Design, Synthesen und Charakterisierung von n-Typ-Metalloxidhalbleitern als Interfacematerialien für (opto)-elektronische Bauelemente

Design, syntheses and characterization of n-type metal oxide semiconductors as interface materials for opto-electronic devices

Please always quote using this URN: urn:nbn:de:bvb:29-opus4-64537
  • Metalloxide als transparente Leiter gewinnen immer mehr an Bedeutung bei der Entwicklung innovativer, maßgeschneiderter und anwendungsorientierter Lösungen für viele zukünftige Schlüsseltechnologien, etwa im Bereich der Energieumwandlung (Photovoltaik), gedruckten organischen Nanoelektronik, neuen Beleuchtungssystemen und Oberflächenbeschichtungen (Touchscreens). Die folgende Dissertation behandelt die Durchführung und Optimierung der Syntheseverfahren von Metalloxid-basierten Nanomaterialien (MeOx) mit spezifischen Funktionalitäten. Dazu schafft eine Reihe von Charakterisierungsmethoden und Messtechniken einen vollständigen Ausblick in der Struktur, Morphologie und chemischenMetalloxide als transparente Leiter gewinnen immer mehr an Bedeutung bei der Entwicklung innovativer, maßgeschneiderter und anwendungsorientierter Lösungen für viele zukünftige Schlüsseltechnologien, etwa im Bereich der Energieumwandlung (Photovoltaik), gedruckten organischen Nanoelektronik, neuen Beleuchtungssystemen und Oberflächenbeschichtungen (Touchscreens). Die folgende Dissertation behandelt die Durchführung und Optimierung der Syntheseverfahren von Metalloxid-basierten Nanomaterialien (MeOx) mit spezifischen Funktionalitäten. Dazu schafft eine Reihe von Charakterisierungsmethoden und Messtechniken einen vollständigen Ausblick in der Struktur, Morphologie und chemischen Zusammensetzung dieser Halbleitermetalloxid-Materialien. Im Mittelpunkt stehen bewusst die anwendungsbezogenen Eigenschaften der hergestellten Metalloxide im Nanometerbereich und die Voraussetzungen, die sie als Interfacematerialien erfüllen müssen. Gedruckt auf Glas oder Folie weisen sie hohe optische Transparenz, einstellbare elektrische Leitfähigkeit, Flexibilität und Kosteneffizienz auf. Ihre Integrierung als dünne Extraktions- und Transportschichten (Interface-Elektroden) in der organischen Photovoltaik und die Analyse ihres Zersetzungsverhaltens führen zur Entwicklung und Realisierung stabiler und hocheffizienter organischer BHJ Solarzellen.show moreshow less
  • Over the past few years, there have been a large number of efforts on wetchemical synthesis of semiconductor metal oxide nanoparticles (MeOxNPs) and metal oxide precursor solutions (sMeOx) due to their decisive role in research and development of new materials and devices. The main goal of the novel synthetic routes is and remains the development of new synthesis strategies and production methods for MeOx NPs and sMeOx allowing one to precisely predict the composition, structure, size and opto‐electronic properties. In this regard in‐depth studies of synthesis and product characterizations are an important step towards more new technological applications. In the present work various sol‐gelOver the past few years, there have been a large number of efforts on wetchemical synthesis of semiconductor metal oxide nanoparticles (MeOxNPs) and metal oxide precursor solutions (sMeOx) due to their decisive role in research and development of new materials and devices. The main goal of the novel synthetic routes is and remains the development of new synthesis strategies and production methods for MeOx NPs and sMeOx allowing one to precisely predict the composition, structure, size and opto‐electronic properties. In this regard in‐depth studies of synthesis and product characterizations are an important step towards more new technological applications. In the present work various sol‐gel techniques, which should help preparation and processing of undoped and doped n‐type metal oxide semiconductor materials (ZnO NPs, Zn1‐xAlxO NPs, Zn1‐xCoxO NPs, Zn1‐xNixO NPs, Al3+ doped ZnO (sAZO), TiO2 NPs, LixTi1‐xO2 NPs) in the nanometer range, are slightly modified and performed. In order to find and to optimize a simple, cost‐effective, environmentally friendly and efficiently synthetic route the advantages and disadvantages of applied sol‐gel methods are in detail discussed and compared. Additionally, the reaction mechanisms which provide important and in‐depth insights in the formation of synthesized undoped and doped ZnO NPs, TiO2 NPs and sAZO are thoroughly analyzed. Using a wide range of characterization methods (UV‐Vis spectroscopy, XRD, SEM, TEM, FTIR spectroscopy, PL spectroscopy, Raman spectroscopy) and measurement techniques (Kelvin probe (WF), conductivity (σ)), the structural, morphological and opto‐electronic properties of produced n‐type metal oxide semiconductors (ZnO NPs, Zn1‐xAlxO NPs, Zn1‐xCoxO NPs, Zn1‐xNixO NPs, Al3+ doped ZnO (sAZO), TiO2 NPs, LixTi1‐xO2 NPs) in both bulk and thin transparent films are investigated and tested. The aim of those investigations is to gain sufficient information concerning the integration of synthesized binary metal oxides (ZnO NPs, Zn1‐xAlxO NPs, Zn1‐xCoxO NPs, Zn1‐xNixO NPs, Al3+ doped ZnO (sAZO), TiO2 NPs, LixTi1‐xO2 NPs) as interface materials or as intermediate layers in inverted organic BHJ solar cells (ioBHJ). According to achieved experimental results, the produced interfacial layers via doctor blading based on synthesized n‐type‐metal oxide semiconductor nanomaterials (ZnO NPs, Zn1‐xAlxO NPs, Zn1‐xCoxO NPs, Zn1‐xNixO NPs, Al3+ doped ZnO (sAZO), TiO2 NPs, LixTi1‐xO2 NPs) can satisfy even the most requirements for interface layers. They possess large band gaps (Eg) and the transmission (%T) of all thin transparent films in the visible range is more than ≥ 85%. The differences in the measured work functions (WF) are also not so much. The compared conductivity (σ) values confirmed that selected synthesis method and the applied coating technology can play an important role by producing thin interfacial metal oxide films with suitable physical and chemical properties. A direct comparison of synthesized (ZnO NPs, Zn1‐xAlxO NPs, Zn1‐xCoxO NPs, Zn1‐xNixO NPs, Al3+ doped ZnO (sAZO), TiO2 NPs, LixTi1‐xO2 NPs) as electron extraction layers or electron transport layers in ioBHJ solar cells provides that Al3+ doped ZnO precursor solutions (HT‐AZO or LT‐AZO) are in advantage towards particulate dispersions based on ZnO NPs. They have more compact and dense layers which include relatively good conductivity (σ) and higher transmission (%T). By the variation of their layer thickness no perceptible influence on the performance of ioBHJ solar cells are observed, compared to interfacial layers based on ZnO NPs. In addition, it is determined that TiO2 NPs and LixTi1‐xO2 NPs interface layers allow the construction of reproducible and efficiently ioBHJ solar cells and therefore they prove to be a good alternative for replacement of interface layers based on ZnO NPs. However, development and fabrication of efficient ioBHJ solar cells require intensive stability tests. The most significant studies up to now focus on fundamental degradation mechanisms of organic semiconductors, but not on the degradation behavior of metal oxide interfacial layers (MeOx NPs, sMeOx). In this regard, the effect of temperature, adsorption of oxygen (O2), diffusion of moisture or moisture vapor and UV‐light on the optical and electrical properties of metal oxide thin films (HT‐AZO or LT‐AZO) by applying damp heat test and UV radiation test were investigated and correlated to device degradation. The achieved experimental results show that the optical properties like transmittance (%T) and band gap (Eg) are not influenced by damp heat test and UV radiation test. It is recognized that the electrical properties of both HT‐ and LT‐AZO thin films, i.e. work function (WF) and conductivity (σ) showed evident degradation upon damp heat exposure indicating the strong interaction between the metal oxide surface and the ambient conditions leading to the formation of a depletion layer. Accelerated device degradation under damp heat testing underlines the formation of a barrier or depletion layer at the interface, reducing VOC, JSC, and FF.show moreshow less

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Metadaten
Author:Ivan Atanasov Litzov
URN:urn:nbn:de:bvb:29-opus4-64537
ISBN:978‐3‐944057‐34‐7
Series (Volume number):FAU Forschungen, Reihe B, Medizin, Naturwissenschaft, Technik (4)
Publisher:FAU University Press
Place of publication:Erlangen
Referee:Christoph J. Brabec
Document Type:Doctoral Thesis
Language:German
Year of Completion:2015
Embargo Date:2015/07/22
Publishing Institution:FAU University Press
Granting Institution:Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Technische Fakultät
Date of final exam:2014/12/17
Release Date:2015/07/24
Tag:Aluminium-dotierte Zinkoxidschichten (AZO); Austrittsarbeit; Feuchte-Wärme-Test; Leitfähigkeit; Metalloxidelektroden; Organische Solarzellen; Sol-Gel-Chemie; Stabilität
Aluminum-doped zinc oxide (AZO); Damp Heat Test; conductivity; device stability; inverted structure; metal oxide interfaces; sol-gel methods; work function (WF)
Pagenumber:XVI, 190 S.
Note:
Parallel erschienen als Druckausgabe bei FAU University Press
Institutes:Technische Fakultät / Department Werkstoffwissenschaften
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 62 Ingenieurwissenschaften / 620 Ingenieurwissenschaften und zugeordnete Tätigkeiten
Collections:Universität Erlangen-Nürnberg / FAU University Press
Licence (German):Creative Commons - CC BY-NC-ND - Namensnennung - Nicht kommerziell - Keine Bearbeitungen 3.0