Effectively surface-passivated aluminium-doped pR emitters for n-type silicon solar cells

Abstract

We present a detailed study on surface-passivated screenprinted aluminium-alloyed emitters for back junction n-type silicon solar cells. We investigated (i) two different commercially available aluminium pastes and (ii) two passivation layers both well suited for highly doped p + silicon: plasma-enhancedchemicalvapour-deposited amorphous silicon (a-Si) and atomic-layer-deposited aluminium oxide (Al 2O 3). We show that for the formation of a homogeneous, non-shunted emitter, a careful choice of the alloying conditions is essential. Moreover, for a most effective surface passivation, low emitter thicknesses have to be used. Combining these two aspects, we have achieved extraordinary high implied open-circuit voltages of 673mV for a-Si- and 685mV for Al 2O 3-passivated Al-alloyed emitters, corresponding to emitter saturation current densities of 128 and 55 fA/cm 2, respectively. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.