Download or read book Characterization of Radiation Damage in Multi junction Solar Cells Using Light biased Current Measurements written by Aaron Korostyshevsky and published by . This book was released on 2008 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Triple-junction amorphous silicon solar cells have been characterized using two techniques to identify the current-limiting component cell after a variety of radiation exposure experiments. The first technique is calculation of integrated current from quantum efficiency (QE) data, which is commonly accepted by the photovoltaics community for predicting the current output of a solar cell. This study shows that significant sources of uncertainty make quantum efficiency measurements unreliable in low quality multi-junction devices such as those that have been severely degraded by particle radiation.An alternate method is examined whereby a solar cell is illuminated by simulated air-mass zero (AM0) light and secondary filtered lamps are used to boost the current in two of the three component cells. Thorough characterization of the test condition shows that the targeted component cell limits the current of the device as a result of the boost light, making the current measured from the device under test represent the current output of the desired component cell. This method is henceforth called light-biased current measurement (LBCM). An additional benefit of the light-biased current measurement is the significantly reduced time required to make a measurement compared to quantum efficiency measurements.Successful repeatability and reproducibility experiments further validate this test method. As shown during reproducibility testing, one of the two solar simulators used introduces an expected increase in the measurement uncertainty due its unstable intensity output. The increase in variance of the data is well correlated to the estimated measurement uncertainty.
Download or read book Novel Materials Grid Design Rule and Characterization Methods for Multi junction Solar Cells written by Jingjing Li and published by . This book was released on 2012 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation addresses challenges pertaining to multi-junction (MJ) solar cells from material development to device design and characterization. Firstly, among the various methods to improve the energy conversion efficiency of MJ solar cells using, a novel approach proposed recently is to use II-VI (MgZnCd)(SeTe) and III-V (AlGaIn)(AsSb) semiconductors lattice-matched on GaSb or InAs substrates for current-matched subcells with minimal defect densities. CdSe/CdTe superlattices are proposed as a potential candidate for a subcell in the MJ solar cell designs using this material system, and therefore the material properties of the superlattices are studied. The high structural qualities of the superlattices are obtained from high resolution X-ray diffraction measurements and cross-sectional transmission electron microscopy images. The effective bandgap energies of the superlattices obtained from the photoluminescence (PL) measurements vary with the layer thicknesses, and are smaller than the bandgap energies of either the constituent material. Furthermore, The PL peak position measured at the steady state exhibits a blue shift that increases with the excess carrier concentration. These results confirm a strong type-II band edge alignment between CdSe and CdTe. The valence band offset between unstrained CdSe and CdTe is determined as 0.63 eV±0.06 eV by fitting the measured PL peak positions using the Kronig-Penney model. The blue shift in PL peak position is found to be primarily caused by the band bending effect based on self-consistent solutions of the Schrödinger and Poisson equations. Secondly, the design of the contact grid layout is studied to maximize the power output and energy conversion efficiency for concentrator solar cells. Because the conventional minimum power loss method used for the contact design is not accurate in determining the series resistance loss, a method of using a distributed series resistance model to maximize the power output is proposed for the contact design. It is found that the junction recombination loss in addition to the series resistance loss and shadowing loss can significantly affect the contact layout. The optimal finger spacing and maximum efficiency calculated by the two methods are close, and the differences are dependent on the series resistance and saturation currents of solar cells. Lastly, the accurate measurements of external quantum efficiency (EQE) are important for the design and development of MJ solar cells. However, the electrical and optical couplings between the subcells have caused EQE measurement artifacts. In order to interpret the measurement artifacts, DC and small signal models are built for the bias condition and the scan of chopped monochromatic light in the EQE measurements. Characterization methods are developed for the device parameters used in the models. The EQE measurement artifacts are found to be caused by the shunt and luminescence coupling effects, and can be minimized using proper voltage and light biases. Novel measurement methods using a pulse voltage bias or a pulse light bias are invented to eliminate the EQE measurement artifacts. These measurement methods are nondestructive and easy to implement. The pulse voltage bias or pulse light bias is superimposed on the conventional DC voltage and light biases, in order to control the operating points of the subcells and counterbalance the effects of shunt and luminescence coupling. The methods are demonstrated for the first time to effectively eliminate the measurement artifacts.
Download or read book Radiation Effects on Multi Junction Solar Cells written by Tommy L. Fifer and published by . This book was released on 2001-12-01 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: The GaInP2/GaAs/Ge monolithic high efficiency triple junction cell is the state of the art multijunction solar cell for space applications. Numerous labs have undertaken investigation into the stability of GaInP2/GaAs/Ge in response to electron radiation. Electron radiation experiments have shown that the degradation of GaInP2/GaAs/Ge solar cells is mainly caused by a decrease of the short circuit current (Isc). The investigation and interpretation of the damage mechanism from electron irradiation in Spectrolab's GaInP2/GaAs/Ge triple junction cell is the purpose of this thesis. Current voltage characteristics were measured to establish beginning of life (BOL) parameters of the solar cells and the changes that occur due to irradiation (EOL).
Download or read book Modeling and DLTS Analysis of Irradiated III V Multijunction Solar Cells written by Sheng S. Li and published by . This book was released on 1986 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research project was to develop a simple theoretical model based on Wilson's model to calculate the displacement damages introduced by either protron or electron irradiation in AlGaAs, GaAs, InGaAs and Ge. These calculations would then be applied to obtain an optimized triple junction solar cell structure using these materials with a specified end of life conversion efficiency. Empirical formulae and theoretical expressions were derived for calculating the displacement cross section, penetration depth, path length, total number of defects formed by an incident electron or protron, and the fractional loss of electron-hole pairs due to recombination loss. Formulae to calculate the degradation of short-circuit current under different electron and proton fluences and energies in AlGaAs, GaAs, InGaAs, Ge single junction solar cells and the triple junction cells formed from these materials were developed. The results of our calculations indicate that the degradation rate in each cell varies greatly, and depends critically not only the energy, fluence and the direction of the incident electrons and protons but also on the thickness of each cell in the triple junction cells. Major difficulties encountered in performing the theoretical calculations using the model developed in this report included may unknown parameters and the lack of experimental data on electron and proton damages in the AlGaAs and InGaAs solar cells for comparison with theoretical calculations. These uncertainties can be removed once the actual cell structures for the proposed triple junction cells are fabricated and measurements of radiation damage are made in these cells.
Download or read book Space Radiation Effects in Advanced Solar Cell Materials and Devices written by R. J. Walters and published by . This book was released on 2002 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the physical mechanisms governing the response of III-V based solar cells to particle irradiation is presented. The effect of particle irradiation on single and multijunction solar cells is studied through current vs. voltage, spectral response, and deep level transient spectroscopy measurements. The basic radiation response mechanisms are identified, and their effects on the solar cell electrical performance are described. In particular, a detailed analysis of multijunction In(x)Ga(1-x)P/In(y)Ga(1-y)As/Ge devices is presented. The MJ cell response is found to be more strongly affected by the internal cell structure than by the In content.
Download or read book Handbook of Space radiation Effects on Solar cell Power Systems written by William C. Cooley and published by . This book was released on 1963 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1989 with total page 1470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1971 with total page 2174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1972 with total page 918 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar Energy Update written by and published by . This book was released on 1984 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book GaAs Solar Cell Radiation Handbook written by B. E. Anspaugh and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Imaging of Minority Charge Carrier Transport in Triple Junction Solar Cell Layers written by Ted Jonathan Mills and published by . This book was released on 2006 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: An optical, contact-free method for measuring minority carrier diffusion lengths is developed and demonstrated for a range of semiconductor materials used in high efficiency triple junction solar cells. This method uses a Scanning Electron Microscope (SEM) coupled with an optical microscope. The diffusion lengths, combined with minority carrier lifetime measured via time-resolved photoluminescence, allow for the computation of minority charge carrier mobility. The technique uses images to extract diffusion length measurements from GaAs, InGaAs, and InGaP heterostructures at different SEM beam energies and probe currents. Excellent correlation between measurements shows the reproducibility of this technique. Diffusion lengths from 2-63 microns have been measured in a variety of GaAs, InGaAs, and InGaP samples. Effects of alloy ordering, doping, and lattice matching have been investigated. Several areas for further research are offered, including detailed radiation-damage mapping of solar cell layers. Further anisotropic studies of the solar cell layers are suggested to investigate the directional dependence of diffusion length within the InGaP heterostructures. Finally, new and emerging solar cell materials would benefit from this technique, allowing for the complete characterization of minority charge transport properties before growing an entire solar cell.
Download or read book Bias Dependent Radiation Damage in Silicon Solar Cells written by T. J. Cumberbatch and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Review of the Electrical Communications Laboratories written by and published by . This book was released on 1986 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Japanese Science and Technology 1983 1984 written by United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch and published by . This book was released on 1985 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research in Progress written by and published by . This book was released on 1983 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt:
