Transfer of the HIP-MWT solar cell concept to n-type silicon

First n-type Czochralski silicon (Cz-Si) metal wrap through (MWT) solar cells based on the high-performance MWT (HIP-MWT) concept are presented. Reference n-type H-pattern solar cells were processed in parallel. The MWT as well as the H-pattern cells with an edge length of 125 mm are completely metallized by screen printing. The fabricated n-type Cz-Si MWT solar cells achieved conversion efficiencies up to 17.7%. One of the main challenges for further development is to decrease the dark saturation current density j02 and to increase the shunt resistance RShunt above the current value of about 1 kΩcm2 The H-pattern reference cells also show similarly low RShunt as well as high j02 values and reach conversion efficiencies up to 17.1%. Thus the low RShunt and high j02 values cannot be attributed to the MWT concept. Specific contact resistances of about 8 mΩcm2 for front and rear metallization show the successful electrical contacting of the differently doped surfaces using sequential tube furnace diffusions. The advantage of less metallized front surface for the MWT cells compared to the H-pattern references is clearly visible in increased values for short-circuit current density and open-circuit voltage. With the results obtained, the feasibility of the transfer from p- to n-type Cz-Si is demonstrated