High efficiency n-type PERT and PERL solar cells

Abstract

n-type PERT and PERL structures both offer a high efficiency potential. In this work we applied ion implantation for the realization of both the emitter and the BSF of high-efficiency PERT and PERL structures and laser processes for local BSF formation showing efficiency benchmarks for those in principle industrially feasible technologies. For a fully ion implanted PERT solar cell we reached efficiencies up to 22.7%, showing that even at this high level no residual implantation damage is left and the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> is limited by the profiles themselves. For the PERL structure we applied the PassDop process using two different passivation layer systems (based on SiC <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ). With this laser based process we were able to reach conversion efficiencies up to 23.2%, showing that the laser doping process is as efficient as a PERL rear side realized by photolithography. To prove the industrial feasibility of these high-efficiency solar cell concepts we applied Ni plating as front side emitter metallization on a PassDop solar cell featuring a boron implanted emitter. For this cell type we were able to reach an efficiency of 21.7% in a first prove of principle batch.