Abstract
Low-resistance contact to lightly doped n-type crystalline silicon (c-Si) has long been recognized as technologically challenging due to the pervasive Fermi-level pinning effect. This has hindered the development of certain devices such as n-type c-Si solar cells made with partial rear contacts (PRC) directly to the lowly doped c-Si wafer. Here, a simple and robust process is demonstrated for achieving mΩ cm2 scale contact resistivities on lightly doped n-type c-Si via a lithium fluoride/aluminum contact. The realization of this low-resistance contact enables the fabrication of a first-of-its-kind high-efficiency n-type PRC solar cell. The electron contact of this cell is made to less than 1% of the rear surface area, reducing the impact of contact recombination and optical losses, permitting a power conversion efficiency of greater than 20% in the initial proof-of-concept stage. The implementation of the LiFx/Al contact mitigates the need for the costly high-temperature phosphorus diffusion, typically implemented in such a cell design to nullify the issue of Fermi level pinning at the electron contact. The timing of this demonstration is significant, given the ongoing transition from p-type to n-type c-Si solar cell architectures, together with the increased adoption of advanced PRC device structures within the c-Si photovoltaic industry.
Original language | English (US) |
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Article number | 1600241 |
Journal | Advanced Energy Materials |
Volume | 6 |
Issue number | 14 |
DOIs | |
State | Published - Jul 20 2016 |
Externally published | Yes |
Keywords
- contacts
- fermi levels
- lithium fluoride
- photovoltaics
- silicon solar cells
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Materials Science