Low Temperature Deposition of Amorphous Silicon Based Solar Cells

Abstract

AbstractOur investigations study the influence of various deposition parameters on the structural and optoelectronic properties of a-Si:H deposited at temperatures of 100 °C and below. Despite a significant material quality deterioration at low substrate temperatures, we observe remarkable improvements of charge carrier transport properties due to an increased H2-dilution of the process gases. In case of doped layers, we restore the electrical conductivity of low temperature n-type a-Si:H to standard values, whereas the p-layer quality is still inferior. We incorporate our optimized low temperature layers into a variety of solar cell types, including single and tandem cell structures. In addition to our conventional pin-structures we also successfully develop nip-cells for growth on opaque polymer substrates. From pinpin tandem cells, we record initial efficiencies of 6.0 % at a deposition temperature of 100 °C and 3.8 % at 75 °C. Interestingly, our nipnip tandem structures attain similar values which offers the possibility for deposition on low-cost plastic substrates. The mechanical flexibility of such substrates offers a wide variety of novel applications.