Physics underlying improved efficiency of high-low-junction emitter silicon solar cells

This paper describes the physical behavior of a recently proposed device structure, the HLE solar cell [1], that yields substantial increases in the open-circuit voltage and in the power-conversion efficiency of p-n junction silicon solar cells. The structure differs from the conventional cell structure (n⁺-p) in that it contains a high-low (H-L) junction in the emitter (n⁺-n-p). For cells having low base resistivities (∼0.1 Ω-cm), efficiency improvements of about 15% at AM1 and about 40% at 50 suns can be expected. The improvement at 50 suns results in an efficiency of about 20% at 27°C.