N型双面大面积网板印刷

Large-area Screen-Printed Bifacial n-type Si Solar Cells M. Aleman, S. Singh, L. Tous, P. Choulat, I. Kuzma, F. Duerinckx, S. Jambaldinni, J. John, M. Recaman, I. Gordon, J.Szlufcik, J. Poortmans Industrial Forum, Shanghai, SNEC June 4th, 2019 PUBLIC Outline ▪ Introduction ▪ Experimental results – Rear-Junction cells – Front-Junction cells ▪ Summary & Outlook Introduction  1984, Belgium  Europe’s largest micro-electronics research center  583 million € revenue in 2018  4000 people  2 billion € infrastructure  CMOS pilot lines  PV pilot line  Battery labs PUBLIC PUBLIC Materials Cells Modules Systems Overview of Imec’s Silicon Solar Cell Development ▪ Our PV research builds on: – 35 years experience solar cell R&D with industrial oriented developments ▪ Eg: co-firing, i-PERC, MWT, AlOx passivation. – World class solar cell achievements in a state-of-the-art pre-pilot solar line 6 PUBLIC 2500m² Energy Research Labs at Imec 1000m² silicon PV line in Leuven 1500m² PV module, battery and TF-PV facilities in Genk Experimental Results 8 PUBLIC 5BB Bifacial Rear-Junction n-PERT Results presented at the SNEC 2018 5BB nPERT JSC (mA/cm2) VOC (mV) FF (%) Eta (%) average 40.0 ±0.1 685 ±0.2 80.0 ±0.2 22.0 ±0.1 Best cell 40.2 684.8 80.9 22.3*n-Cz Selective FSF passivation ARC SP Ag 5BB SP Al 5BB p++ AlSi p+ emitter J. Chen et al, SNEC, Shanghai, 2018 244.3 cm2 n-Cz from Longi, * confirmed by ISE Callab ▪ Benefits – High bifaciality ~90% (textured rear) – no LID, no PID in cooperation with: 9 PUBLIC Fine-Line Ag Printing ▪ Commercial Ag pastes & mesh screens ▪ Finger width ~30 µm (our current std), ~Ag: 100mg/cell for 12BB cell ▪ Finger width down to 75 Ω/sq Decouple passivated vs contacted areas J0, n++ region Passivated Metallized J0pass,n+ region n+ Ag 30-40 µm n-Cz Selective FSF Ag 100-150 µm n++ 11 PUBLIC Printed Bifacial Rear-Junction n-PERT ▪ Lower shading losses, minimized recombination, flat rear, Al paste, 12 busbars 12 World-record for large-area,2-side contacted cells without passivating contacts 244.3 cm2, ~ 5 Ωcm, 180 µm n-Cz-Si wafers from LongiP. Choulat, EUPVSEC Marseille 2019 * Independently confirmed by ISFH CalTec Latest results JSC (mA/cm2) VOC (mV) FF (%) Av. (12 cells) 40.2 692 82.7 Eta (%) Irev @ -12V (A) 23.0* 0.1 -0.4* 0.2 Best 40.3 693 83.1 23.2* -0.17* in cooperation with: Ag pad n-Cz Selective FSF passivation ARC SP Ag 12BB SP Al 12BB p++ AlSi p+ emitter PUBLIC Why Rear-Junction nPERT Cells? ▪ Cost calculation for 12BB bifacial cell (front vs rear-junction) Cost savings by use of Al instead of Ag for rear side metallization 13 Front emitter nPERT Rear emitter nPERT • Print Ag/Al front • Print Ag rear • Firing • Testing / sorting • Laser ablation rear • Print Ag front • Print Al finger rear • Print Ag pad rear • Firing • Testing / sorting Processes compared 4 $ct/wafer reduction mostly due to saving in consumables Rear Junction Front Junction PUBLIC L.Tous et al, SiPV, 2019 Colors indicate changes in grid design Simulation of Rear- and Front-Junction n-PERT cells Efficiency potential of 24.3% and 25.0% respectively 14 • Rear-Junction cells limited by collection probability of photo-generated carriers from short  • More effective implementation of poly-Si BSF for front emitter nPERT cells n-Si (mono) FE n-PERT SP-AgAl grid passivation Emitter BSF passivation SP-Ag grid PUBLIC Screen-printed Front-Emitter Boron-diffused n-PERT Bifacial Cells Strategy: ▪Test process flow as simple as possible: –Implementing best-known processes available in-house 15 PUBLIC Front-junction bifacial n-PERT cells ▪ Split Emitter – 1: Deep 120 W/sq – 2: Shallow 110 W/sq – 3: Deep 130 W/sq ▪ Split: front paste – 2 different commercial brands n-Cz n++ laser doped Al2O3 + SiOx/SiNy SP Ag fingers SP Ag fingers p+ BBr3 SiO2/SiNy n+ POCl3 Process flow SDR + texturing Boron diffusion BSG removal POCL diffusion (rear) n++ ns-UV laser doping PSG + mask removal Thermal oxidation Rear-side PECVD SiNx ALD Al2O3 front Front- PECVD SiOx/SiNx Screen-printing Firing Front mask (PECVD) Single-side rear-emitter etch Front-side SiO2 removal (HF dip) 16 PUBLIC 0BB Bifacial Front-Junction bifacial n-PERT 244.3 cm2 n-Cz from Longi, internal measurement 0BB FJ nPERT JSC (mA/cm2) VOC (mV) FF (%) Eta (%) Bifi (%) Best cell 40.8 679 79.4 22.0 96.3 ▪ Benefits – High efficiency potential – Bulk lifetime ▪ First run: 22.0% efficiency ▪ Voc up to 680mV ▪ Jsc : 40.8 mA/cm2 17 PUBLIC Results Front-junction Bifacial n-PERT ▪ 0BB cells ▪ Ag/Al front, Ag rear ▪ Process validated ▪ Further improvements identified: – Front metallization  FF, Voc – Optimize dielectrics  Jsc 18 D. 120 S. 110 Emitter [W/sq] D. 130 Summary & Outlook 19 PUBLIC Summary & outlook ▪ Highlights of progress made at imec with advanced metallization: 1. Fine line Ag fingers printing 30 µm wide with standard mesh screens 2. Optimization n++ laser doping process reducing J0pass ▪ Highlights of recent results – Bifacial rear-emitter nPERT on 244.3 cm2 wafer  23.2% – Bifacial front-emitter nPERT on 244.3 cm2 wafer  22.0% – Roadmaps for bifacial Front- and Rear- Junction nPERT efficiencies over 24% defined ▪ Outlook: – Continue development of the Front-Junction baseline – LPCVD/PECVD poly-Si passivating contacts (TOPCON) in pipeline – Imec can offer support to quickly achieve these efficiencies in production environment 20 PUBLIC Thank you for your attention! Thanks to The authors thank for funding part of this work for supplying materials used in this work www.imec.be PHILIP PIETERS BUSINESS DEVELOPMENT DIRECTOR PHILIP.PIETERS@IMEC.BE TEL: +32 16 281259 JOHNNY ZHU STRATEGIC PARTNERSHIP MANAGER CHINA JOHNNY.ZHU@IMEC.CN TEL: +81 1345 168 9012 CONTACT MONICA ALEMAN SENIOR SCIENTIST MONICA.ALEMAN@IMEC.BE