Electrical contacts on polyimide substrates for flexible thin film photovoltaic devices

Both frontal and back electrical contacts have been developed onto polyimide sheets (Kapton KJ(R)) as alternative substrates to the conventional glasses, for application in lightweight and flexible thin film photovoltaic devices. Transparent and conductive indium tin oxide (ITO) thin films have been deposited by r.f.-magnetron sputtering as the frontal electrical contact. On the other hand, Mo, Cr and Ni layers have been prepared by e-gun evaporation for the back electrical connections. ITO films deposited onto polyimide have shown similar optical transmittance and higher electrical conductivity than onto glass substrates. The transmittance decreases and the conductivity increases after heating at 400 degreesC in vacuum atmosphere. Mo, Cr and Ni layers deposited onto polyimide showed similar structure and electrical conductivity than onto conventional glasses. The properties of Mo and Cr layers remained unchanged after heating at 400 degreesC in selenium atmosphere. (C) 2003 Elsevier Science B.V. All rights reserved.