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Title: Review and Understanding of Screen-Printed Contacts and Selective-Emitter Formation: Preprint

A comparison of the loss mechanisms in screen-printed solar cells relative to buried contact cells and cells with photolithography-defined contacts is presented in this paper. Model calculations show that emitter recombination accounts for about 0.5% absolute efficiency loss in conventional screen-printed cells with low-sheet-resistance emitters. Ohmic contact to high-sheet-resistance emitters by screen-printing has been investigated to regain this efficiency loss. Our work shows that good quality ohmic contacts to high sheet-resistance emitters can be achieved if the glass frit chemistry and Ag particle size are carefully tailored. The melting characteristics of the glass frit determine the firing scheme suitable for low contact resistance and high fill factors. In addition, small to regular Ag particles were found to help achieve a higher open-circuit voltage and maintain a low contact resistance. This work has resulted in cells with high fill factors (0.782) on high sheet-resistance emitters and efficiencies of 17.4% on planar float zone Si substrates, without the need for a selective emitter.
Authors:
; ;
Publication Date:
OSTI Identifier:
15009892
Report Number(s):
NREL/CP-520-36747
TRN: US200430%%1575
DOE Contract Number:
AC36-99-GO10337
Resource Type:
Conference
Resource Relation:
Conference: Prepared for the 14th Workshop on Crystalline Silicon Solar Cells and Modules, Winter Park, CO (US), 08/08/2004--08/11/2004; Other Information: PBD: 1 Aug 2004
Research Org:
National Renewable Energy Lab., Golden, CO (US)
Sponsoring Org:
US Department of Energy (US)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; CHEMISTRY; EFFICIENCY; FILL FACTORS; GLASS; MELTING; PARTICLE SIZE; RECOMBINATION; SCREEN PRINTING; SILICON SOLAR CELLS; SOLAR CELLS; SUBSTRATES; CRYSTAL GROWTH; PASSIVATION; MICROELECTRONICS; SOLAR ENERGY; PV; PHOTOVOLTAICS; CRYSTALLINE SILICON; MATERIALS AND PROCESSES; MODULE; IMPURITIES; DEVICE PROCESS; DEFECT; SOLAR ENERGY - PHOTOVOLTAICS