Title:	Fully Screen-Printed Silicon Solar Cells with Local Al-BSF Base Contacts and a Voc of 711 mV
Author(s):	F. Haase, B. Min, C. Hollemann, J. Krügener, R. Brendel, R. Peibst
Topic:	Silicon Materials and Cells
Subtopic:	High Temperature Route for Si Cells
Event:	37th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2AO.6.2
ISBN:	3-936338-73-6
Price:	0,00 EUR
Document(s):	presentation

Abstract/Summary:

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We investigate the open circuit voltage potential of local aluminum-back surface fields (Al-BSF) on cell level. We implement these contacts in a cell process, which uses almost the same process equipment as PERC cells [1,2]. The most limiting factor in PERC cells is the emitter and emitter contact recombination that typically limits the open circuit voltage to values below 700 mV. We eliminate this losses channel by substituting the P-diffused emitter by a passivating n-type poly-Silicon on Oxide (POLO) contact. We place this contact on the rear side because of its strong free carrier absorption. The Al-BSF contacts are also located at the rear side to avoid front-side shading. Figure 1 shows the resulting POLO-IBC cell structure with interdigitated back contacts that uses Al-BSF for the hole selective contact and n-type POLO for the electron selective contact.