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Doctoral theses

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Identifier 000459927
Title Development of Perovskite-Gallium Arsenide double-junction photovoltaic devices
Alternative Title Ανάπτυξη διπλής επαφής Περοβσκίτη -Γάλλιου Αρσενικού για φωτοβολταϊκές εφαρμογές
Author Μανιδάκης, Εμμανουήλ
Thesis advisor Πελεκάνος, Νικόλαος
Reviewer Στούμπος, Κωνσταντίνος
Κιοσέογλου, Γεώργιος
Κοπιδάκης, Γεώργιος
Κυμάκης, Εμμανουήλ
Στρατάκης, Εμμανουήλ
Φαλάρας, Πολύκαρπος
Abstract The perovskite solar cells represent today the most rapidly developed photovoltaic (PV) technology, as they combine low fabrication costs, high conversion efficiencies and the possibility to deposit on flexible substrates, while great progress has been accomplished recently on the stability issues of these materials under typical atmospheric conditions. On the other hand, the solar cells based on III-V semiconductors, such as GaAs, are still regarded as the reference technology in the PV industry, exhibiting the highest in the whole field PV efficiencies of 29.1% for single-junction devices and 46% for a four-junction solar cell with concentrated light. In this thesis, we attempt to combine the benefits of the above two material systems to provide a high-efficiency perovskite/GaAs tandem solar cell with enhanced characteristics. Our main findings are: o We have produced GaAs-based solar cell devices with PV efficiencies reaching ~15% values, comparing well with reported values for GaAs solar cells of similar design. Furthermore, these PV efficiencies are more than enough for the main purpose of this work, which is to demonstrate the benefits of tandem perovskite/GaAs devices. o We have developed optimized recipes, adapted to our laboratory, for the deposition of every single layer of a full perovskite PV device, including the perovskite active layer, the electron and hole transporting layers, and the metal contacts. o We have experimented with several deposition techniques such as hot-casting, antisolvent method and gas-quenching technique, to obtain high-quality perovskite films in “out-of-the-glovebox” conditions. o We have synthesized high-bandgap “red” perovskites with a gap around 650nm for the needs of the tandem perovskite/GaAs structures and examined ways to limit their phase-separation phenomena under photoexcitation. o We have fabricated “red” perovskite solar devices with the modest PV efficiency of ~6.5%, most likely attributed to the “out-of-the-glovebox” conditions. o We have realized that the rf-sputtering deposition of Indium-Tin-Oxide, as transparent electrode on top of Spiro-OMeTAD/perovskite layers, degrades severely the PV characteristics of the underneath device, suggesting that we need either to employ a milder ITO deposition method or find a protection scheme of the underneath layers during the ITO deposition. o Combining a 1.77 eV perovskite solar cell with transparent contacts, provided to us from a collaborating lab, and a GaAs solar cell developed by our group, we have managed to demonstrate a tandem 4-terminal device with a PV efficiency close to 23%. o Finally, we have demonstrated that the deposition of MAPbI3 on native nominally-undoped (100) GaAs substrates generates a giant passivation effect. X-ray photoelectron spectroscopy on ultrathin MAPbI3/GaAs and PbI2/GaAs samples suggest that some Pb-related de-oxygenation of the GaAs surface occurs and is likely at the origin of the passivation effect. Interestingly, the whole process is fully reversible, in the sense that the MAPbI3 layer can be easily removed, and the PL intensity and spectral features of the GaAs substrate are fully restored to their pristine condition.
Language English
Subject Gaas
Gaas passivation
Solar cells
Tandem solar cells
Τάντεμ Φωτοβολταϊκά
Issue date 2023-11-29
Collection   School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/1/1/1/metadata-dlib-1698751446-622040-17130.tkl Bookmark and Share
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