Charge Transport and Gradient Doping in Nanostructured Polypyrrole Films for Applications in Photocurrent Generation
| Autor: | Davi H. S. de Camargo, Leandro Merces, Carlos César Bof Bufon, Vitória B. de Morais, Guilherme L. Pozzoli, Emre Yassitepe |
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| Přispěvatelé: | Brazilian Center for Research in Energy and Materials (CNPEM), Universidade Estadual Paulista (Unesp), Federal University of Maranhaõ (UFMA) |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
Photocurrent Materials science heterojunction polymer Doping Heterojunction Nanotechnology Polymer nanomembrane Polypyrrole photocurrent nanoelectronics chemistry.chemical_compound Nanoelectronics chemistry X-ray photoelectron spectroscopy Water splitting General Materials Science gradient doping |
| Zdroj: | Scopus Repositório Institucional da UNESP Universidade Estadual Paulista (UNESP) instacron:UNESP |
| Popis: | Made available in DSpace on 2020-12-12T01:18:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 The investigation of the charge-transport mechanism across disordered conducting and semiconducting materials is of relevance, considering the applications in modern organic and hybrid electronics. The transition from bulk to nm-thick layers may lead to unexpected physical/chemical properties as the device interfaces do influence the overall charge-carrier conduction. Here, we present an investigation of the electrical transport across vertical heterojunctions having disordered nm-thick films (polypyrrole, PPy) as the active material. The PPy structures are prepared by chemical polymerization from the pyrrole vapor phase, resulting in film thicknesses of a few tens of nanometers. The electrical characteristics of the devices are evaluated as a function of voltage and temperature, and the charge transport is found to be strongly influenced by the presence of trap states at the PPy highest occupied molecular orbital-giving rise to space-charge-limited conduction with exponential distribution of traps. The trapping-state density is calculated, and X-ray photoelectron spectroscopy revealed an increase of disorder and a reduced doping density at the PPy growth interface. As a proof of concept, the PPy films integrated within the as-fabricated vertical heterostructures are applied as photosensitive devices. The observation of photocurrent is correlated to the presence of a gradient in the doping profile (from ca. 27.6 to 17.2% when thickness decreases from 120 to 20 nm). Our findings contribute to the elucidation of the charge-trapping center's origin in the nm-thick PPy films, as well as envision further applications in photoelectrochemistry, solar cells, and water splitting. Brazilian Nanotechnology National Laboratory (LNNano) Brazilian Center for Research in Energy and Materials (CNPEM) Postgraduate Program in Materials Science and Technology (POSMAT) Saõ Paulo State University (UNESP) Department of Physics (CCET) Federal University of Maranhaõ (UFMA) Postgraduate Program in Materials Science and Technology (POSMAT) Saõ Paulo State University (UNESP) |
| Databáze: | OpenAIRE |
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