High-efficiency silicon solar cells: Development, current issues and future directions

Abstract

This paper provides a review of material, process and design considerations that are essential for achieving high-efficiency silicon solar cells. It describes an approach that resulted in 18.0–18.5% efficient cells on low-resistivity float-zone silicon material. Through design, fabrication and analysis of these 18.0–18.5% efficient cells, the importance of the back-surface field, surface passivation, efficient anti-reflection coating, reduced heavy doping, reduced contact recombination and back-surface reflector are emphasized. It has been shown experimentally that a combination of surface passivation and double-layer anti-reflection coating can provide 2–3% (absolute) improvement in cell efficiency provided the material, process and cell design are carefully selected. Experimentally observed improvements in cell efficiency are supported by model calculations and, on that basis, an approach to ⩾ 20% efficient cells is outlined.