EPFL’s Institute of Microengineering(IMT) has achieved a 10.7% efficiency single-junction microcrystalline silicon solar cell, surpassing the previous world record of 10.1% held by the Japanese company Kaneka Corporation since 1998, according to the Swiss university.
This efficiency, independently certified by the Fraunhofer Institute for Solar Energy Systems, was achieved with less than 2 micrometers of photovoltaic active material.
The IMT Photovoltaics-Laboratory, founded in 1984 by Prof. Arvind Shah and now headed by Prof. Christophe Ballif, has pioneered the development of thin-film silicon solar cells, and the use of microcrystalline silicon as a photoactive material in thin-film silicon photovoltaic (TF-Si PV) devices.
Dr. Fanny Meillaud and Dr. Matthieu Despeisse led the team that achieved the 10.7% record efficiency.
The employed processes can be up-scaled to the module level, researchers say. While standard wafer-based crystalline silicon PV technology implements absorber layers with a thickness of about 180 micrometers for module conversion efficiency of 15-20%, 10.7% efficiency was reached here with 1.8 micrometers of silicon material, i.e. 100 times less material than for conventional technologies, and with cell fabrication temperature never exceeding 200°C.
Thin-film silicon technology offers the advantages of saving up on raw material and offering low energy payback time, thus allowing module production prices as low as 35 €/m2, reaching the price level of standard roof tiles.
Work leading to this result was supported by the Swiss Federal Office of Energy, the EU-FP7 program, the Swiss National Science Foundation and the Commission for Technology and Innovation.
