Understanding and Use of IR Belt Furnace for Rapid Thermal Firing of Screen-Printed Contacts to Si Solar Cells

Cooper, Ian B.; Ebong, Abasifreke; Renshaw, John S.; Reedy, R. C.; Al‐Jassim, Mowafak; Rohatgi, A.

doi:10.1109/led.2010.2044363

Cited by 31 publications

(13 citation statements)

References 9 publications

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“…The hypothesis is that in this experiment the efficiency after extended co-firing was limited by a poor contact because temperature profile was optimized for gettering effect but not for contacting. Besides the dissolution and gettering of lifetime-killing impurities, the cofiring step must also ensure a low contact resistance, etching uniformly the dielectric and forming Ag crystallites to allow the flow of photogenerated carriers to the contact; in addition, it must avoid p-n-junction shunting by over-firing [14].…”

Section: Extended Co-firing On Contaminated Mc-simentioning

confidence: 99%

Impact of Extended Contact Cofiring on Multicrystalline Silicon Solar Cell Parameters

Peral

Dastgheib-Shirazi

Fano

et al. 2017

IEEE J. Photovoltaics

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Section: Extended Co-firing On Contaminated Mc-simentioning

confidence: 99%

Impact of Extended Contact Cofiring on Multicrystalline Silicon Solar Cell Parameters

Peral

Dastgheib-Shirazi

Fano

et al. 2017

IEEE J. Photovoltaics

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“…4, texture pyramid silhouettes are easily seen on both emitters and at both firing temperature extremes suggesting that the Ag/c-Si IGF resulting from contact formation are thin and IGF thickness may be independent of emitter [P surface ] and peak firing temperature. It is known that thin IGF are necessary for low Ag/c-Si contact resistance [22]. Furthermore, it has been speculated that, within thin IGF, Ag may be dissolved at high enough concentration to produce a film containing conductive nano-Ag colloids, which may contribute to carrier conduction from emitter to bulk Ag gridline [6], [15].…”

Section: Microstructural Analysis Of Ag/c-si Contact Interfacementioning

confidence: 99%

Investigation of the Mechanism Resulting in low Resistance Ag Thick-Film Contact to Si Solar Cells in the Context of Emitter Doping Density and Contact Firing for Current-Generation Ag Paste

Cooper

Tate

Renshaw

et al. 2014

IEEE J. Photovoltaics

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Screen-printed thick-film Ag metallization has become highly successful in crystalline Si (c-Si) photovoltaics. However, a complete understanding of the mechanism resulting in low resistance contact is still lacking. In order to shed light on this mechanism for current-generation Ag paste, Si solar cells were fabricated using a range of emitter doping densities and contact firing conditions. Low resistance contact was found to vary as a function of emitter surface P concentration ([P su rface ]) and peak firing temperature. Scanning electron microscope (SEM) analysis revealed thin interfacial glass films (IGF) under the bulk Ag gridline. SEM analysis also showed increasing Ag crystallite density as both emitter [P su rface ] and peak firing temperature increased. Two mechanisms are proposed in forming low resistance contact to highly doped emitters: 1) formation of ultrathin IGF and/or nano-Ag colloids at low firing temperature, and 2) formation of Ag crystallites at high firing temperature. However, on lightly doped emitters, low resistance contact was achieved only at higher firing temperatures, concomitant with increasing Ag crystallite density, and suggests that thin IGF decorated with nano-Ag colloids may not be sufficient for low resistance contact to lightly doped emitters.

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“…The method for contact co-firing employed fast temperature ramping to and short dwell time at the Ag grid sinter point to foster low Ag/Si contact resistance and promote formation of uniform Al back surface field [9]. Figure 5 shows a typical contact co-firing profile used for screenprinted and direct printed PV159.…”

Section: Methodsmentioning

confidence: 99%

Improved front side metallization for silicon solar cells by direct printing

Chen

Church

Yang

et al. 2011

2011 37th IEEE Photovoltaic Specialists Conference

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This work presents a direct printing technology and an enabling tool for forming very fine gridlines with high aspect ratios that improve the front side metallization of silicon solar cells. The parallel printing setup is anticipated to print each cell in two seconds. The conductive gridlines were formed by a one-step non-contact approach at high speeds using a modified standard screen printable paste. The line width is as small as 40µm, and the line thickness is more than 30µm after firing. The front shading area is significantly reduced, and a previous study has demonstrated up to 0.5% absolute cell efficiency increase as compared to the screen-printing process baseline when the same grid pattern was used. Due to further reduction of grid line width, the pitch between each grid line increases, which affects the travel distance of the electrons excited by photon interaction, which affects the fill factor and ultimately the efficiency of the cell. In addition to the previous comparison study of wafers using the same grid pattern, this study investigated the cell performance using a modified gridline pattern that has an increased number of gridlines. The results showed an absolute efficiency increase up to 0.7%. Other electrical attributes of direct printed high aspect ratio gridlines in terms of ISC, VOC, FF and other data are also presented.

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Understanding and Use of IR Belt Furnace for Rapid Thermal Firing of Screen-Printed Contacts to Si Solar Cells

Cited by 31 publications

References 9 publications

Impact of Extended Contact Cofiring on Multicrystalline Silicon Solar Cell Parameters

Impact of Extended Contact Cofiring on Multicrystalline Silicon Solar Cell Parameters

Investigation of the Mechanism Resulting in low Resistance Ag Thick-Film Contact to Si Solar Cells in the Context of Emitter Doping Density and Contact Firing for Current-Generation Ag Paste

Improved front side metallization for silicon solar cells by direct printing

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