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Rear interface engineering of kesterite Cu 2 ZnSnSe 4 solar cells by adding CuGaSe 2 thin layers
Author(s) -
Giraldo Sergio,
FonollRubio Robert,
Jehl LiKao Zacharie,
Sánchez Yudania,
CalvoBarrio Lorenzo,
IzquierdoRoca Victor,
PérezRodríguez Alejandro,
Saucedo Edgardo
Publication year - 2021
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3366
Subject(s) - kesterite , czts , materials science , copper indium gallium selenide solar cells , optoelectronics , photovoltaic system , band gap , nanotechnology , cadmium telluride photovoltaics , indium , photovoltaics , engineering physics , gallium , solar cell , metallurgy , electrical engineering , engineering
Kesterite Cu 2 ZnSn(S,Se) 4 thin film technology has been thoroughly investigated during the last decade as a promising solution in the field of low‐cost, sustainable, and environmental‐friendly photovoltaic technologies. However, despite efforts to boost kesterite solar cells performance by numerous strategies, the efficiencies remain stagnant around 13%. Some commonly observed issues in this technology refer to recombination events due to the likely presence of defects and, largely in line with the latest, the presence of voids and poor morphologies at the rear interface. This work, partly inspired by the copper indium gallium selenide (CIGS) technology and the use of wide‐bandgap Ga‐rich region as back surface field (BSF), focuses on an innovative approach using ultrathin CuGa layers at the rear interface to promote the formation of wide‐bandgap CuGaSe 2 , acting as an efficient electron reflector or BSF, and to function as an effective interlayer improving the kesterite crystallinity at the back interface. Kesterite Cu 2 ZnSnSe 4 devices fabricated with added CuGa layers show a general increase in photovoltaic parameters and a significantly enhanced collection efficiency compared with reference devices without CuGa. This strategy proves to be successful, for not only passivating but also for improving the Mo/kesterite interface morphology, preventing to a large extent the presence of voids at the back region of the absorber.