical simulations of light trapping for normal incidence in our structure, and we show that our structure with real materials holds the potential to exceed the light trapping of an ideal Lambertian surface. We also investigate the behaviour of our light-trapping structure as a function of angle and state of polarization, and compare it to Lambertian behaviour

Photochromic mechanism in oxygen-containing yttrium hydride thin films: An optical perspective

Oxygen-containing yttrium hydride thin films exhibit photochromic behavior: Transparent thin films reversibly switch from a transparent state to a photodarkened state after being illuminated with UV or blue light. From optical spectrophotometry and ellipsometry measurements of the transparent state and photodarkened state, it is concluded that the photochromic effect can be explained by the gradual growth, under illumination, of metallic domains within the initial wide-band-gap semiconducting lattice. This conclusion is supported by Raman measurements

Synergetic improvement of stability and conductivity of hybrid composites formed by PEDOT:PSS and SnO nanoparticles

In this work, layered hybrid composites formed by tin oxide (SnO) nanoparticles synthesized by hydrolysis and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) have been analyzed. Prior to the composite study, both SnO and PEDOT:PSS counterparts were characterized by diverse techniques, such as X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), photoluminescence (PL), atomic force microscopy (AFM), optical absorption and Hall effect measurements. Special attention was given to the study of the stability of the polymer under laser illumination, as well as the analysis of the SnO to SnO_2 oxidation assisted by laser irradiation, for which different laser sources and neutral filters were employed. Synergetic effects were observed in the hybrid composite, as the addition of SnO nanoparticles improves the stability and electrical conductivity of the polymer, while the polymeric matrix in which the nanoparticles are embedded hinders formation of SnO_2. Finally, the Si passivation behavior of the hybrid composites was studied

A new thin film photochromic material: Oxygen-containing yttrium hydride

In this work we report on photochromism in transparent thin film samples of oxygen-containing yttrium hydride. Exposure to visible and ultraviolet (UV) light at moderate intensity triggers a decrease in the optical transmission of visible and infrared (IR) light. The photo-darkening is colour-neutral. We show that the optical transmission of samples of 500 nm thickness can be reduced by up to 50% after one hour of illumination with light of moderate intensity. The reaction is reversible and samples that are left in the dark return to the initial transparent state. The relaxation time in the dark depends on the temperature of the sample and the duration of the light exposure. The photochromic reaction takes place under ambient conditions in the as-deposited state of the thin-film samples.Comment: Accepted for publication in Solar Energy Materials and Solar Cell

Hydrogen complexes in Zn deficient ZnO

acceptedVersio

Bone mineral density and explanatory factors in children and adults with juvenile dermatomyositis at long term follow-up; a cross sectional study

Background Juvenile dermatomyositis (JDM) is the most common idiopathic inflammatory myopathy in children and adolescents. Both the disease and its treatment with glucocorticoids may negatively impact bone formation. In this study we compare BMD in patients (children/adolescence and adults) with long-standing JDM with matched controls; and in patients, explore how general/disease characteristics and bone turnover markers are associated with BMD. Methods JDM patients (n = 59) were examined median 16.8y (range 6.6–27.0y) after disease onset and compared with 59 age/sex-matched controls. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD of the whole body and lumbar spine (spine) in all participants, and of ultra-distal radius, forearm and total hip in participants ≥20y only. Markers of bone turnover were analysed, and associations with outcomes explored. Results Reduced BMD Z-scores (<−1SD) were found in 19 and 29% of patients and 7 and 9% of controls in whole body and spine, respectively (p-values < 0.05). BMD and BMD Z-scores for whole body and spine were lower in all patients and for < 20y compared with their respective controls. In participants ≥20y, only BMD and BMD Z-score of forearm were lower in the patients versus controls. In patients, BMD Z-scores for whole body and/or spine were found to correlate negatively with prednisolone use at follow-up (yes/no) (age < 20y), inflammatory markers (age ≥ 20y) and levels of interferon gamma-induced protein 10 (IP-10) (both age groups). In all patients, prednisolone use at follow-up (yes/no) and age ≥ 20y were independent correlates of lower BMD Z-scores for whole body and spine, respectively. Conclusion In long-term JDM, children have more impairment of BMD than adults in spine and whole-body. Associations with BMD were found for both prednisolone and inflammatory markers, and a novel association was discovered with the biomarker of JDM activity, IP-10