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_∝=628 mV, J_sc=36.3 mA/cm², FF=76.8%, independently confirmed at FhG-ISE) have been obtained on Polix mc-Si on a solar cell area of 144 cm². The high J_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_∝ of 5-11 mV and in J_sc of 0.3-0.6 mA/cm², which were caused by an increase in the effective diffusion length of 40-50 μm. It has been demonstrated, that hydrogenation from a PECVD SiN_x layer applied to screen printed solar cells could be more effective than remote plasma hydrogenation in BCSCs.