Title

Optical Properties Of Screen-Printed Aluminum Contacts

Keywords

aluminum; cell optics; internal back reflectance; screen-printing; silicon; spectroscopic ellipsometry

Abstract

When attempting to analytically model the internal back reflectance (IBR) of crystalline silicon (c-Si) solar cells, knowledge of the optical properties of each material at the rear side of the cell is required. For aluminum back surface field (Al-BSF) and passivated emitter and rear cell (PERC) architectures, a screen-printed Al paste is typically used to form the rear contacts. In the literature, the complex refractive index of pure Al is typically used for this layer, even though it is well known that the composition and microstructure of these fired Al pastes is quite different than pure Al. In this work, the wavelength-dependent complex refractive index of four different fired screen-printed Al pastes are measured, resulting in a large discrepancy when compared to that of published values for pure Al. Using a two step modeling and simulation process, this discrepancy in the complex refractive index is shown to lead to differences in the calculated IBR of PERC cells. Because one of the key advantages of PERC cells is increased current due to a higher IBR with the use of thin dielectric films at the rear side of the cell, accurately defined optical properties of the Al metallization would appear to be an area of need in the photovoltaic R&D community that this work can address.

Publication Date

10-15-2014

Publication Title

2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014

Number of Pages

594-597

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1109/PVSC.2014.6924991

Socpus ID

84912124091 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84912124091

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