Learn more about R&D chemical mechanical polishing by requesting our FREE informational CD.

Download our CMP White Paper


FREE subscription
Subscribe for free to receive each issue of Semiconductor Today magazine and weekly news brief.


15 October 2007


AFRL increases funding of Ascent’s tandem PVs

The US Air Force Research Laboratory (AFRL) recently increased its funding of Ascent Solar Technologies Inc of Littleton, CO, USA for the development of thin-film tandem photovoltaic (PV) cells by up to $749,000 more over a 27-month period. This follows the initial phase 1 Small Business Innovative Research (SBIR) contract from AFRL in May.

Based on the firm’s existing technology for flexible monolithically integrated copper indium gallium diselenide (CIGS) deposited on plastic substrates, the tandem solar cells consist of two solar cells in a stack, with the top cell collecting the blue portion of the solar spectrum and the bottom cell collecting the rest of the visible spectrum. “This program will demonstrate the ability to make solar cells using a new material system that has the potential to serve as the top cell of a new and innovative tandem solar cell configuration,” says Dr Joseph Armstrong, VP and chief technology officer.

“While our baseline CIGS that utilizes a single junction to convert the sun’s energy has been performing very well, we are always striving to increase cell performance that can potentially lead to further reductions in system-level costs to the end user,” says Armstrong. “Efficient conversion of the sun’s energy is very critical to space and near-space applications, as higher efficiencies correlate directly to smaller, lighter-weight solar arrays, and significantly lower launch cost,” he adds. “Likewise, in terrestrial and building integrated photovoltaic (BIPV) applications, such as roofing tiles and building facades that operate at elevated temperatures, future tandem devices can provide a significant advantage over existing thin film by delivering more power in less area.” It is believed that the technology has the potential to demonstrate a targeted efficiency level reaching 20%.

Since 1995, US government and other externally funded programs have provided over $60m for the development of flexible CIGS technology at first R&D commercialization company ITN Energy Systems Inc (founded in 1994) and, subsequently (after transfer of intellectual property, staff and $3.5m in R&D contracts in January 2006), to Ascent Solar (which was spun off in October 2005).

US government funding from the AFRL, as well as the National Aeronautics and Space Administration, has sponsored a significant portion of development for space and near-space applications.

Previously, in March, AFRL granted Ascent a modification of an extra $607,365 for the extension (to March 2009) of an original $925,283 contract for the development of a flexible substrate. “Depositing at a higher temperature than is possible with our baseline plastic substrates can lead to higher performance that is required for space and near-space applications,” says Armstrong. “We have already demonstrated efficiencies of nearly 14% in the space environment with high-temperature substrates, which is equivalent to well over 15% for terrestrial applications, and we believe that further performance improvement is possible,” he adds. “In addition, the fabrication process used in these high-performance cells is directly related to our existing prototype monolithically integrated manufacturing operations, and will be compatible with our manufacturing line.”

In July 2006, Ascent completed a $16.5m initial public offering. Funds are being used to establish an initial 1.5MW production plant in Denver, CO, USA for its large roll format modules. In December, Ascent chose manufacturing equipment suppliers with expertise in roll-to-roll processing of thin films on plastic substrates, including the UK’s General Vacuum Equipment, Germany’s Stangl Semiconductor Equipment AG and Japan’s Hiranokohnon.

Between Q3/2007 and the end of this year, all tools should be installed, for initial operation in early 2008. The firm says it aims to ramp up quickly to support expansion to large-scale production at a 25MW plant by the end of 2009, then look into building a larger facility, ultimately at 100MW-scale production levels and above.

See related items:

Ascent Solar awarded DoE contract for high-rate CIGS process development

Ascent Solar raises over $20m from warrant conversion

Ascent Solar shareholders approve increase in Norsk Hydro stake from 23% to 35%

Energy producer Hydro invests in Ascent Solar for CIGS-based flexible solar cells

Search: Photovoltaic cells CIGS