Bifacial, fully screen-printed n-PERT solar cells with BF₂ and B implanted emitters

authored by

F. Kiefer, J. Krügener, F. Heinemeyer, M. Jestremski, H. J. Osten, R. Brendel, R. Peibst

Abstract

For boron implants made with ion implanters designed for PV applications, a variety of ion species BF_x (x=0.2) is implanted, while BF₂ accounts for the lions share. We investigate the impact of the BF₂ implantation dose and the annealing conditions on the resulting electrical characteristics of industrial bifacial n-type PERT solar cells. For an annealing temperature of 950 °C, we observe a steep increase in the emitter saturation current density for BF₂ implant doses above 1.75×10¹⁵ cm^-2. We compare co-annealed BF₂- and B-implanted solar cells and achieve maximum energy conversion efficiencies of 20.6% with BF₂ and 21.0% with B, respectively. Separate annealing processes for the p⁺ and n⁺ doped regions result in even higher energy conversion efficiencies of 20.8% with BF₂ and 21.5% with B emitter implant. An optimized double-layer ARC applied on the separately annealed cells further increases the efficiency up to 20.9% for BF₂ and up to 21.8% for B emitter implant. All efficiency values are independently confirmed. The solar cells have bifacial factors between 97.3% and 99.4%. The BF₂-implanted solar cells with highest efficiency feature an emitter with a sheet resistance of 180 Ω/sq. contacted by a commercially available Ag/Al paste with specific contact resistance of less than 10 mΩ cm².

Organisation(s)

Institute of Electronic Materials and Devices
Institute of Solid State Physics

External Organisation(s)

Institute for Solar Energy Research (ISFH)

Type

Article

Journal

Solar Energy Materials and Solar Cells

Volume

157

Pages

326-330

No. of pages

5

ISSN

0927-0248

Publication date

12.2016

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.2016.05.028 (Access: Closed)