8/3/2019 The Nanotech Revolution in Solar

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The nanotech revolution in solar power 

Posted on March 6, 2008 by lightbucket| 7 Comments 

Nanotechnology promises to deliver a breakthrough is solar cell fabrication. Newnanoparticle inks are being used to make spray-on solar cells. By replacing vacuumdeposition with printing, these nanoparticle inks enable continuous roll-to-roll production of solar panels. Nanotechnology looks set to transform the economics of solar energy.

 Nanosolar‟s first solar panels. 

“The real innovation is that we‟re trying to move the photovoltaics industry from theeconomics of the semiconductor business to the economics of the printing business.”

Erik Straser, MDV-Mohr Davidow Ventures,investor in Nanosolar Inc. [1] 

Traditional solar cells are fabricated using vacuum deposition. A batch of substrate wafers isplaced in a vacuum chamber, the chamber is evacuated, and the semiconductor material isdeposited onto the substrate. The completed solar cells are then removed from the vacuumchamber, and the next batch of substrate material is put in. The process is slow, and thevacuum processing requires expensive capital equipment.

While vacuum deposition technology has certainly been a good way to make half-inch widecomputer chips, it is poorly suited to producing solar panels by the acre. That‟s why solar

panels have remained uneconomic as energy sources.

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Breakthroughs in nanotechnology have transformed the picture. Several companies havedeveloped nanoparticle inks that can be sprayed onto flexible substrates to form layers of semiconductor. A solar panel can simply be  printed onto a roll of thin foil. These processesdon‟t need vacuum chambers, and in many cases they can even use conventional printing

equipment.

It‟s a clean break with the past. The vacuum deposition processes inherited from the

semiconductor industry have been replaced with spray-on ink technologies more akin to theprocesses used in the printing industry. These nanotech processes can produce cheap solarpanels by the acre, finally delivering on the promise of low-cost solar energy. 2008 looks likea defining year for these technologies, as some of the key companies move from developmentto large scale production.

Here are four of the most prominent companies in printable nanoparticle ink technology:

  Nanosolar Inc. 

The best known company in the field is Nanosolar. With its talent for self-promotion,it has served as the poster boy for the technology. Founded in 2002 [2] by the serialtechnology entrepreneur Martin Roscheisen, Nanosolar has raised over $100 m infunding [3], and famously counts the Google founders Sergey Brin and Larry Pageamong its investors. The company has developed a nanoparticle semiconductor ink  [4] that can simply be printed onto a roll of conductive substrate material. The process ismany times cheaper and faster than conventional semiconductor processing methods.Nanosolar shipped its first solar panels in December 2007 [5]. It claims that itsproducts halve the system cost of solar panels [6].

  HelioVolt Corporation HelioVolt has also developed a solar cell technology based on a spray-on nanoparticleink. Like Nanosolar‟s, it is based on a semiconductor called copper indium gallium

diselenide, or CIGS. The ink can be sprayed onto a variety of construction materials,such as glass and steel, to produce so-called “building integrated photovoltaic”

(BIPV) [7] systems. HelioVolt raised $101 m in venture capital investment in 2007,and in December 2007 it announced plans to build its first factory [8].

  International Solar Electric Technology (ISET) International Solar Electric Technology is the longest established company workingon CIGS nano-ink technologies. Formed in 1985 [9], it had been pursuing thisapproach long before it became fashionable. It hasn‟t sought investment, preferring to

rely on government R&D contracts to develop its technology. In contrast to the high-

tempo, high-profile nature of the venture capital funded companies, it has developedat a slower pace.  Konarka Technologies, Inc. 

Konarka‟s Power Plastic ® solar cells.

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  Konarka„s founders include the Nobel prize winner Alan J. Heeger, a pioneer insemiconducting polymers. Konarka‟s technology uses a fullerene ink deposited onto a

polymer to form a polymer:fullerene solar cell [10]. Like CIGS semiconductor inks, thefullerene ink can be printed inexpensively onto flexible substrates using roll-to-rollmanufacturing. The company raised $45 million in 2007 [11], on top of its earlier

financing. It demonstrated the first inkjet printed solar cells in early 2008[12]

.

Companies like these have made solar energy one of the hottest investment opportunities inthe semiconductor industry. They promise commercially viable solar power that can matchthe price of grid electricity. They look set to free the solar energy industry from thesubsidised niche it currently occupies. They also threaten to wipe out some of the establishedplayers – these companies have a truly disruptive technology