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Efficiency Improvement of Near‐Stoichiometric CuInSe 2 Solar Cells for Application in Tandem Devices
Author(s) -
Feurer Thomas,
Carron Romain,
Torres Sevilla Galo,
Fu Fan,
Pisoni Stefano,
Romanyuk Yaroslav E.,
Buecheler Stephan,
Tiwari Ayodhya N.
Publication year - 2019
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.201901428
Subject(s) - materials science , tandem , stoichiometry , copper indium gallium selenide solar cells , perovskite (structure) , photovoltaic system , doping , energy conversion efficiency , band gap , optoelectronics , solar cell , transparent conducting film , oxide , nanotechnology , chemical engineering , thin film , metallurgy , composite material , electrical engineering , chemistry , engineering , organic chemistry
State‐of‐the‐art Cu(In,Ga)Se 2 (CIGS) solar cells are grown with considerably substoichiometric Cu concentrations. The resulting defects, as well as potential improvements through increasing the Cu concentration, have been known in the field for many years. However, so far, cells with high Cu concentrations show decreased photovoltaic parameters. In this work, it is shown that RbF postdeposition treatment of CuInSe 2 solar cells allows for capturing the benefits from the improved absorber quality with increasing Cu content. A reduced defect density and an increased doping level for cells with high Cu concentrations close to stoichiometry are demonstrated. Implementing a high mobility front transparent conductive oxide (TCO), the improved absorbers with 1.00 eV bandgap yield a solar cell efficiency of 19.2%, and combined with a perovskite top cell a 4‐terminal tandem efficiency of 25.0% are demonstrated, surpassing the record efficiency of both subcell technologies.