DuPont Solamet Next Generation Front Side Silver Paste Development

Transcription

1 DuPont Solamet Next Generation Front Side Silver Paste Development PV Taiwan, 2017 Ryan Lin, Application Technical Group, DuPont Photovoltaic Solutions

2 Efficiency Entitlement Technical Challenges from metallization paste s point of view: - Line-width control - Finger line resistance (aspect ratio and bulk resistivity) - Contact resistance - Long term printability Advanced screen technologies (MCF, fine wire) Higher Laydown 20X ~0.1% DEff 19B Lower Efficiency *Assuming PV19B solids, resistivity, using a screen F. Lemmi & D. Inns, DuPont SVTC Solamet Modeling Indicates 0.05~0.1% Entitlement by Ultra Fine Line Copyright All rights reserved. 2

3 Efficiency by Finer Screen Opening Aspect ratio vs. Finger opening DuPont Solamet PV20x demonstrate better aspect ratio while moving to finer line opening design (inner) 3

4 NCell 19.54% 19.50% 19.62% 19.56% Efficiency by Finer Screen Opening DuPont Solamet PV20x performance with finer opening 0.05 ~ 0.1% Efficiency gain demonstrated. Higher Isc without FF drop while moving to finer line 19.80% 19.60% 19.40% screen opening Paste Next Gen FS PV19B Wafer : 6 M2 Mono 90 ohm/sq Paste Screen Eff Voc Isc FF Rs PV20x um-110F PV20x um-105F PV20x um-105F PV19B um-105F Ref Note: Screen opening is narrow side. 4

5 DuPont Solamer PV20x Adhesion Performance Adhesion performance Solamet PV20x shows strong peel-off force on both conventional multi wafer and diamond wire saw wafer. 5

6 Efficiency Entitlement Efficiency entitlements from FS silver 0.1% by 10um narrower lines 0.3% by reduced recombination (J 0,e & J 0,m ) while maintaining contact 0.3% by reduced BSF recombination through lower firing temp. 6

7 Efficiency Benefit by Light Doping Emitter Recombination reduction on PERC mono cells Eff. benefit from high R sheet emitter *Assuming bulk lifetime is 300us metallization at 885C Why Voc was not increased linearly?? Rsheet increase from Ω/sq generate 0.24% Eff. Rsheet below 115 Ω/sq to form good contact. 7

8 After Metallization Before Metallization Efficiency Benefit by Light Doping Emitter Voc performance before & after metallization Metal recombination (J 0,m )is playing more important role when moving to lighter doping emitter 8

9 Efficiency Benefit by Light Doping Emitter Impact of saturation current density, J 0 While emitter recombination improves with less doping, metal recombination gets worse. Paste must find best compromise The opposite emitter requirements for Joe & Jom drives desire for selective emitter Surface recombination velocity of highly doped ntype silicon Andrés Cuevas, Paul A. Basore, Gaëlle GiroultMatlakowski, and Christiane Dubois Citation: J. Appl. Phys. 80, 3370 (1996); doi: /

10 Measurement of J 0,m J 0 Data regression Calculate J 0 from ideal diode equation J 0 = J sc / exp { ( Voc / n. Vt) 1 } Vt = 25.88mV (physical constant) Assume ideality factor n =1, so J0 is actually J0,1 Shading Area - Slope = J 0,metal - Interception = J 0,emitter 10

11 Measurement of J 0,m Test conditions for J 0,m study 2 different wafer sources (different diffusion) were selected to understand what the impact on metal-induced recombination Diffusion Surface [ P ] Remark A 1.0E+19 ~ 7.0E+19 Aggressive LDE B 2.0E+20 ~ 5.0E+20 Std LDE 11

12 J 0,m Performance Impact of J 0,m of different inorganic system Different inorganic chemistry will results totally different metel-induce saturated current results Paste #1 J 0,m = 660 ~ 826fA/cm 2 J 0,e = 130 ~ 144 fa/cm 2 Paste #2 J 0,m = 213 ~ 305 fa/m 2 J 0,e = 130 ~ 141 fa/cm 2 12

13 J 0,m Performance Impact of J 0,m of different inorganic system Different diffusion will results totally different metel-induce saturated current results Wafer A J 0,m = 660 ~ 826fA/cm 2 J 0,e = 130 ~ 144 fa/cm 2 Wafer B J 0,m = 366~412 fa/cm 2 J 0,e = 149 ~ 168 fa/cm 2 13

14 Next Generation Inorganic Performance Voc performance on difference diffusion wafer The next gen. frit give better Voc performance on all the diffusion approach. Meanwhile, it also give wider window when moving to lighter diffusion. 14

15 Next Generation Inorganic Performance IV performance on difference diffusion wafer The next gen. frit give better Voc & Isc performance with comparable FF performance, then demonstrates more than 1% eff. benefit. 15

16 Solar Cell Efficiency Evolution Copyright All rights reserved. 16

17 Conclusion Solamet PV20x shows strong performance on fine line printability and good peel-off force, including DWS multi wafer Metal-induce recombination J 0,m is playing more important role when moving to lighter doping emitter / high Rsheet. DuPont Solamet next generation front silver enable to achieve >0.1% eff. gain by fineline and diffusion optimization via Isc and Voc improvement respectively while maintaining FF and Jom. 17

18 photovoltaics.dupont.com.cn Copyright 2017 DuPont or its affiliates. All rights reserved. The DuPont Oval Logo, DuPont, The miracles of science and all products denoted with or are registered trademarks or trademarks of E. I. du Pont de Nemours and Company or its affiliates. Images reproduced by E. I. du Pont de Nemours and Company under license from the National Geographic Society. Copyright All rights reserved. 18