Process simplifications in large area hybrid silicon heterojunction solar cells

• Published in: Solar energy materials and solar cells 2015-11, Vol.142, p.66-74
• Main Authors: Tous, Loic, Granata, Stefano Nicola, Choulat, Patrick, Bearda, Twan, Michel, Alexis, Uruena, Angel, Cornagliotti, Emanuele, Aleman, Monica, Gehlhaar, Robert, Russell, Richard, Duerinckx, Filip, Szlufcik, Jozef
• Format: Article
• Language: English
• Subjects: Chromium; Contact; Copper; Crystalline silicon; Diffusion; Emitters; Heterojunction; Hybrid; n-Type; Nickel; Silver; Solar cell; Stacks
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2015.05.049

Recently, large area hybrid silicon heterojunction cells (SHJ) with nickel/copper (Ni/Cu) plated front contacts were shown to benefit from a simpler processing sequence than n-PERT cells featuring a boron diffused rear emitter. Hybrid refers here to the combination of a diffused front surface field (FSF) and a SHJ rear emitter. In this work, further process simplifications for such hybrid SHJ cells are evaluated. Based on reflectance and adhesion considerations, stacks of tin-doped indium oxide and copper (ITO/Cu) and chromium/silver (Cr/Ag) are tested as alternative to the previously chosen ITO/Ag rear contact stack. Using ITO/Cu/Al as rear contact stack, average efficiencies of 20.8±0.2% are presented on 6-inch wafers. We also demonstrate that the excimer laser annealing step previously employed to form nickel silicides at the front side can be skipped without comprising solder tab adhesion quality. •We report progress in the development of hybrid SHJ cells with Ni/Cu front contacts.•Various rear contact layers are tested as alternative to the commonly used ITO/Ag.•The impact of low temperature contact annealing on ITO properties is studied.•We show that NiSix formation can be skipped without compromising adhesion quality.•21.1% efficient cells are presented and results are compared to state-of-the-art n-PERT cells.