Diffused bulk channels instead of laser drilled via-holes in emitter wrap-through solar cell structure: A simulation study

An emitter wrap-through solar cell structure with diffused channels instead of drilled via-holes has been proposed in this study. The proposed solar cell, with p-n junctions near the surface and in the bulk, is expected to perform better due to (i) zero shadow loss, (ii) enhanced carrier collection from bulk and (iii) low surface coverage of metal. The device structure is simulated in Synopsys® Sentaurus simulator and is compared to the conventional solar cell structure devoid of surface texture. Variation of solar cell performance due to variations in minority carrier lifetime, channel doping, channel diameter and inter-channel spacing has been studied. It is observed that the bulk minority carrier lifetime and separation between channels affect the performance of the cell more than other parameters. Simulation results show that when electron lifetime in p-type is 10 μs and hole lifetime in n-type is 3 μs, the proposed solar cell (with small pitch values) gives 17.5% efficiency while conventional solar cell gives 16.1% efficiency. When minority carrier lifetime in p-type is 100 μs, the proposed solar cell (with small pitch values) gives 19.2% efficiency.