Textured substrates raise organic solar cell efficiencies

Sara Ver-Bruggen - 13 Dec 2010

US-based researchers at the Ames Laboratory and Iowa State University have developed a process for applying a thin and uniform light-absorbing layer on textured substrates that improves the efficiencies of polymer solar cells by increasing light absorption.

The light trapping technique has the potential to improve solar cell efficiency by up to 20%, says Iowa State assistant professor and associate of the US Department of Energy's Ames Laboratory Sumit Chaudhary.

Recent years have seen efficiencies of prototype organic solar cells creep up to over 8% in 2010. But efficiencies gains are lost when lab-based processes are transferred to pilot and pre-commercial manufacturing. This means that improving efficiencies remains a focal point of organic and dye solar cell R&D, to compensate for these losses in real use.

Surface area

The technique developed by Chaudhary and colleagues uses a substrate textured at the nano-level that allows deposition of an evenly thin light-absorbing layer over all the substrate's ridges.

The ridges increase the surface area of the solar cell for capturing light, including light reflected within the ridges. The cell maintains good electrical transport properties of a thin, uniform light-absorbing layer.

Similar approaches are already being used by the silicon solar cell industry. However, Chaudhary's team has managed to develop a process for organic solar cells, which has proved more challenging to do, with previous attempts failing to achieve a uniformly thin layer over all the ridges. Iowa State University is working on a strategy to license the technology to organic solar cell developers.

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