Australian researchers have reported a boost in solar cell performance to be revealed at next week's big European solar-tech exhibition in Hamburg, Germany.

The improved technology was developed by a team headed by Stuart Wenham at UNSW's ARC Photovoltaic Centre of Excellence. The groundbreaking LDSE solar cell - first developed by the University of New South Wales in the mid-1990s - achieves energy-conversion efficiencies of between 18 to 19 percent in pilot production using standard commercial mono-silicon wafers.

The boost represents a ten to 15 per cent performance improvement compared to standard screen-printed solar cells using the same wafers and materials. UNSW's tech-transfer division, NewSouth Innovations will reveal the technology at the 24th European Photovoltaic Solar Energy Exhibition (21st to 24th September)in Hamburg, Germany.

Professor Wenham has invented or co-invented eight suites of solar cell technologies that have been licensed to solar cell makers around the world. These companies have annual production volumes valued at hundreds of millions of dollars in an industry that is now the world's fastest-growing energy sector.

"This next-generation LDSE technology will be ready for commercial production within two years," says Professor Richard Corkish, head of the UNSW School of Photovoltaic and Renewable Energy Engineering.

"By then it's expected to achieve a 20 to 25 percent performance margin over standard mono-silicon screen-printed solar cells on the market. The technology is well-suited to large-scale commercial production because of its simple, low cost, high-throughput characteristics."

In 2008 UNSW reasserted its leadership in solar cell technology by reporting the first silicon solar cell to achieve the milestone of 25 per cent efficiency. The ARC Photovoltaic Centre of Excellence already held the world record of 24.7 per cent for silicon solar cell efficiency.

A revision of the international standard by which solar cells are measured delivered the significant 25 per cent record to the team led by Professors Martin Green and Stuart Wenham and widened their lead on the rest of the world.

The latest LDSE cells use a laser in the presence of a phosphorus doping source to melt the silicon lying beneath the cell's overlying antireflection coating. This incorporates phosphorus dopants into the molten silicon, removing the dielectric layer and thereby exposing the silicon surface. Subsequent self-aligned metal contact formation to these exposed regions is achieved with light-induced plating. This results in metal lines only 20-25 microns wide with perfect alignment to the localised heavily-doped regions.

The antireflection coating is retained in non-metallised regions and acts as a plating mask, providing excellent surface passivation and antireflection qualities. An important benefit of the LDSE technology is its suitability for multicrystalline silicon wafers and other lower cost wafer types. UNSW has achieved pilot production energy-conversion efficiencies of 17 percent using multicrystalline silicon wafers.

Lower-cost wafers typically degrade badly when subjected to prolonged high temperature thermal processes, making them incompatible with other high efficiency technologies. LDSE technology overcomes this limitation by using a laser to locally apply the necessary heat for localised formation of heavily doped regions. This means the remainder of the wafer isn't subjected to high temperatures and avoids the problems associated with prolonged high temperature thermal processes.

Higher efficiency than standard screen-printed solar cells

Lower production costs

Suitable for mono- or multi-crystalline wafer

Doesn't damage the crystal like other laser-doping methods

World solar photovoltaic (PV) market installations reached a record high of 5.95 gigawatts (GW) in 2008, representing growth of 110 per cent over the previous year, according to the Marketbuzz(TM) 2008 Annual World Solar Photovoltaic Industry Report. Europe accounted for 82 per cent of world demand, led by Spain and Germany. The US is the world's third biggest market, followed by Korea, Italy and Japan.

World solar cell production reached 6.85 GW in 2008, up from 3.44 GW a year earlier. The PV industry generated US$37.1B in revenues in 2008, while successfully raising over US$12.5B in equity and debt, up 11 per cent on the prior year. The cumulative installed PV-capacity worldwide is set to grow at a compound annual growth rate of around 28 per cent in 2009-2013, according to new research report from RNCOS.

Commercial: Neil Simpson, phone: +612 9385 6536, mobile: +61-418-603-166, n.simpson@nsinnovations.com.au

Research: Richard Corkish, phone: +61-410-496-759, r.corkish@unsw.edu.au

NSi MEDIA: Dan Gaffney, phone: +61-411-156-015