In dye-sensitized solar cells, nanoporous structure of TiO 2 is very important for efficient cell because lots of dye molecules are adsorbable and they are the source of the photocurrent. However, the internal impedance of TiO 2 is relatively large and it limits the performance. For better performance, vanadium was doped into TiO 2 in this work. Doping different material generally improves the characteristics and functions of original materials. Vanadium doping has some advantages such as the reduction of internal resistance, the improvement of chemical stability and high absorption. Especially, reduced internal resistance is so helpful for better electron transfer in TiO 2 network. Various amounts of vanadium were applied and photovoltaic performance, internal impedance and absorbance were measured in order to verify the effect of vanadium doping. As a result, vanadium doping improved the overall performance from 6.01 to 6.81% with decreased internal resistance although adsorbed dye amount was reduced by decreased surface area and open circuit voltage was also decreased by the change of band-gap energy.
We present Spitzer/IRAC 4.5 μm transit photometry of GJ 3470 b, a Neptune-size planet orbiting an M1.5 dwarf star with a 3.3 day period recently discovered in the course of the HARPS M-dwarf survey. We refine the stellar parameters by employing purely empirical mass-luminosity and surface brightness relations constrained by our updated value for the mean stellar density, and additional information from new near-infrared spectroscopic observations. We derive a stellar mass of M = 0.539 +0.047 −0.043 M and a radius of R = 0.568 +0.037 −0.031 R . We determine the host star of GJ 3470 b to be metal-rich, with a metallicity of [Fe/H] = +0.20 ± 0.10 and an effective temperature of T eff = 3600 ± 100 K. The revised stellar parameters yield a planetary radius R p = 4.83 +0.22 −0.21 R ⊕ that is 13% larger than the value previously reported in the literature. We find a planetary mass M p = 13.9 +1.5 −1.4 M ⊕ that translates to a very low planetary density, ρ p = 0.72 +0.13 −0.12 g cm −3 , which is 33% smaller than the original value. With a mean density half of that of GJ 436 b, GJ 3470 b is an example of a very low-density low-mass planet, similar to Kepler-11 d, Kepler-11 e, and Kepler-18 c, but orbiting a much brighter nearby star that is more conducive to follow-up studies.
Here, we report the characteristics of a novel organic/inorganic hybrid photovoltaic device using a Si quantum dot (QD) layer synthesized by multi-hollow discharge plasma chemical vapor deposition. The hybrid device has a p–i–n structure, which consists of a crystalline Si (c-Si) substrate, a Si QD layer, and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). We have examined the absorption coefficient and photoconductivity of Si QD layers, and confirmed electricity generation from Si QD layers. We have measured the current–voltage characteristics and incident photon-to-current conversion efficiency (IPCE) of c-Si/Si QD/poly(3,4-ethylenedioxythiophene) (PEDOT) hybrid solar cells. This hybrid device shows an energy conversion efficiency of 2.84%, a short-circuit current of 6.84 mA/cm2, an open-circuit voltage of 0.73 V, and a fill factor of 0.58. A high IPCE value of 82.8% is obtained at a short wavelength of 460 nm.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.