Optically-boosted planar IBC Solar Cells with Electrically-harmless Photonic Nanocoatings

Abstract Advanced light management via front-coated photonic nanostructures is a promising strategy to enhance photovoltaic efficiency through wave-optical light-trapping effects, avoiding the conventional texturing processes that induce the degradation of electrical performance due to increased carrier recombination. Here, TiO2 honeycomb arrays with different geometry were engineered through a highly-scalable colloidal lithography method on flat crystalline silicon (c-Si) wafers and tested on standard planar c-Si interdigitated back-contact solar cells (pIBCSCs). The photonic-structured wafers achieved an optical photocurrent of 36.6 mA/cm2, mainly due to a broad anti-reflection effect arising from the 693 nm thick nanostructured coatings; whereas the pIBCSC test devices reached 14% efficiency with 705 nm thick TiO2 nanostructures, which corresponds to ~30% efficiency gain relative to uncoated pIBCSCs. In addition, several designed structures showed unmatched angular acceptance enhancements in efficiency (up to 63% gain) and photocurrent density (up to 68% gain). The high-performing (yet electrically harmless) light-trapping scheme, here presented, entails a highly promising alternative to conventional texturing for c-Si technological improvement, with straightforward integration in the established photovoltaic industry.