Back surface field and emitter passivation effects in the record high efficiency n-type dendritic web silicon solar cell

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:302478

Narasimha, S; Crotty, G; Krygowski, T; Rohatgi, A ^[1]; Meier, D L ^[2]

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1. Georgia Inst. of Tech., Atlanta, GA (United States)
2. EBARA Solar, Inc., Large, PA (United States)

A solar cell efficiency of 17.3% (4 cm{sup 2} area) has been achieved on 11 {Omega}-cm, n-type dendritic web silicon. This is the highest reported efficiency to date on any silicon ribbon material. Detailed characterization and modeling show that due to the reduced substrate thickness (100 {micro}m) and long diffusion length (> 400 {micro}m), device performance is strongly dependent on the back surface recombination velocity (S{sub b}). In this study, an n{sup +} phosphorus BSF was implemented to reduce the effective S{sub b} to approximately 20 cm/s, and increase the device efficiency by nearly 4% (absolute) above the case of infinite S{sub b}. Additionally, thermal oxide passivation of the boron emitter was found to improve the cell performance by more than 0.5% (absolute). By extending model calculations to mirror solar cells (identically doped n{sup +}-p-p{sup +} and p{sup +}-n-n{sup +} devices with equivalent bulk lifetimes), it is shown that substrate type plays only a minor role in determining the overall device efficiency.

• Sponsoring Organization: Sandia National Labs., Albuquerque, NM (United States)
• OSTI ID: 302478
• Report Number(s): CONF-970953--
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
CARRIER LIFETIME
CHARGE CARRIERS
DIFFUSION LENGTH
ENERGY EFFICIENCY
MATHEMATICAL MODELS
RECOMBINATION
SILICON SOLAR CELLS
SUBSTRATES
THICKNESS