Capitalizing on the Glass-Etching Effect of Silver Plating Chemistry to Contact Si Solar Cells With Homogeneous 100–110 $\Omega/\hbox{sq}$ Emitters

Cho

Progress in Photovoltaics

et al. 2016

Self Cite

Fire-through Ag thick-film metallization of crystalline Si (c-Si) solar cells often yields macroscopically non-uniform contact quality over the cell area, degrading the cell performance and causing cell-to-cell variations of the conversion efficiency in a cell production line. This study analyzes the root cause of the "gray finger" phenomenon, in which part of the firethrough Ag contact gridlines of a c-Si solar cell appears in gray or dark contrast in the electroluminescence images owing to high contact resistance. Few Ag crystallites were formed on the corrugated emitter surface at the contact interfaces underneath the gray fingers. The present results revealed that the gray finger phenomenon was caused by a short-circuit spot that formed between the Ag gridlines and underlying Si emitter during contact firing. The electrochemical reactions involved in fire-through Ag contact formation established a potential difference between the sintered Ag gridlines and Si emitter separated by molten glass. The molten glass acted as an electrolyte containing mobile Ag + and O 2À ions during contact firing. Therefore, the short-circuiting between the sintered Ag gridlines and Si emitter produced a galvanic cell during contact firing, which inhibited Ag crystallite formation at the contact interface along the gridlines in a short circuit and produced the gray fingers. The firing reactions in Ag thick-film contact formation could be interpreted in terms of the mixed potential theory of corrosion. The degradation of cell performance because of the gray finger phenomenon was also evaluated for 6-in. screen-printed c-Si solar cells.

Section: Gray Finger Phenomenon In Inkjet‐printed Cellsmentioning

confidence: 99%

Electrochemical nature of contact firing reactions for screen‐printed silicon solar cells: origin of “gray finger” phenomenon

Cho

Progress in Photovoltaics

et al. 2016

Self Cite

“…This mixture was combined with a nanoparticle Ag‐ink (DGP‐45HTG from ANP Co.) containing 32.21 wt% of 40‐nm‐sized Ag particles. Also, inks containing PbO as glass etching material are reported . To prevent sedimentation and agglomeration of the particles, binders and dispersants may be added.…”

Section: Inkjet Structuring Concepts and Suitable Inksmentioning

confidence: 99%

“…The seed and plate approach was demonstrated by Ebong et al, Kalio et al, and Buerklin, all using industrial inkjet printers. Ebong and Kalio used an inkjet printer from Xjet Solar Ltd., and Buerklin used the nanoJet from Schmid Technology GmbH.…”

Section: Metallizationmentioning

confidence: 99%

See 1 more Smart Citation

Inkjet Technology for Crystalline Silicon Photovoltaics

et al. 2014

The world's ever increasing demand for energy necessitates technologies that generate electricity from inexhaustible and easily accessible energy sources. Silicon photovoltaics is a technology that can harvest the energy of sunlight. Its great characteristics have fueled research and development activities in this exciting field for many years now. One of the most important activities in the solar cell community is the investigation of alternative fabrication and structuring technologies, ideally serving both of the two main goals: device optimization and reduction of fabrication costs. Inkjet technology is practically evaluated along the whole process chain. Research activities cover many processes, such as surface texturing, emitter formation, or metallization. Furthermore, the inkjet technology itself is manifold as well. It can be used to apply inks that serve as a functional structure, present in the final device, as mask for subsequent structuring steps, or even serve as a reactant source to activate chemical etch reactions. This article reviews investigations of inkjet-printing in the field of silicon photovoltaics. The focus is on the different inkjet processes for individual fabrication steps of a solar cell. A technological overview and suggestions about where future work will be focused on are also provided. The great variety of the investigated processes highlights the ability of the inkjet technology to find its way into many other areas of functional printing and printed electronics.

“…The obtained geometry of the seed pattern is approximately 58.5 ± 1.2 μm width with 1.81 μm height. Similarly, Ebong et al [10] employed the Xjet Solar inkjet printer to fabricate a thin seed layer. Further electroplating process was performed which could help obtain highquality contacts for high-sheet-resistance emitter.…”

mentioning

confidence: 99%

Geometrical Morphology of Inkjet-Printed Finger Electrodes on Untreated Multi-Crystalline Silicon Solar Cells

Zhang

Cheng

et al. 2019

IEEE J. Photovoltaics

The geometrical morphologies fabricated by continuous and interlacing printing modes on untreated multi-crystalline solar cells are quantitively explored for uniform and high aspectratio finger electrodes. The voltage waveform of printhead is well modulated by in-house developed inkjet prototype printer for optimizing the droplet volume and velocity. As the fingers are fabricated with continuous printing mode by varying printing parameters, the bulging and coffee ring morphologies could not be eliminated resulting from the rough and anisotropic features. The interlacing printing mode is first introduced for finger electrodes fabrication. Results show that the width of the printed finger is not influenced by the printing layers and maintains the stable values of ∼60 µm with pre-heating temperature 80°C. Moreover, the interlacing printing mode has a high tolerance of droplet spacing variance (30-45 µm) and suppresses the coffee ring morphology which obtains uniform finger electrodes. The study not only offers good guidance of finger electrodes fabrication for multi-crystalline solar cell manufacturing, but also proposes in-depth insights for the three-dimensional circuit structures fabrication of the emerging printed electronics. Index Terms-Droplet spacing, finger electrode, inkjet-printed, interlacing printing mode, multiple layers. I. INTRODUCTION T HE finger electrodes fabrication in crystalline silicon solar cell industry has been a key process which directly affects the solar cell efficiency and also constitutes a major part of product cost [1], [2]. To date, screen printing is the mainstream