Basic Study on the Influence of Glass Composition and Aluminum Content on the Ag/Al Paste Contact Formation to Boron Emitters

Lee

Progress in Photovoltaics

et al. 2019

This study proposes a hybrid solar cell structure for a highly efficient silicon solar cell obtained by combining two passivating contact structures, namely, a heterojunction and polysilicon passivating contact. Given that the major cause of the loss in efficiency of crystalline silicon solar cells is carrier recombination at the metal‐semiconductor junction, a passivating contact having high‐quality passivation and a low contact resistance was introduced. In this study, two major passivating contact solar cells were combined. By applying an intrinsic thin amorphous silicon layer at the front and a tunneling oxide at the rear, a hybrid silicon solar cell with an efficiency of 21.8% was fabricated. Moreover, to evaluate the potential efficiency limit and to suggest methods for improving the cell performance of the proposed amorphous silicon emitter tunnel oxide back contact structure, the cell efficiency was simulated, and the result indicated that an efficiency of 26% could be achieved by controlling the thickness and resistivity of the wafer.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts

Lee

Progress in Photovoltaics

et al. 2019

“…1) [12][13][14][15]. Furthermore, it was shown that increasing the Al content limits the densification of the screenprinted metal and leads to modified glass distribution in the interface structure [16,17].…”

Section: Fundamental Understanding Of Screen Printed Contactsmentioning

confidence: 99%

Summary of the 5th Workshop on Metallization for Crystalline Silicon Solar Cells

Beaucarne¹,

Schubert

Hoornstra

2015

Energy Procedia

The 5 th Metallization Workshop took place in Constance, Germany on 20 and 21 October 2014 and provided an overview of research and development in the field of solar cell metallization. Enhanced understanding of contact structure and formation was obtained thanks to new characterization techniques. Great progress in metallization technologies was also reported. Screen printing technology is continuing its trajectory of continuous improvement, notably with fine-line screen printing (linewidth < 50 μm) becoming a reality. Ni/Cu plating technology is also progressing fast, with many of the technical barriers to adoption being successfully removed. Finally, the workshop also highlighted the move towards a module-centric design of solar cell metallization, targeting high performance and low cost at module level.

“…However, contact problems arise for boron emitters that are applied to n-type silicon solar cells using the screen-printing technique. After firing with Ag paste, the contact resistance is higher than a phosphorus emitter; this problem can be resolved by adding aluminum to the Ag paste 3 4 5 6 . However, this produces other problems, such as shunting behavior and a high line resistance 3 .…”

mentioning

confidence: 99%

Effects of Current-injection Firing with Ag Paste in a Boron Emitter

Kim

Choi

et al. 2016

Sci Rep

A high contact resistance for screen-printed contacts was observed when a conventional Ag paste was used on a boron emitter. The results of this study suggest that electron injection during firing is one of the processes that contribute to a lower contact resistance. Larger quantities of Ag precipitates formed upon electron injection into the boron emitter, which was confirmed by observing Ag crystallite or dendrite structures on the boron and by measuring the contact resistance between the boron emitter and the Ag bulk. The electron-injected sample had approximately 10000 times lower contact resistance than an untreated sample. The contact resistance of the electron-injected sample was 0.021 mΩ∙cm2 under optimal conditions, which is lower than that of conventional p-type silicon solar cells. Thus, electron injection can effectively lower contact resistance when using Ag paste in n-type silicon solar cells. During the cooling in the firing process, dissolved Ag ions in the glass layer are formed as dendrites or crystallites/particles. The dendrites are formed earlier than others via electrochemical migration under electron injection conditions. Then, crystallites and particles are formed via a silicon etching reaction. Thus, Ag ions that are not formed as dendrites will form as crystallites or particles.