Optoelectronic and photovoltaic devices with low-reflectance surfaces

Low angle V-grooves are provided in the target surfaces of optoelectronic or photovoltaic devices such as solar cells and photodetectors. The low angle V-grooves increase the efficiency of the devices by promoting total internal reflection of light reflected from the target surface at the interface of the coverglass and the external environment

Towards an overheating risk tool for building design

PurposeThe work set out to design and develop an overheating risk tool using the UKCP09 climate projections that is compatible with building performance simulation software. The aim of the tool is to exploit the Weather Generator and give a reasonably accurate assessment of a building's performance in future climates, without adding significant time, cost or complexity to the design team's work.Methodology/approachBecause simulating every possible future climate is impracticable, the approach adopted was to use principal component analysis to give a statistically rigorous simplification of the climate projections. The perceptions and requirements of potential users were assessed through surveys, interviews and focus groups.FindingsIt is possible to convert a single dynamic simulation output into many hundreds of simulation results at hourly resolution for equally probable climates, giving a population of outcomes for the performance of a specific building in a future climate, thus helping the user choose adaptations that might reduce the risk of overheating. The tool outputs can be delivered as a probabilistic overheating curve and feed into a risk management matrix. Professionals recognized the need to quantify overheating risk, particularly for non‐domestic buildings, and were concerned about the ease of incorporating the UKCP09 projections into this process. The new tool has the potential to meet these concerns.Originality/valueThe paper is the first attempt to link UKCP09 climate projections and building performance simulation software in this way and the work offers the potential for design practitioners to use the tool to quickly assess the risk of overheating in their designs and adapt them accordingly.</jats:sec

Investigation of anodic and chemical oxides grown on p-type InP with applications to surface passivation for n(+)-p solar cell fabrication

Most of the previously reported InP anodic oxides were grown on a n-type InP with applications to fabrication of MISFET structures and were described as a mixture of In2O3 and P2O5 stoichiometric compounds or nonstoichiometric phases which have properties similar to crystalline compounds In(OH)3, InPO4, and In(PO3)3. Details of the compositional change of the anodic oxides grown under different anodization conditions were previously reported. The use of P-rich oxides grown either by anodic or chemical oxidation are investigated for surface passivation of p-type InP and as a protective cap during junction formation by closed-ampoule sulfur diffusion. The investigation is based on but not limited to correlations between PL intensity and X-ray photoelectron spectroscopy (XPS) chemical composition data

Historical Precision of an Ozone Correction Procedure for AM0 Solar Cell Calibration

In an effort to improve the accuracy of the high altitude aircraft method for calibration of high band-gap solar cells, the ozone correction procedure has been revisited. The new procedure adjusts the measured short circuit current, Isc, according to satellite based ozone measurements and a model of the atmospheric ozone profile then extrapolates the measurements to air mass zero, AMO. The purpose of this paper is to assess the precision of the revised procedure by applying it to historical data sets. The average Isc of a silicon cell for a flying season increased 0.5% and the standard deviation improved from 0.5% to 0.3%. The 12 year average Isc of a GaAs cell increased 1% and the standard deviation improved from 0.8% to 0.5%. The slight increase in measured Isc and improvement in standard deviation suggests that the accuracy of the aircraft method may improve from 1% to nearly 0.5%

Alpha voltaic batteries and methods thereof

An alpha voltaic battery includes at least one layer of a semiconductor material comprising at least one p/n junction, at least one absorption and conversion layer on the at least one layer of semiconductor layer, and at least one alpha particle emitter. The absorption and conversion layer prevents at least a portion of alpha particles from the alpha particle emitter from damaging the p/n junction in the layer of semiconductor material. The absorption and conversion layer also converts at least a portion of energy from the alpha particles into electron-hole pairs for collection by the one p/n junction in the layer of semiconductor material

Measurement and Characterization of Concentrator Solar Cells II

Concentrator solar cells are continuing to get more consideration for use in power systems. This interest is because concentrator systems can have a net lower cost per watt in solar cell materials plus ongoing improvements in sun-tracking technology. Quantitatively measuring the efficiency of solar cells under concentration is difficult. Traditionally, the light concentration on solar cells has been determined by using a ratio of the measured solar cell s short circuit current to that at one sun, this assumes that current changes proportionally with light intensity. This works well with low to moderate (<20 suns) concentration levels on "well-behaved" linear cells but does not apply when cells respond superlinearly, current increases faster than intensity, or sublinearly, current increases more slowly than intensity. This paper continues work on using view factors to determine the concentration level and linearity of the solar cell with mathematical view factor analysis and experimental results [1]

Extended Temperature Solar Cell Technology Development

Future NASA missions will require solar cells to operate both in regimes closer to the sun, and farther from the sun, where the operating temperatures will be higher and lower than standard operational conditions. NASA Glenn is engaged in testing solar cells under extended temperature ranges, developing theoretical models of cell operation as a function of temperature, and in developing technology for improving the performance of solar cells for both high and low temperature operation

A Hardware and Software Perspective of the Fifth Materials on the International Space Station Experiment (MISSE-5)

Conducting space experiments with small budgets is a fact of life for many design groups with low-visibility science programs. One major consequence is that specialized space grade electronic components are often too costly to incorporate into the design. Radiation mitigation now becomes more complex as a result of being restricted to the use of commercial off-the-shelf (COTS) parts. Unique hardware and software design techniques are required to succeed in producing a viable instrument suited for use in space. This paper highlights some of the design challenges and associated solutions encountered in the production of a highly capable, low cost space experiment package