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 RD 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 2500m Energy Research Labs at Imec 1000m silicon PV line in Leuven 1500m 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 m 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 m n-Cz Selective FSF Ag 100-150 m 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 m 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 m 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.PIETERSIMEC.BE TEL 32 16 281259 JOHNNY ZHU STRATEGIC PARTNERSHIP MANAGER CHINA JOHNNY.ZHUIMEC.CN TEL 81 1345 168 9012 CONTACT MONICA ALEMAN SENIOR SCIENTIST MONICA.ALEMANIMEC.BE