Heterojunction Interdigitated Back-Contact Solar Cells Fabricated on Wafer Bonded to Glass

Future wafer-based silicon solar cells will be fabricated on thin (<;140 μm) wafers. However, technologies to handle thin wafers during cell processing are not yet available for industry. In this paper, a flow to handle thin wafers during rear side cell processing is developed and demonstrated on 4-in 200 μm-thick wafers. The flow involves bonding the wafers to glass after front-side processing followed by a low-temperature p-n heterojunction formation on the rear side. 2.5 × 2.5 cm2 amorphous/crystalline silicon heterojunction interdigitated back-contact solar cells are fabricated by use of lithography while bonded to glass, and they show an efficiency of up to 17.7%. Shunts, infrared light absorption, and rear side interface passivation are identified as the main efficiency losses. Dedicated experiments suggest that the passivation losses are related to the degradation of the adhesive during wafer cleaning. Hence, methods to improve the compatibility of the adhesive with the cleaning process are discussed.

[1]  D. A. Clugston,et al.  Crystalline silicon on glass (CSG) thin-film solar cell modules , 2004 .

[2]  B. Rech,et al.  Efficient interdigitated back‐contacted silicon heterojunction solar cells , 2011 .

[3]  Martin A. Green,et al.  Solar cell fill factors: General graph and empirical expressions , 1981 .

[4]  M. Meuris,et al.  18% Efficiency IBC Cell With Rear-Surface Processed on Quartz , 2013, IEEE Journal of Photovoltaics.

[5]  F. Granek,et al.  Shading effects in back-junction back-contacted silicon solar cells , 2008, 2008 33rd IEEE Photovoltaic Specialists Conference.

[6]  Module interconnection of both sides-contacted silicon solar cells by screen-printing , 2013, 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC).

[7]  C. Ballif,et al.  Improvement of the open circuit voltage by modifying the transparent indium–tin oxide front electrode in amorphous n–i–p solar cells , 2012 .

[8]  C. Ballif,et al.  Improved amorphous/crystalline silicon interface passivation by hydrogen plasma treatment , 2011 .

[9]  Jef Poortmans,et al.  Development of a-Si:H/c-Si heterojunctions for the i2-module concept: Low-temperature passivation and emitter formation on wafers bonded to glass , 2013 .

[10]  M. Hermle,et al.  New concepts for silicon solar cells , 2009, 2009 13th European Conference on Power Electronics and Applications.

[11]  R. Street,et al.  Defects in bombarded amorphous silicon , 1979 .

[12]  L. Korte,et al.  Effect of wet-chemical substrate pretreatment on electronic interface properties and recombination losses of a -Si:H/c -Si and a -SiNx:H/c -Si hetero-interfaces , 2011 .

[13]  M. Taguchi,et al.  24.7% Record Efficiency HIT Solar Cell on Thin Silicon Wafer , 2013, IEEE Journal of Photovoltaics.

[14]  Ajeet Rohatgi,et al.  Rapid and Accurate Determination of Series Resistance and Fill Factor Losses in Industrial Silicon Solar Cells , 2001 .

[15]  Jan Vanfleteren,et al.  A Novel Concept for Advanced Modules with Back-Contact Solar Cells , 2010 .

[16]  D. N. Wright,et al.  Qualification of encapsulation materials for module-level-processing , 2014 .

[17]  G. Chen,et al.  Optimized Wet Processes and PECVD for High-Efficiency Solar Cells , 2012 .

[18]  C. Ballif,et al.  High-efficiency Silicon Heterojunction Solar Cells: A Review , 2012 .

[19]  T. Bearda,et al.  High-quality epitaxial foils, obtained by a layer transfer process, for integration in back-contacted solar cells processed on glass , 2012, 2012 38th IEEE Photovoltaic Specialists Conference.

[20]  Christophe Ballif,et al.  Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells , 2013 .

[21]  P. Kapur,et al.  A Manufacturable, Non-Plated, Non-Ag Metallization Based 20.44% Efficient, 243cm2 Area, Back Contacted Solar Cell on 40um Thick Mono-Crystalline Silicon , 2013 .

[22]  Robert Mertens,et al.  Plasma–silicone interaction during a-Si:H deposition on solar cell wafers bonded to glass , 2014 .

[23]  G. Nielson,et al.  Ultra-thin single crystal silicon modules capable of 450 W/kg and bending radii <1mm: Fabrication and characterization , 2013, 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC).

[24]  Niels Posthuma,et al.  Development and Integration of a High Efficiency Baseline Leading to 23% IBC Cells , 2012 .

[25]  Jan Benick,et al.  High-Efficiency c-Si Solar Cells Passivated With ALD and PECVD Aluminum Oxide , 2010, IEEE Electron Device Letters.

[26]  C. Ballif,et al.  Damage at hydrogenated amorphous/crystalline silicon interfaces by indium tin oxide overlayer sputtering , 2012 .

[27]  Development of Interdigitated Back Contact Silicon Heterojunction (IBC Si-HJ) Solar Cells , 2011 .

[28]  J. Werner,et al.  18.9% efficient full area laser doped silicon solar cell , 2009 .

[29]  R. Brendel,et al.  High-Efficiency Cells From Layer Transfer: A First Step Toward Thin-Film/Wafer Hybrid Silicon Technologies , 2011, IEEE Journal of Photovoltaics.

[30]  Niels Posthuma,et al.  Simple power-loss analysis method for high-efficiency Interdigitated Back Contact (IBC) silicon solar cells , 2012 .

[31]  R. Sinton,et al.  Contactless determination of current–voltage characteristics and minority‐carrier lifetimes in semiconductors from quasi‐steady‐state photoconductance data , 1996 .

[32]  G. Janssen,et al.  Crystalline silicon interconnected strips (XIS): Introduction to a new, integrated device and module concept , 2012, 2012 38th IEEE Photovoltaic Specialists Conference.

[33]  W. Kern.  The Evolution of Silicon Wafer Cleaning Technology , 1990 .

[34]  M. Zeman,et al.  Influence of ITO deposition and post annealing on HIT solar cell structures , 2011 .