The pace of reaching the 30% efficiency goal for perovskite solar cells is speeding up. Belgium-based nanoelectronics, energy and digital technology developer Imec recently posted a conversion efficiency of 27.1% for a four-terminal perovskite-silicon tandem photovoltaic cell. This achievement has just been bested by University of Oxford (U.K.) spinout Oxford PV, with a 28% conversion efficiency certified by the National Source: Oxford PVSource: Oxford PVRenewable Energy Laboratory for a 1 cm2 perovskite-silicon tandem cell.

Solar cell performance is improved with a perovskite-structured hybrid organic-inorganic material incorporated as a light-harvesting active layer. Metal halide perovskites provide a high absorption coefficient when using ultrathin films of around 500 nm to absorb the complete visible solar spectrum.

Perovskite solar cells offer an advantage over traditional silicon solar cells in the simplicity of their processing. Traditional silicon cells require expensive, multistep processes conducted at elevated temperatures in a high vacuum in special clean-room facilities. The organic-inorganic perovskite material can be manufactured with simpler wet chemistry techniques in a traditional lab environment.

The company is now scaling its perovskite-silicon solar cell technology from the lab to high volume manufacturing. Oxford PV is also producing commercial sized 156 mm2 perovskite-silicon solar cells for validation by a development partner.

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