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Lithium Fluoride Based Electron Contacts for High Efficiency n‐Type Crystalline Silicon Solar Cells
Author(s) -
Bullock James,
Zheng Peiting,
Jeangros Quentin,
Tosun Mahmut,
Hettick Mark,
SutterFella Carolin M.,
Wan Yimao,
Allen Thomas,
Yan Di,
Macdonald Daniel,
De Wolf Stefaan,
HesslerWyser Aïcha,
Cuevas Andres,
Javey Ali
Publication year - 2016
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201600241
Subject(s) - materials science , lithium fluoride , solar cell , contact resistance , optoelectronics , wafer , doping , lithium (medication) , crystalline silicon , fermi level , silicon , semiconductor , nanotechnology , energy conversion efficiency , engineering physics , electron , inorganic chemistry , medicine , chemistry , physics , layer (electronics) , quantum mechanics , endocrinology , engineering
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 cm 2 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 LiF x /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.