Polymeric amorphous carbon as p-type window within amorphous silicon solar cells

Abstract

Amorphous carbon (a-C) has been shown to be intrinsically p-type, and polymeric a-C ~PAC! possesses a wide Tauc band gap of 2.6 eV. We have replaced the p-type amorphous silicon carbide layer of a standard amorphous silicon solar cell with an intrinsic ultrathin layer of PAC. The thickness of the p layer had to be reduced from 9 to 2.5 nm in order to ensure sufficient conduction through the PAC film. Although the resulting external parameters suggest a decrease in the device efficiency from 9.2% to 3.8% due to a reduced value of open-circuit voltage, the spectral response shows an improvement in the 400–500-nm wavelength range, as a consequence of the wider band gap of the PAC layer.

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