Mechanisms of adsorption of an azo-polyelectrolyte onto layer-by-layer films

Ferreira, Quirina; Gomes, Paulo J.; Maneira, M.J.P.; Ribeiro, Paulo A.; Raposo, Maria

doi:10.1016/j.snb.2007.01.007

Cited by 25 publications

(15 citation statements)

References 25 publications

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“…[25] and [40], where the adsorbed amount of POMA varied with the drying process. Although the adsorbed amount has seen to increase with roughness as revealed in POMA films [41], Ferreira et al [42,43] observed smaller roughness values in PAH/PAZO LbL films dried with a nitrogen flux than the ones observed in wet films, being the adsorbed amount behavior with the initial surface roughness for both dry and wet films similar to that obtained for POMA films. Moreover, a higher number of "globular like structures" was observed in wet PAH/PAZO films than in dried films.…”

Section: Polyelectrolyte Adsorbed Amountmentioning

confidence: 71%

Counterions in layer-by-layer films—Influence of the drying process

Lourenço

Ribeiro

Rego³

et al. 2007

Journal of Colloid and Interface Science

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Section: Polyelectrolyte Adsorbed Amountmentioning

confidence: 71%

Counterions in layer-by-layer films—Influence of the drying process

Lourenço

Ribeiro

Rego³

et al. 2007

Journal of Colloid and Interface Science

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“…All the factors mentioned above represent an important challenge and must be considered in the development of hybrid solar cells. Thus, and within the frame of work carried out in the last years under organic conductive polymers, photoluminescent and photochromic [25][26][27], and also on semiconductors oxides films, such as TiO 2 and ZnO [28,29], the present work was undertaken in order to contribute solutions to capture and convert solar energy. For that, two types of hybrid solar cell devices were developed and studied: FTO/(PAH/GO) x /TiO 2 /Al and FTO/(PAH/GO) x /ZnO/Al, where x is the number of bilayers.…”

Section: Introductionmentioning

confidence: 99%

Engineering of TiO2 or ZnO—Graphene Oxide Nanoheterojunctions for Hybrid Solar Cells Devices

et al. 2021

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It is currently of huge importance to find alternatives to fossil fuels to produce clean energy and to ensure the energy demands of modern society. In the present work, two types of hybrid solar cell devices were developed and characterized. The photoactive layers of the hybrid heterojunctions comprise poly (allylamine chloride) (PAH) and graphene oxide (GO) and TiO2 or ZnO films, which were deposited using the layer-by-layer technique and DC-reactive magnetron sputtering, respectively, onto fluorine-doped tin oxide (FTO)-coated glass substrates. Scanning electron microscopy evidenced a homogeneous inorganic layer, the surface morphology of which was dependent on the number of organic bilayers. The electrical characterization pointed out that FTO/(PAH/GO)50/TiO2/Al, FTO/(PAH/GO)30/ZnO/Al, and FTO/(PAH/GO)50/ZnO/Al architectures were the only ones to exhibit a diode behavior, and the last one experienced a decrease in current in a low-humidity environment. The (PAH/GO)20 impedance spectroscopy study further revealed the typical impedance of a parallel RC circuit for a dry environment, whereas in a humid environment, it approached the impedance of a series of three parallel RC circuits, indicating that water and oxygen contribute to other conduction processes. Finally, the achieved devices should be encapsulated to work successfully as solar cells.

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“…The interlayers formed, under similar conditions, with regular polymers (namely low molecular weight poly (9,9-dioctylfluorene), lmwPFO, and high molecular weight PFO, hmwPFO, and poly[ (9,9-dioctylfluorene)-alt-bithiophene)], F8T2, had thickness values below 1 nm, as estimated from optical absorption studies, and the performance of the corresponding LEDs could not be directly correlated with the energy of the frontier levels of the polymers used in the interlayers. Thin film growth results from atomistic processes such as surface nucleation and diffusion, 8 grain boundary motion, and deposition flux shadowing. 9 During the formation of interfaces, a competition between nucleation and diffusion processes may occur, with the polymeric chains adopting conformations that minimize their free energy on the surface.…”

Section: Introductionmentioning

confidence: 99%

Polymer Light-Emitting Diode Interlayers’ Formation Studied by Current-Sensing Atomic Force Microscopy and Scaling Laws

et al. 2009

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This work describes the use of current-sensing atomic force microscopy and dynamic scaling laws to characterize the surface morphologies of polymer light-emitting diode interlayers formed by poly(9,9-dioctylfluorene), PFO, on top of poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonic acid), PEDOT:PSS. Two types of PFO differing in molecular weight are compared. Surface current maps and calculated energy gaps of PEDOT:PSS evidence surface segregation of the two components of the blend, being PEDOT preferentially located in the surface valleys. Upon formation of PFO interlayers, an overall current decrease occurs, with this decrease being more pronounced for the interlayer based on PFO with higher molecular weight. It is observed that, under the preparation conditions used, neither of the two PFO samples leads to full coverage of the surface. The submonolayer nature of these interlayers has allowed us to establish that PFO chains are preferentially deposited in the valleys of the PEDOT:PSS surface; that is, they are anchored at doped PEDOT domains. The mechanism involved in the PFO deposition was studied using power spectral density analysis with scaling laws. This study provided quantitative information on the surface growth for each interlayer.

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Mechanisms of adsorption of an azo-polyelectrolyte onto layer-by-layer films

Cited by 25 publications

References 25 publications

Counterions in layer-by-layer films—Influence of the drying process

Counterions in layer-by-layer films—Influence of the drying process

Engineering of TiO2 or ZnO—Graphene Oxide Nanoheterojunctions for Hybrid Solar Cells Devices

Polymer Light-Emitting Diode Interlayers’ Formation Studied by Current-Sensing Atomic Force Microscopy and Scaling Laws

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