Publications

Skip Navigation Links.

Search for publications:


Limit search to the fields


ECN publication facebook
Title:
Improved Performance of Uncapped Al2O3 and Local Firing-Through Al-BSF in Bi-facial Solar Cells
 
Author(s):
Cesar, I.; Mewe, A.A.; Granneman, E.; Vermont, P.; Weeber, A.W.
 
Published by: Publication date:
ECN Solar Energy 3-6-2012
 
ECN report number: Document type:
ECN-M--12-015 Conference Paper
 
Number of pages: Full text:
6 Download PDF  (596kB)

Presented at: IEEE 38th Photovoltaic Specialists Conference (PVSC), Austin, Texas, USA, , 3-8 juni 2012.

Abstract:
— Silicon solar cells that dominate today’s market are H-pattern cells based on p-type silicon wafer material with a full Al Back Surface Field (BSF) as rear contact. ECN’s rear passivated bi-facial PASHA (Passivated on all sides H- pattern) and ASPIRe (All Sides Passivated and Interconnected at the Rear, MWT) concepts answer the market pressure to decrease the euro/watt price and increase the efficiency. For optimized cells we estimate 0.5-0.8% absolute higher cell efficiencies compared to the industrial standard due to better rear passivation and reflection, while thinner wafers <150um) can be processed with limited yield loss. In addition, Al paste consumption can be reduced by 50-70% owing to the open rear metallization. Here we report on the improved performance of PASHA cells passivated by an uncapped Al2O3 layer on the rear, through which Al paste is fired for contact and local aluminum BSF formation. The Al2O3 dielectric layer is deposited in the Levitrack, an industrial-type system for high-throughput Atomic Layer Deposition (ALD) developed by Levitech. On Cz and mc material, a gain in JscxVoc of 1% and 2.5% respectively is obtained compared to the reference, at a rear metal fraction of 30%. Localized IQE mapping shows that the passivation quality of the Al2O3 passivation layer is maintained after firing which is a major improvement as compared to our previous report. Furthermore, reliability tests on single cell laminates (Cz cells) suggest that the passivation layer remains stable during the lifetime of a module.


Back to List