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Coutinho Pereira CF, Borges BGAL, Sousa KRA, Holakoei S, Roman LS, Araujo CM, Cremona M, Koehler M, Marchiori CFN, Rocco MLM. Inducing molecular orientation in solution-processed thin films of fluorene-bithiophene-based copolymer: thermal annealing vs. solvent additive. RSC Adv 2024; 14:9051-9061. [PMID: 38500615 PMCID: PMC10945741 DOI: 10.1039/d3ra08066h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/22/2024] [Indexed: 03/20/2024] Open
Abstract
A deep understanding of the factors influencing the morphology of thin films based on conjugated polymers is essential to boost their performance in optoelectronic devices. Herein, we investigated the electronic structure and morphology of thin films of the copolymer poly(9,9-dioctyl-fluorenyl-co-bithiophene) (F8T2) in its pristine form as well as samples processed with the solvent additive 1,8-diiodooctane (DIO) or post-processed through thermal annealing treatment. Measurements were carried out using angle-resolved S K-edge NEXAFS (near-edge X-ray absorption fine structure) in total electron yield (TEY) and fluorescence yield (FY) detection modes. Two main transitions were observed at the S 1s NEXAFS spectra: S 1s → π* and S 1s → σ* (S-C). The observed dichroism pointed to a face-on orientation of the conjugated backbone, which was significantly increased for F8T2 films processed with DIO. Resonant Auger decay spectra were obtained and analyzed using the core-hole clock (CHC) method. An enhancement in the charge transfer process was observed for thermally annealed films, especially for samples processed with DIO, corresponding to an increase in film ordering. Furthermore, the investigated films were characterized using X-ray photoelectron spectroscopy, attesting to the presence of the thiophene unit in the samples and demonstrating that some of its sulfur atoms were positively polarized in the F8T2 films. All these experimental findings were compared with molecular dynamics (MD) simulations of film evaporation with and without DIO. The use of MD, together with mathematical modeling, was able to explain the major effects found in the experiments, including the polarization of sulfur atoms. The simultaneous use of powerful spectroscopic techniques and theoretical methods shed light on key aspects linking film morphology with fabrication procedures.
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Affiliation(s)
| | - Bruno G A L Borges
- Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ) 21941-909 Rio de Janeiro RJ Brazil
| | - Karlison R A Sousa
- Department of Physics, Federal University of Paraná (UFPR) Centro Politécnico, CP 19081 81531-900 Curitiba PR Brazil
- Fundação de Amparo à Pesquisa do Estado do Amazonas - FAPEAM 69058-030 Manaus AM Brazil
| | - Soheila Holakoei
- Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ) 21941-909 Rio de Janeiro RJ Brazil
| | - Lucimara S Roman
- Department of Physics, Federal University of Paraná (UFPR) Centro Politécnico, CP 19081 81531-900 Curitiba PR Brazil
| | - C Moyses Araujo
- Department of Engineering and Physics, Karlstad University 65188 Karlstad Sweden
- Materials Theory Division, Department of Physics and Astronomy, Uppsala University 75120 Uppsala Sweden
| | - Marco Cremona
- Departamento de Física, PUC-Rio 22453-900 Rio de Janeiro RJ Brazil
| | - Marlus Koehler
- Department of Physics, Federal University of Paraná (UFPR) Centro Politécnico, CP 19081 81531-900 Curitiba PR Brazil
| | - Cleber F N Marchiori
- Department of Engineering and Physics, Karlstad University 65188 Karlstad Sweden
| | - Maria Luiza M Rocco
- Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ) 21941-909 Rio de Janeiro RJ Brazil
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Reiker T, Liu Z, Winter C, Cappellari MV, Abradelo DG, Strassert CA, Zhang D, Zacharias H. Ultrafast electron dynamics in excited states of conjugated thiophene-fluorene organic polymer (pF8T2) thin films. Phys Chem Chem Phys 2024; 26:4736-4751. [PMID: 38251969 DOI: 10.1039/d3cp00502j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
The electronic states of poly(9,9-dioctylfluorenyl-alt-bithiophene) pF8T2 on H/Si(100) substrates, prototypical for organic photovoltaics, were investigated by ultrafast photoelectron spectroscopy and by time-resolved fluorescence studies. Occupied and unoccupied electronic states were analysed by ultraviolet photoelectron spectroscopy (UPS), static and dynamic femtosecond two-photon photoemission (2PPE), and time-correlated single photon counting (TCSPC). Time-resolved measurements allow assessment of population lifetimes of intermediate states. The combination of time-resolved photoelectron spectroscopy and fluorescence excitation allows following the electronic dynamics in excited states from the femtosecond to the nanosecond time scale. For this prototypical material the electron kinetic energy resolved lifetimes range from about a few tens of femtoseconds up to hundreds of picoseconds. After annealing these types of organic thin films the efficiency of organic solar cells usually increases. We show that annealing does not influence the initial ultrafast charge generation processes, but the long-lived states. However, the nanosecond scale fluorescence lifetimes measured by TCSPC are prolonged after annealing, which therefore is identified as the cause of a greater exciton diffusion range and thus is beneficial for charge carrier extraction.
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Affiliation(s)
- T Reiker
- Center for Soft Nanoscience, University of Münster, 48149 Münster, Germany.
- Physics Institute, University of Münster, 48149 Münster, Germany
| | - Z Liu
- Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Science, Beijing 100190, P. R. China
| | - C Winter
- Physics Institute, University of Münster, 48149 Münster, Germany
| | - M V Cappellari
- Center for Nanotechnology and Institute for Inorganic and Analytical Chemistry, University of Münster, Heisenbergstraße 11, 48149 Münster, Germany
| | - D Gonzalez Abradelo
- Center for Nanotechnology and Institute for Inorganic and Analytical Chemistry, University of Münster, Heisenbergstraße 11, 48149 Münster, Germany
| | - C A Strassert
- Center for Nanotechnology and Institute for Inorganic and Analytical Chemistry, University of Münster, Heisenbergstraße 11, 48149 Münster, Germany
| | - D Zhang
- Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Science, Beijing 100190, P. R. China
| | - H Zacharias
- Center for Soft Nanoscience, University of Münster, 48149 Münster, Germany.
- Physics Institute, University of Münster, 48149 Münster, Germany
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Bassi MDJ, Araujo Todo Bom M, Terribile Budel ML, Maltempi de Souza E, Müller dos Santos M, Roman LS. Optical Biosensor for the Detection of Infectious Diseases Using the Copolymer F8T2 with Application to COVID-19. SENSORS (BASEL, SWITZERLAND) 2022; 22:5673. [PMID: 35957230 PMCID: PMC9370833 DOI: 10.3390/s22155673] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/22/2022] [Accepted: 07/26/2022] [Indexed: 02/07/2023]
Abstract
The coronavirus pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has accelerated the development of biosensors based on new materials and techniques. Here, we present our effort to develop a fast and affordable optical biosensor using photoluminescence spectroscopy for anti-SARS-CoV-2 antibody detection. The biosensor was fabricated with a thin layer of the semiconductor polymer Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-2,2'-bithiophene-5,5'-diyl)] (F8T2) as a signal transducer material. We mounted the biosensors by depositing a layer of F8T2 and an engineered version of RBD from the SARS-CoV-2 spike protein with a tag to promote hydrophobic interaction between the protein and the polymeric surface. We validated the biosensor sensitivity with decreasing anti-RBD polyclonal IgG concentrations and challenged the biosensor specificity with human serum samples from both COVID-19 negative and positive individuals. The antibody binding to the immobilized antigen shifted the F8T2 photoluminescence spectrum even at the low concentration of 0.0125 µg/mL. A volume as small as one drop of serum (100 µL) was sufficient to distinguish a positive from a negative sample without requiring multiple washing steps and secondary antibody reactions.
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Affiliation(s)
| | - Maritza Araujo Todo Bom
- Biochemistry Department, Federal University of Paraná, Curitiba 81531-980, Brazil; (M.A.T.B.); (M.L.T.B.); (E.M.d.S.); (M.M.d.S.)
| | - Maria Luisa Terribile Budel
- Biochemistry Department, Federal University of Paraná, Curitiba 81531-980, Brazil; (M.A.T.B.); (M.L.T.B.); (E.M.d.S.); (M.M.d.S.)
| | - Emanuel Maltempi de Souza
- Biochemistry Department, Federal University of Paraná, Curitiba 81531-980, Brazil; (M.A.T.B.); (M.L.T.B.); (E.M.d.S.); (M.M.d.S.)
| | - Marcelo Müller dos Santos
- Biochemistry Department, Federal University of Paraná, Curitiba 81531-980, Brazil; (M.A.T.B.); (M.L.T.B.); (E.M.d.S.); (M.M.d.S.)
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Ben Salah Y, Altowyan AS, Mbarek M, Alimi K. Complementary Study Based on DFT of Optical and Electronic Properties of New Copolymer PVK-F8T2. Polymers (Basel) 2021; 13:polym13111805. [PMID: 34070831 PMCID: PMC8198593 DOI: 10.3390/polym13111805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 02/08/2023] Open
Abstract
This article is mainly a complementary study of a novel part of π-conjugated copolymers based on the poly (N-vinylcarbazole) (PVK) and poly (9,9-dioctylfluorene-co-bithiophene) (F8T2) unit based on the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT). This study is carried out to explore the structural and optoelectronic characteristics of a new organic material named PVK-F8T2. First, the structural, optical (absorption, photoluminescence, optical transition), electronic (molecular orbital (MO), energy-level diagram) and vibratory parameters of infrared (IR) were computed and compared with experimental studies. In addition, we calculated the level energy of the excited states and their corresponding transitions. Obviously, electronic parameters such as highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO), ionization potential (IP), electronic affinity (EA) and the energy band gap (Eg) were computed in order to elucidate the intramolecular charge transport and to establish the energetic diagrams of the PVK-F8T2 copolymer for different states. The results obtained looked with precision at future optoelectronic applications. From these results, we have shown that the PVK-F8T2 has significant optoelectronic properties and seems usable as an active layer in organic light-emitting diodes (OLEDs).
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Affiliation(s)
- Yasmine Ben Salah
- College of Sciences of Monastir, Monastir University, Monastir 5000, Tunisia; (Y.B.S.); (K.A.)
| | - Abeer S. Altowyan
- Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia
- Correspondence: (A.S.A.); (M.M.)
| | - Mohamed Mbarek
- College of Sciences of Monastir, Monastir University, Monastir 5000, Tunisia; (Y.B.S.); (K.A.)
- Correspondence: (A.S.A.); (M.M.)
| | - Kamel Alimi
- College of Sciences of Monastir, Monastir University, Monastir 5000, Tunisia; (Y.B.S.); (K.A.)
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Ultra-fast charge transfer between fullerenes and a gold surface, as prepared by electrospray deposition. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Borges BGAL, Roman LS, Rocco MLM. Femtosecond and Attosecond Electron Transfer Dynamics of Semiconductors Probed by the Core-Hole Clock Spectroscopy. Top Catal 2019. [DOI: 10.1007/s11244-019-01189-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Larrude DG, Garcia-Basabe Y, Freire Junior FL, Rocco MLM. Electronic structure and ultrafast charge transfer dynamics of phosphorous doped graphene layers on a copper substrate: a combined spectroscopic study. RSC Adv 2015. [DOI: 10.1039/c5ra12799h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spectroscopy characterization on a phosphorous doped graphene layer suggests p-type doping governed by an electron transfer mechanism with a cupper substrate.
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Affiliation(s)
- Dunieskys Gonzalez Larrude
- Graphene and Nano-materials Research Center – MackGraphe
- Mackenzie Presbyterian University
- São Paulo
- Brazil
- Physics Department
| | - Yunier Garcia-Basabe
- Institute of Chemistry
- Federal University of Rio de Janeiro
- Rio de Janeiro
- Brazil
- Federal University of Latin-American Integration
| | - Fernando Lázaro Freire Junior
- Physics Department
- Pontifícia Universidade Católica do Rio de Janeiro
- Rio de Janeiro
- Brazil
- Brazilian Center for Physical Research
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