P-type nc-SiOx:H emitter layer for silicon heterojunction solar cells grown by RF-PECVD

Silicon heterojunction solar cells (SHJ) with thin intrinsic layers are well known for their high efficiencies. A promising way to further enhance their excellent characteristics is to enable more light to enter the crystalline silicon (c-Si) absorber of the cell while maintaining a simple cell configuration. Our approach is to replace the amorphous silicon (a-Si:H) emitter layer with a more transparent nanocrystalline silicon oxide (nc-SiOx:H) layer. In this work, we focus on optimizing the p-type nc-SiOx:H material properties, grown by radio frequency plasma enhanced chemical vapor deposition (rf PECVD), on an amorphous silicon layer. 20 nm thick nanocrystalline layers were successfully grown on a 5 nm a-Si:H layer. The effect of different ratios of trimethylboron to silane gas flow rates on the material properties were investigated, yielding an optimized material with a conductivity in the lateral direction of 7.9×10-4 S/cm combined with a band gap of E04 = 2.33 eV. Despite its larger thickness as compared to a conventional window a-Si:H p-layer, the novel layer stack of a-Si:H(i)/nc-SiOx:H(p) shows significantly enhanced transmission compared to the stack with a conventional a-Si:H(p) emitter. Altogether, the chosen material exhibits promising characteristics for implementation in SHJ solar cells

Association of exposure to air pollution and green space with ovarian reserve hormones levels

Exposure to air pollution has been associated with adverse health effects while exposure to greenspace has been associated with public health benefits. However, the available evidence on the association of exposure to air pollution with ovarian reserve markers is still scarce, with no study on such an association with greenspace exposure. Therefore, this study aimed to investigate the association of exposure to particulate matter with diameter of less than 1, 2.5 and 10 μm (PM1, PM2.5, PM10), traffic indicators (distance from women's residence to major roads and total street length in different buffers around women's residential address) and greenspace indicators (residential surrounding greenspace and distance to green spaces) with serum levels of anti-müllerian hormone (AMH) and follicle stimulating hormone (FSH) as markers of ovarian reserve. This cross-sectional study was based on 67 women residing in Sabzevar, Iran (2018). Basal serum levels of FSH and AMH were measured by the enzyme-linked immunosorbent assays (ELISA). Land use regression models were used to estimate PMs concentrations at residential addresses and the average of normalized difference vegetation index (NDVI) in different buffers was used to characterize residential surrounding greenspace. Multiple linear regression models were developed to estimate the association of AMH and FSH with exposure to air pollution, traffic, and greenspace (one at a time) controlled for relevant covariates. In fully adjusted models, there was an inverse association between exposure to PM1, PM2.5 as well as total street length in 100 m buffer around women's residence and AMH level (β = �0.89, 95 confidence interval (CI): �1.43, �0.35, P-value � 0.01, β = �1.11, 95 CI: �1.67, �0.55, P-value � 0.01 and β = �0.76, 95 CI: �1.48, �0.50, P-value = 0.03, respectively). Moreover, increase in distance from home to nearest major road as well as residential surrounding greenspace (100 m buffer) and decrease in residential distance to a green space larger than 5000 m2 were associated with increase in serum level of AMH. However, we did not observe any significant association between exposure to air pollution, traffic, and greenspace with FSH level. Overall, our findings supported a beneficial association of exposure to greenspace and detrimental association of exposure to air pollution with ovarian reserve. © 2020 Elsevier Inc