Firing stability of SiN_y/SiN_x stacks for the surface passivation of crystalline silicon solar cells

authored by

S. Gatz, T. Dullweber, V. Mertens, F. Einsele, R. Brendel

Abstract

In the photovoltaic industry contacts to crystalline silicon are typically formed by firing of screen-printed metallization pastes. However, the stability of surface passivation layers during high temperature contact formation is a major challenge. Here, we investigate the thermal stability of the surface passivation by amorphous silicon nitride double layers (SiN_y/SiN _x). The SiN_y passivation layer is silicon rich with refractive index larger than 3. Whereas the SiN_x capping layer has a refractive index of 2.05. Compared to pure hydrogenated amorphous silicon, the nitrogen in the SiN_y passivation layer improves the firing stability. We achieve an effective surface recombination velocity after a conventional co-firing process of (5.2±2) cm/s on p-type (1.5 Ωcm) FZ-silicon wafers at an injection density of 10¹⁵ cm^-3. An analysis of the improved firing stability is presented based on FTIR and hydrogen effusion measurements. The incorporation of an SiN_y/SiN_x stack into the passivated rear of Cz silicon screen-printed solar cells results in an energy conversion efficiency of 18.3% compared to reference solar cells with conventional aluminum back surface field showing 17.9% efficiency. The short circuit current density increases by up to 0.8 mA/cm² compared to conventional solar cells due to the improved optical reflectance and rear side surface passivation.

Organisation(s)

Institute of Solid State Physics

External Organisation(s)

Institute for Solar Energy Research (ISFH)
Forschungszentrum Jülich

Type

Article

Journal

Solar Energy Materials and Solar Cells

Volume

96

Pages

180-185

No. of pages

6

ISSN

0927-0248

Publication date

01.2012

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1016/j.solmat.2011.09.051 (Access: Closed)