Trina Solar - Yifeng Chen
© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 1 Passivated contacts: the path to 25% large-area industrial crystalline silicon solar cells Yifeng Chen, Yang Yang, Daming Chen, Xueling Zhang, Guanchao Xu, Pietro P. Altermatt, Zhiqiang Feng, Pierre Verlinden State Key Lab of PV Science and Technology, Trina Solar Corresponding: yifeng.chen01@trinasolar.com PVCELLTECH conference 12-13 March 2019, Penang, Malaysia © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 2© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 2 Overview of current champion Lab cells HJT (25.1%, Kaneka 2015) IBC (25.2%, SunPower 2015) PERL (25%, UNSW 2001) [1] Zhao et al., SOMAT, P429, 2001 [2] Smith et al., IEEE PVSEC, 2014 [3] Adachi et al., APL 233506, 2015 [4] Richter et al., SOLMAT, P96, 2017 TOPCon (25.8%, Fraunhofer 2017) © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 3© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 3 Overview of current champion Lab cells HJT (25.1%, Kaneka 2015) IBC (25.2%, SunPower 2015) PERL (25%, UNSW 2001) [1] Zhao et al., SOMAT, P429, 2001 [2] Smith et al., IEEE PVSEC, 2014 [3] Adachi et al., APL 233506, 2015 [4] Richter et al., SOLMAT, P96, 2017 TOPCon (25.8%, Fraunhofer 2017) Hetero IBC (26.7%, Kaneka 2017) Passivated contact IBC (26.1%, ISFH 2018) [5] Yoshikawa et al., Nat Energy, 17032, 2017 [6] ISFH, 2018 One way to have innovation is to go across the “boundary”. © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 4© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 4 Overview of current champion Lab cells HJT (25.1%, Kaneka 2015) IBC (25.2%, SunPower 2015) PERL (25%, UNSW 2001) [1] Zhao et al., SOMAT, P429, 2001 [2] Smith et al., IEEE PVSEC, 2014 [3] Adachi et al., APL 233506, 2015 [4] Richter et al., SOLMAT, P96, 2017 TOPCon (25.8%, Fraunhofer 2017) Hetero IBC (26.7%, Kaneka 2017) Passivated contact IBC (26.1%, ISFH 2018) [5] Yoshikawa et al., Nat Energy, 17032, 2017 [6] ISFH, 2018 ? Passivated contact PERX ? Heterojunction PERX Low cost © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 5© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 5 Overview of current champion Lab cells HJT (25.1%, Kaneka 2015) IBC (25.2%, SunPower 2015) PERL (25%, UNSW 2001) [1] Zhao et al., SOMAT, P429, 2001 [2] Smith et al., IEEE PVSEC, 2014 [3] Adachi et al., APL 233506, 2015 [4] Richter et al., SOLMAT, P96, 2017 TOPCon (25.8%, Fraunhofer 2017) Hetero IBC (26.7%, Kaneka 2017) Passivated contact IBC (26.1%, ISFH 2018) ? Passivated contact PERX ? Heterojunction PERX Low cost“Efficiency drops by ~1% abs. from champion cell to production [7]” [5] Yoshikawa et al., Nat Energy, 17032, 2017 [6] ISFH, 2018 [7] Verlinden et al., PVSEC 26, 2016 © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 6© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 6 HJT (25.1%, 24.1%, 2015) IBC (25%, 24%, 2014) PERL (25%, 24%, 2001) TOPCon (25.8%, 24.8%, 2017) Overview of current champion Lab mass-produced cells [5] Yoshikawa et al., Nat Energy, 17032, 2017 [6] ISFH, 2018 [7] Verlinden et al., PVSEC 26, 2016 [1] Zhao et al., SOMAT, P429, 2001 [2] Smith et al., IEEE PVSEC, 2014 [3] Adachi et al., APL 233506, 2015 [4] Richter et al., SOLMAT, P96, 2017 HIBC (26.7%, 25.7%, 2017) Passivated contact IBC (26.1%, 25.1%, 2018) ? Passivated contact PERX ? Heterojunction PERX IBC: 0% front contact shading front/rear contact: ~5% of front contact shading)Passivatedcontact PERX + Bifacial © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 7 The development of TOPCon J0e,pass = 11-15 fA/cm²J0e,metal = 200 fA/cm² TOPCon: J0,cont 7 fA/cm² n-Si, W = 200 µm p++ Tunnel oxide n-Si Base Amorphous/Polycryst. Si (n)-Layer EC EF EV Ultrathin tunnel oxide using HNO3 Polysilicon by PECVD 800 °C annealing Jo, TOPCON = 4 fA/cm2 Full-area rear contact with evaporated Ag The first idea of SiOx/poly-Si was introduced from semiconductor in 1980s, like SIPOS [1] Later study in Stanford University [4] and SunPower [8] Research topic [5-9] in: FhG-ISE, ISFH, ECN, EPFL, ANU, Georgia Tech, NREL, SYSU, Delft Uni, UNSW Tunnel Oxide Passivated Contact from Fraunhofer [7] [1] T. Matsushita et al., JJAP 20 (1981) 75 [2] E. Yablonovitch et al., APL 47 (1985) 1211. [3] Y. Kwark et al., SIPOS heterojunction contacts, 1986 [4] Gan and Swanson, IEEE PVSC (1990) [5] F. Feldmann et al., EU PVSEC (2013) [6] F. Feldmann et al., SolMat (2014) [7] A. Richter, et al., SOLMAT, 2017 [8] Smith et al., IEEE PVSEC, 2014 [9] U. Roemer et al., SolMat (2014) © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 8© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 8 The comparison of poly Si and a-Si passivation Poly Si a-Si Passivation structure thin SiOx/poly-Si (n+/p+) a-Si:H (i)/a-Si:H (n/p) Passivation effect [1] J0,e = 2.7 fA/cm2 (n) J 0,h = 16 fA/cm2 (p) J0,e = 2 fA/cm2 (n) J0,h = 2 fA/cm2 (p) Typical cell structure / Best Lab eff TOPCon 25.7% (FhG-ISE) HIT 25.1% (Kaneka) Features High temp. Good Jsc Relative low Voc Good FF Low temp. Low Jsc (TCO/a-Si abs.) Good Voc Relative low FF (TCO) To today’s PV industry Evolutionary Relative low capex RevolutionaryHigh capex Industry status This work Med cell eff 23.3% (Meyer Burger) Med. Mod. eff 19.4% (325W) Panasonic [1] J. Schmidt et al., SOLMAT 187 (2018) 39 © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 9© 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 9 Excellent experiment passivation result with SiOx/poly Study since 2015 5 Ωcm n-type Cz wafer 1.5nm SiOx/ in-situ poly (n+) by LPCVD Passivated by SiNx:H Excellent passivation increase tp to 36 ms J0 700mV Front η 23% i-TOPCon cell by Trina solar Passivation stacks © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 14 Industrial tunnel oxide passivated contact (i-TOPCon) cell Lab development Independently confirmed by JET, 2018 Lab development started in 2015 Frist patent in Aug 2015 Investigations on n-type, and p-type poly 2018: Industrial n-type Cz wafer 23.1% (F) and 17.9% (R) efficiency demonstrated in (JET) Voc up to 708.6 mV 2019 24.1% (F) efficiency (SKL in-house measurement) Voc up to 717.2 mV © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 15 Industrial tunnel oxide passivated contact (i-TOPCon) cell High Eff. cells Wafer quality control Cleanness of environment and facilities Good design of cell structure Fine tune of processing parameters Good control of production operation Stability of equipment Contamination control is critical! The path to industrialization of i-TOPCon © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 16 Industrial tunnel oxide passivated contact (i-TOPCon) cell i-TOPCon cells in mass production with 23% efficiency in Trina solar 25% large-area IBC cell with contact passivation Demonstration of best laboratory i-TOPCon bifacial cell with 24.1% efficiency First demonstration of mass produced i-TOPCon cell with median eff. 23% (~1% below champion Lab cell) Our i-TOPCon cell combine the advantage of PERC (relative low cost) and TOPCon (high efficiency). © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 208 About Trina Solar Trina Solar is a leading global total solutions provider for solar energy. Founded in 1997, Trina Solar has expanded its business into more than 100 countries and regions. Trina Solar develops photovoltaic modules, energy storage systems, smart systems and O&M, and provides clients with proprietary system integration solutions for project development, financing, design, and construction. By the end of 2017, Trina Solar had shipped more than 30 GW of photovoltaic modules worldwide and had connected 2 GW of solar projects to the grid across the globe. In 2018, the company launched Trina IoT, a brand of energy Internet of Things, and is committed to becoming a global leader in this field. For more information, please visit www.trinasolar.com. © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 21 The State Key Lab of PV Science & Technology Applied 1376 patents Granted patents 795 100 papers Patents Over 50 government funded projects 2 national 973 projects 5 national 863 projects R&D projects International top scientists team 18 records on cell efficiency and module power Initiated R&D and industrialization of PERC in China First Industrial large-area 25% IBC cell Leading industrialization of i-TOPCon Technology innovations © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 22 Acknowledgements Many thanks to: the national technology TOP RUNNER project, the colleagues in SKL and Trina solar, the partners in PV community! © 2017 Trina Solar. All rights reserved. CONFIDENTIAL. 23
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