Light beam induced current and infrared thermography studies of multicrystalline silicon solar cells

Abstract

In this paper we demonstrate the parallel application of light beam induced current (LBIC) and lock-in infrared thermography for the investigation of strong shunting regions in multicrystalline silicon solar cells. Usually both mappings are not correlated, but in this case the shunts could be imaged by both techniques. If for a locally generated photocurrent the conductance through a shunt lying nearby is comparable to that across the emitter into the current amplifier, local shunts become visible in the LBIC as dark regions. After the rear contact of the cell was removed, the LBIC technique was performed from the rear side of the cell. The images point to the existence of inversion layers along grain boundaries crossing the bulk of the cell. Obviously, these inversion layers represent the dominant material-induced shunt type in multicrystalline silicon solar cells. Moreover, it has been shown that cracks may lead to shunts.