Large area multicrystalline silicon buried contact solar cells with bulk passivation and an efficiency of 17.5%

The purpose of this study was the development of a processing sequence for buried contact solar cells on multicrystalline silicon (mc-Si). The applied process includes mechanical V-texturing for the reduction of reflection losses as well as bulk passivation by a remote hydrogen plasma source. Record high efficiencies of 17.5% (V/sub /spl prop//=628 mV, J/sub sc/=36.3 mA/cm/sup 2/, FF=76.8%, independently confirmed at FhG-ISE) have been obtained on Polix mc-Si on a solar cell area of 144 cm/sup 2/. The high J/sub sc/ results from low shadowing and reflection losses, high bulk diffusion lengths and from a selective emitter structure. Hydrogenation was investigated for Baysix mc-Si and led to an increase in V/sub /spl prop// of 5-11 mV and in J/sub sc/ of 0.3-0.6 mA/cm/sup 2/, which were caused by an increase in the effective diffusion length of 40-50 /spl mu/m. It has been demonstrated, that hydrogenation from a PECVD SiN/sub x/ layer applied to screen printed solar cells could be more effective than remote plasma hydrogenation in BCSCs.