Suchergebnisse

In this work, metal-insulator-semiconductor structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al2O3), silicon nitride, and silicon oxide (SiOx) to be used as passivation layers in Cu(In,Ga)Se-2 (CIGS) thin-film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance versus conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q(f)). The density of interface defects (D-it) was estimated from capacitance versus conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 degrees C) and the use of a sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiOx deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower Dit values was Al2O3 when deposited by sputtering. ; This work was supported by European Union's Horizon 2020 research and innovation programme ARCIGS-M project under Grant 720887. The work of J. M. V. Cunha and P. M. P. Salome was supported by the Fundacao para a Ciencia e a Tecnologia (FCT) through the project IF/00133/2015. The work of J. P. Teixeira and J. P. Leitao was supported by the FCT through the project UID/CTM/50025/2013. The work of B. Vermang was supported by the European Research Council under the European Union's Horizon 2020 research and innovation programme under Grant 715027.

In the past years, the strategies used to break the Cu(In,Ga)Se-2 (CIGS) light to power conversion efficiency world record value were based on improvements of the absorber optoelectronic and crystalline properties, mainly using complex post-deposition treatments. To reach even higher efficiency values, further advances in the solar cell architecture are needed, in particular, with respect to the CIGS interfaces. In this study, we evaluate the structural, morphological and optoelectronic impact of an Al2O3 layer as a potential front passivation layer on the CIGS properties, as well as an Al2O3 tunneling layer between CIGS and CdS. Morphological and structural analyses reveal that the use of Al2O3 alone is not detrimental to CIGS, although it does not resist to the CdS chemical bath deposition. The CIGS optoelectronic properties degrade when the CdS is deposited on top of Al2O3. Nonetheless, when Al2O3 is used alone, the optoelectronic measurements reveal a positive impact of this inclusion such as a very low concentration of interface defects while keeping the same CIGS recombination channels. Thus, we suggest that an Al2O3 front passivation layer can be successfully used with alternative buffer layers. Depth-resolved microscopic analysis of the CIGS interface with slow-muons strongly suggests for the first time that low-energy muon spin spectroscopy (LE-mu SR) is sensitive to both charge carrier separation and bulk recombination in complex semiconductors. The demonstration that Al2O3 has the potential to be used as a front passivation layer is of significant importance, considering that Al2O3 has been widely studied as rear interface passivation material. (C) 2020 Published by Elsevier Ltd. ; This work was supported in part by NovaCell (028075) and InovSolarCells (029696) and in part by FunrIa(do para a Ciencia c a Tecnologia and the ERDF through COMPETE2020. Fundacao para a Ciencia e a Tecnologia (FCT) is further acknowledged through 1F/00133/2015, PD/BD/142780/2018 and SFREHBD/1/1677G/2019. The European Union's Horizon 2020 research and innovation programme ARCIGS-M project (Grant agreement 720887) is also acknowledged. The financial support by National Funds through the FCT -Fundacao para a Ciencia e a Tecnologia, I.P., under the scope of the projects MB/50025/2020 and UIDP/50025/2020 -Programatico, are acknowledged. W. C. thanks the individual grant financed by the SusPhotoSolutions project CENTRO-01-0145-FEDER-000005. P. A. Fernandes would like to acknowledge FCT for the support of the project FCT UIDB/04730/2020. This work was supported with funds from FEDER (Programa Operacional Factores de Competitividade COMPETE) and from FCT [Fundacao para a Ciencia e Tecnologia (Portugal)] under Projects No. UID/FIS/04564/2016 and No. PTDC/FIS-MAC/29696/2017. The muon experiments were performed at the Swiss Muon Source SO, Paul Scherrer Institute, Villigen, Switzerland. The authors would like to thanks to Dr. Guy Brammertz for the helping in the interpretation of the TRPL data. ; Curado, MA (corresponding author), INL, Int Iberian Nanotechnol Lab, P-4715330 Braga, Portugal. marco.alberto@inl.int