CAPACITANCE EFFECTS IN HIGH-EFFICIENCY CELLS

Frequently transient measurement techniques lead to capacitance effect s which complicate the accurate measurement of the performance of high efficiency solar cells. The photo-current-response measurement (PCR), developed at ESTI, offers a tool for the investigation of these capac itance effects. This paper describes the theory of capacitance effects and the diffusion capacitance as experimental results achieved by the PCR-method. The theory shows that the diffusion capacitance is strong ly dependent on the minority carrier diffusion length and lifetime. In the future the PCR-method could be used for the determination of this solar cell parameter. We show, using monochromatic light pulses, that the induced diffusion capacitance charge (Q(diff)) is exponentially d ependent on the bias voltage and linearly dependent on the light inten sity. Finally, the capacitance effect is made clearly visible by the g eneration of the current-voltage characteristic from PCR-measurements.