Details

Autor(en) / Beteiligte

• Baker-Finch, Simeon C.
• McIntosh, Keith R.

Titel

One-dimensional photogeneration profiles in silicon solar cells with pyramidal texture

Ist Teil von

• Progress in photovoltaics, 2012-01, Vol.20 (1), p.51-61

Ort / Verlag

Chichester, UK: John Wiley & Sons, Ltd

Erscheinungsjahr

2012

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• ABSTRACT The key metric of surface texturing is the short‐circuit current Jsc. It depends on front surface transmittance, light trapping and the spatial profiles of photogeneration G and collection efficiency ηc. To take advantage of a one‐dimensional profile of ηc(ζ), where ζ is the shortest distance to the p–n junction, we determine G(ζ) via ray tracing. This permits rigorous optical assessment of common pyramidal textures for various cell designs. When ζ is small, G(ζ) is largest beneath regular inverted pyramids, upright pyramids (regular or random) and planar surfaces, respectively. This higher G(ζ) results in superior collection of generated carriers in front‐junction cells. In simulations of a conventional screen‐print cell, 92.0% of generated carriers are collected for inverted pyramids, compared to 91.4% for upright pyramids, and 90.0% for a planar surface. Higher efficiency and rear junction devices are analysed in the paper. Despite differences in G(ζ) beneath textures, inverted pyramids achieve the highest Jsc for all cell designs examined (marginally so for high‐efficiency rear‐contact cells) due to superior front surface transmittance and light trapping. We assess a common one‐dimensional model for photogeneration beneath textured surfaces. This model underestimates G(ζ) when ζ is small, and overestimates G(ζ) when ζ is large. As a result, the generation current determined is inaccurate for thin substrates. It can be computed to within 3% error for 250 µm thick substrates. However, errors in G(ζ) can lead to 7.5% inaccuracy in calculations of Jsc. Errors are largest for lower efficiency designs, in which collection efficiency varies through the substrate. Copyright © 2011 John Wiley & Sons, Ltd. We determine one‐dimensional photogeneration profiles as a function of the distance to the front surface beneath various pyramidal textures via ray tracing. Certain compatabilities between surface morphology and cell design are quantified when the pyramidal texture drives photogeneration into regions of favourable collection efficiency. Finally, we assess a common one‐dimensional model for photogeneration beneath textured surfaces, finding that its deficiencies compromise device simulation when collection efficiency varies strongly across the device.