Selective Emitters in Passivated Emitter and Rear Silicon Solar Cells Enabling 20% on Large Area p-Type Silicon

Abstract

We present a comparison of solar cells featuring homogeneous and selective emitters on devices with passivated surfaces. Solar cells are fabricated on high quality float zone silicon and commercial Czochralski grown silicon substrates. Three different emitter structures are compared, two homogenous ones and one selective emitter. The surfaces are passivated by a thin thermal oxide. The cells feature screen printed metallization and laser fired point contacts on the rear side. Higher conversion efficiencies are found for the cells with a selective emitter. A gain in the open circuit voltage of up to 1.3% is observed for the cells on FZ-Si. This advantage is smaller on the Cz-Si substrates and the recombination active boron oxygen complex further reduces the profit of the selective emitter in fill factor, open circuit voltage and thus conversion efficiency.