Improving the built-in potential of p-i-n amorphous silicon solar cells

In order to increase the built-in voltage of hydrogenated amorphous silicon solar cells, in this work we exploit the use of very thin (<5 nm) high conductivity layers at the interfaces between the electrodes and the doped regions of an amorphous silicon n-i-p stacked structure. The idea starts from results of experiments showing that very thin chromium silicide layers, formed at room temperature after evaporation of chromium on amorphous silicon doped films, are able to reduce the activation energy to few meV in both kind of doped layers. The detailed structure of the proposed device is: glass substrate/bottom electrode/chromium silicide/n-type-intrinsic-p-type amorphous silicon layers/chromium silicide/top electrode. Simulation results obtained by a numerical device description and measurements of the current-voltage characteristic under AM1.5G illumination condition, together with quantum efficiency curve, demonstrate the built-in potential enhancement of the proposed solar cell structure with respect to identical structure without any chromium silicide layer. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.