PassDop based on firing stable a-SiNx:P as a concept for the industrial implementation of n-Type PERL silicon solar cells

In this work, we present an approach to create a PERL structure for n-type silicon solar cells which is compatible with the high temperature step applied for firing of screen printed contacts. This approach is based on the PassDop concept presented by Suwito et. al. The PassDop approach combines a doped passivation layer with a laser process to create a local back surface field on the rear side. As the original PassDop layer-based on a-SiCx:P-is not firing stable, we developed a new layer based on phosphorous doped a-SiNx, the fPassDop layer. This layer provides a good passivation with an effective recombination velocity <5 cm/s after a firing step. For the local back surface field, a sheet resistance in the range of 60 O/sq was measured after applying the laser process. In a first batch, we applied this layer to small area solar cells achieving a conversion efficiency of 21.3 % (675 mV) with evaporated front contacts. As a proof of concept, we applied this layer to large area n-type solar cells with screen printed front side contacts achieving an efficiency of 20.1 % with a Voc of 668 mV.