Fraunhofer ISE-Maximilian POSPISCHIL

Fraunhofer ISE ; FHG- SK INTERNAL CONFIDENTIAL Additional Applications around the PV Back-End DISPENSING 0,5 → Increased Bifaciality ◼ Al Fire Through Al-FT Pastes[1, 2] potentially replacing → LCO p-PERC → AgAl n-PERT Challenges ◼ Contact necking required to prevent parasitic etching ◼ Conductivity of Al pastes [1] E. Navarrete Astorga et al., 10th Spanish Conference on Electron Devices CDE, 2015 [2] T. Fellmeth et al. , 8th Silicon PV 2019 43m Non Fire Through Al Fire Through Al Fraunhofer ISE 10 , 2017 All Dispensed Mini Module Dispensed Interconnection ◼ Dispensing of bus line edges during cell production ◼ Dispensing of conductive adhesive between front and rear bus lines for interconnection Dispensed glue at module level between dispensed bus line edges from cell production Application of Ag- coated and structured ribbons Fraunhofer ISE 11 , 2017 All Dispensed Mini Module Dispensed Interconnection ◼ Dispensing of bus line edges during cell production ◼ Dispensing of conductive adhesive between front and rear bus lines for interconnection Process flow one cell module ◼ Four dispensing steps on cell level ◼ Two additional on module level → No screen printing, no laser Results at interconnected level → All-dispensed interconnected bifacial cell demonstrated FF Vmpp V Impp A Pmpp W 77.5 0.545 8.60 4.68 Fraunhofer ISE 12 , 2017 Parallel Dispensing Approaching Different Applications in Si PV Paste supply Wafer movementp-PERC, Front Side Ag Bifacial PERC, Rear Side Al, Al-FT n- PERT, FS AgAl, AL-FT FS- Print RS- Print HJT, low temp. Ag, AgCu BB- Print Fraunhofer ISE 13 , 2017 Al-FT vs. AgAl Pimping the BiSoN, IV results ◼ Dispensing and screen printing of AgAl pastes ◼ Jsc Al-FT group with D60m contacts ◼ Voc on high level → BSF Nf,D 100 Nf,SP 120 Mihailetchi et al. bifiPV workshop, Chambery, 2014 Δ𝑉𝑜𝑐 𝐽𝑠𝑐 VT Δ𝐽𝑠𝑐𝐽 𝑠𝑐 Fraunhofer ISE 14 , 2017 Al-FT vs. AgAl Pimping the BiSoN, FF analysis ◼ Dispensing and screen printing of AgAl pastes ◼ Jsc Al-FT group with D60m contacts ◼ Voc on high level → BSF Challenge ◼ Still low Al-FT line resistivity Nf,D 100 Nf,SP 120 FT-Al ≈ 40cm Fraunhofer ISE 15 , 2017 Parallel Dispensing Approaching Different Applications in Si PV Paste supply Wafer movementp-PERC, Front Side Ag Bifacial PERC, Rear Side Al, Al-FT n- PERT, FS AgAl, AL-FT FS- Print RS- Print HJT, low temp. Ag, AgCu BB- Print Fraunhofer ISE 16 , 2017 HJT Low Temperature Paste Evaluation Recent Activities and Challenges Motivation for intense activities ◼ Ag reduction and throughput potential ◼ BB-less, bifacial application ◼ Suitable for many future cell concepts ◼ Temperature sensitive pastes ideal for closed system applications Challenges ◼ Die Swell in polymer extrusion Polymers tend to retain their initial structure after being forced through small openings ◼ ITO with reduced pinning effects ◼ Paste rheology not yet ideal for dispensing Latest contact on ITO, dispensed with D 35m opening 48m Fraunhofer ISE 17 , 2017 HJT Application Dispensing Front and Rear Grid Paste evaluation on industrial precursors, IV results ◼ SP groups only to indicate eta potential 5BB ◼ Still higher efficiency level of Ag pastes compared to AgCu ◼ First paste to be dispensed with D35m → SP level reached at lower ΔmAg ΔmAg 2 x 65mg ΔmAg 65mg120mg Lower wf Fraunhofer ISE 18 , 2017 Parallel Dispensing on Front and Rear Side Summary Outlook ◼ Results on PERC max 21.9 reached ◼ Record contacts with excellent contacting behaviour wf 17m hf 14m ◼ Rear Side Activities for Bifacial PERC with Al-FT ◼ Necking required to prevent parasitic etching ◼ First all dispensed mini module demonstrated ◼ n-PERT Challenging AgAl with Al-FT ◼ Voc gap closing, FF requires better conductivity ◼ HJT Applying low temperature curing pastes ◼ Sucessfull application of Ag and AgCu pastes ◼ Sucessfull manufacturing of all dispensed cell with max 22.2, SP level reached 43m 17m Fraunhofer ISE 19 , 2017 Thank you for your attention We will be back ☺ Fraunhofer-Institute for Solar Energy Systems ISE Dr.-Ing. Maximilian Pospischil www.ise.fraunhofer.de maximilian.pospischilise.fraunhofer.de Fraunhofer ISE 20 , 2017 Pictures to Remember dispensed lines wf 17m, hf 14m ☺ ◼ Commercial available screen printing paste, dispensed with 20m nozzle ◼ Stable processing for 45min., solar cells with N150 fingers, mAg 45mg → We are not yet at the limit and haven‘t started commercialization yet