Over 20% conversion efficiency on silicon heterojunction solar cells by IPA-free substrate texturization

Amorphous/crystalline heterojunction (a-Si:H/c-Si) solar cells on n-type substrates, textured in isopropanol (IPA)-free solution, with conversion efficiencies exceeding 20% are presented. These values represent a considerable improvement over our previously reported best cell efficiencies for cells with (i)a-Si:H buffer layer. They were achieved by thorough optimization of the surface texture, of the a-Si:H/c-Si interface passivation, and of the thickness of the intrinsic a-Si:H front layer, resulting in improved open-circuit voltages and fill factors. Thus, solar cells fabricated on IPA-free textured Si wafers can compete with those processed on wafers textured conventionally in IPA-containing alkaline solution and are an attractive alternative for industrial production due to their better process control, lower environmental impact and lower costs.