Enhanced rear-side reflection and firing-stable surface passivation of silicon solar cells with capping polymer films

Abstract

Low refractive index polymer materials have been investigated with a view to form the back surface mirror of advanced silicon solar cells. SiOx:H or AlOy SiOx:H polymer films were spun on top of an ultra-thin (<10 nm) atomic-layer-deposited (ALD) Al2O3 layer, itself deposited on low-resistivity (1 Ω cm) p-type crystalline silicon wafers. These double-layer stacks were compared to both ALD Al2O3 single layers and ALD Al2O3/plasma-enhanced chemical vapour deposited (PECVD) SiNx stacks, in terms of surface passivation, firing stability and rear-side reflection. Very low surface recombination velocity (SRV) values approaching 3 cm/s were achieved with ALD Al2O3 layers in the 4-8 nm range. Whilst..