Intensity effects in SnO2—Si heterojunction solar cells

The saturated photocurrent of SnO2-n-Si heterojunction solar cells is found to be linear with illumination intensity up to 30 suns of simulated AM1 irradiation. An interfacial layer at the SnO2-Si junction causes the open-circuit voltage to saturate at a value of light intensity determined by the thickness of this layer. The resistance of this interfacial layer limits the fill factor of these devices. It is shown that the open-circuit voltage depends on an internal diode quality factor rather than on that measured from the terminal characteristics. The internal diode quality factor can be determined from measurements of open-circuit voltage and saturated photocurrent, with illumination intensity as a parameter.