Thin-Film CIGS Photovoltaic Technology; Annual Technical Report, Phase I; 16 April 1998 - 15 April 1999

This report describes work performed by Energy Photovoltaics, Inc. (EPV) under Phase I of this subcontract. EPV's new FORNAX process for CIGS formation is capable of producing devices with high V{sub oc} (>600 mV) and no dark aging effects. Parameters of the best device so far are V{sub oc} = 611 mV, J{sub sc} = 27.5 mA/cm{sup 2}, FF = 74.5%, and efficiency = 12.5%. A 34-cm{sup 2} 16-cell minimodule was produced using FORNAX CIGS with V{sub oc} = 9.58 V, I{sub sc} = 52.0 mA, FF = 69.8%, and efficiency = 10.2%. A new version of EPV's linear evaporation source was developed with improved rate and uniformity for Cu deposition over a width of 45 cm. Using the new linear source, the FORNAX process was implemented on 0.43-m{sub 2} substrates in EPV's CIGS pilot line, with V{sub oc} = 537 mV and FF = 70.3% being achieved on a device. The EPV Subteam of the National CIS R&D Team has produced Cd-free ZnO/CIGS devices on NREL CIGS using the ROMEAO process (reaction of metal and atomic oxygen) for ZnO deposition. After soaking, the best device exhibited a V{sub oc} of 565 mV and an efficiency of 12.3%. Novel bias drive methods were devised for field soaking/anti-soaking experiments as a function of time and temperature. Scaling laws and an activation energy of 0.51 eV were found. Thermally stimulated capacitance reveals the existence of three distinct contributions to ZnO/CIGS device capacitance, two appearing to be gap-state effects and one related to net doping concentration. The coating time of the sputtered pilot-line ZnO:Al has been reduced by a factor of 3 while maintaining film quality. The deposition rate is 48 A s{sup -1}. Plans are under way to increase the substrate size from 0.43 m{sup 2} to 0.79 m{sup 2}

Printed Nanostructures for Organic Photovoltaic Cells and Solution‐Processed Polymer Light‐Emitting Diodes

We review the progress on printing‐based technologies for organic electronic devices, especially organic photovoltaic (OPV) cells and polymer light‐emitting diodes (PLEDs). First we discuss recent efforts to introduce interdigitated nanostructures on the order of tens of nanometers to the photoactive layers of OPV cells using nanoimprint lithography including a soft‐printing process developed in our research group that can easily produce sub‐20 nm scale organic semiconductor nanopillars. Second, we review solution‐processible printing technologies such as gravure printing, screen printing, blade coating, and slot–die coating for high‐throughput manufacturing of PLEDs.Illuminating results: This article reviews the progress on printing‐based technologies for organic electronic devices, especially organic photovoltaic (OPV) cells and polymer light‐emitting diodes (PLEDs), including solution‐processible printing technologies such as gravure printing, screen printing, blade coating, and slot–die coating for high‐throughput manufacturing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111088/1/340_ftp.pd

The market for building integrated photovoltaics in the UK

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Photovoltaics for housing in the UK

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Structural characterization of annealed Si1-x Cx /SiC multilayers targeting formation of Si nanocrystals in a SiC matrix

Amorphous Si1-xCx /SiC multilayer films were prepared by alternating deposition of Si-rich Si1-xCx and near-stoichiometric SiC layers by using magnetron sputtering. The as-deposited films were annealed at different temperatures Ta from 800 to 1100 oC. The influence of Ta and Si content in the Si-rich layer on the layered structural stability and on the formation of Si and/or SiC nanocrystals NCs is investigated by a variety of analytical techniques, including x-ray reflectivity XRR, x-ray diffraction XRD, transmission electron microscopy TEM, Raman spectroscopy, and Fourier transform infrared spectrometry FTIR. XRR showed that Si1-xCx /SiC multilayers annealed at temperatures of up to 800 oC retain their layered structure. XRD revealed that Si NCs were formed in samples with a high Si content in the Si-rich layer for Ta 800 oC. At annealing temperatures of 900 oC or greater, the formation of Si NCs was accompanied by the formation of -SiC NCs. Additionally, the formation of Si and SiC NCs was confirmed by TEM imaging and Raman spectroscopy. The Si-NC size obtained from the TEM micrographs is within the range of 3-5 nm. The -SiC NCs are smaller 2-3 nm than Si NCs. Raman analysis identified an 9 cm-1 Raman peak shift in the Si-NC peak to a lower energy with respect to that for bulk Si. FTIR Si-C bond absorption spectra exhibited narrowing of the full width at half maximum and a peak shift toward a higher wave number with increasing Ta. This behavior can be explained by an increase in order as well as an increase in the number of Si-C bonds

Fabrication and electrical characteristics of Si nanocrystal/c-Si heterojunctions

Heterojunctions HJs were fabricated from p-type Si nanocrystals Si NCs embedded in a SiC matrix on an n-type crystalline Si substrate. Transmission electron microscopy revealed that Si NCs are clearly established, with sizes in the range of 3-5 nm. The HJ diodes showed a good rectification ratio of 1.0 104 at ±1.0 V at 298 K. The ideality factor, junction built-in potential, and open-circuit voltage are 1.24, 0.72 V, and 0.48 V, respectively. Measurement of temperature-dependent I-V curves in forward conduction suggests that, in the medium voltage range, junction interface recombination can be described as the dominant current transport mechanism

PV systems on houses connected to the electricity network

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