Breakthrough made in boosting solar cell power

• 8 years ago (2016-01-04)
• David Flin

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The Ben-Gurion University of the Negev (BGU) and Technion-Israel Institute of Technology have announced that they have developed a new light trapping technique that enables over 30 per cent power enhancement of an ultrathin solar cell. The method was developed for hematite cells meant for hydrogen production via water splitting, but could achieve its goals for other types of cells. In addition, the technique only uses simple optical materials, adding to the sustainability and cost effectiveness of this approach.

One of the ways of increasing the cost effectiveness of solar cells is by reducing the thickness of their active light absorbing layers. The challenge is to have a thinner absorber but to sustain significant overall absorptivity. The researchers have devised optical trapping methods to trap the light within the interior of the call, causing a longer effective beam path through the active layer, raising the absorptivity.

The problem the researchers had to overcome was that in ultrathin layers, light behaves as a wave, rendering ray-based trapping ineffective. This led to the development of wave-based trapping methods, which has been less effective than ray-based methods. Therefore the researchers returned to ray optics and developed a new method that combines ray-based trapping with wave optics absorption. This was achieved by structural separation of the trapping and absorption sites within the cell. Light is first trapped in a lossless thick substrate layer that later feeds the absorption in a deep subwavelength active hematite layer.