Low Temperature Deposition of Device-Quality Silicon Thin Films for Flexible PV Application

The present work demonstrates the fabrication of a-Si:H based thin film solar cells on Polyethylene naphthalate (PEN) flexible substrate using Hot-Wire CVD technique. The intrinsic a-Si:H thin films deposited at process temperature (TS) below 130°C with certain hydrogen dilution show a five order photoconductivity gain. The electronic Density of states (DOS) of these films have been investigated by Constant Photocurrent Method (CPM) which reveals a good correlation between H2 dilution of the silane gas during deposition, film microstructure and the electronic properties. Subsequently, p-i-n type solar cells were fabricated on PEN and glass substrates under similar deposition conditions of low TS and 40-50% H2 dilution. The solar cell deposited on PEN shows an efficiency of 5.7% while the simultaneously deposited cell on glass substrate shows an efficiency of 6%.