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

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. © 2003 American Institute of Physics. @DOI: 10.1063/1.1580636#