Analysis of hole transport in thin films and nanoparticle assemblies of poly(3-hexylthiophene)

Han, Xu; Bag, Monojit; Gehan, Timothy S.; Venkataraman, D.; Maroudas, Dimitrios

doi:10.1016/j.cplett.2014.07.022

Cited by 11 publications

(18 citation statements)

References 22 publications

(24 reference statements)

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“…We tried increased surfactant concentration to minimize aggregation, but found that excess surfactants can lead to dispersive charge transport, and did not consider it a viable solution. 19,20 We reasoned that the large aggregates of nanoparticles and crack formation in thin lms are due to de-wetting of the polymer nanoparticle dispersion, consistent with the observations of Krebs and co-workers. 9 Therefore, to increase surface wettability, we exposed the PEDOT:PSS layer to UV-O 3 for few minutes.…”

Section: Resultssupporting

confidence: 85%

Fabrication conditions for efficient organic photovoltaic cells from aqueous dispersions of nanoparticles

et al. 2014

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For environmentally friendly and cost-effective manufacturing of organic photovoltaic (OPV) cells, it is highly desirable to replace haloarenes with water as the active layer fabrication solvent. Replacing an organic solvent with water requires retooling the device fabrication steps. The optimization studies were conducted using poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61 butyric acid methyl ester (PCBM) as active layer materials. These materials were dispersed in water as blend and separate nanoparticles using the miniemulsion method. Topologies of the active layers were investigated using atomic force microscopy and electron microscopy techniques. We have identified two essential steps to fabricate efficient OPVs from aqueous dispersions: (1) treatment of the hole-transport layer with UV-O 3 to make the surface hydrophilic and (2) the use of an electron-transporting buffer layer for efficient charge extraction. We have also identified relative humidity and substrate temperature as key fabrication parameters for obtaining uniform active layer films. The OPV devices were fabricated using PEDOT:PSS as the hole-transport layer and PCBM as electron-transport layer with Ca/Al as the counter electrode.Efficiencies of 2.15% with a fill factor over 66% were obtained; the efficiency and the fill-factor is the highest among all aqueous processing of P3HT-PCBM nanoparticle solar cells.

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Section: Resultssupporting

confidence: 85%

Fabrication conditions for efficient organic photovoltaic cells from aqueous dispersions of nanoparticles

et al. 2014

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“…A high surfactant concentration hindered the close packing of the NPs and increased the dispersive character of the hole transport in NP films. This behavior was further observed and explained by Han et al, 88 who analyzed their TOF measurements in the frame of a conventional set of diffusion and drift equations. The authors showed that the presence of surfactants in P3HT NP films increased the trap concentration as well as the trapping rate for charge carriers (in agreement with the observed dispersive hole transport).…”

Section: Vertical Composition Through the Active Layersupporting

confidence: 53%

Recent advances in the green processing of organic photovoltaic devices from nanoparticle dispersions

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Schlatter

et al. 2020

Mater. Chem. Front.

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“…However, the presence of the sulfate group and its sodium counterion can act as charge traps and decrease the charge mobility in films . Furthermore, even when a nonionic surfactant is used, as in the case of Pluronic F127, the presence of residual free surfactant molecules in the dispersion inhibits charge transport between the donor and acceptor in the film, as reported by Xie et al The presence of surfactant in the active layer was also reported to generate more defects, resulting in higher charge trapping, according to a numerical simulation performed by Han et al Therefore, the removal of the excess surfactant was reported by many teams through washing steps, dialysis, or centrifugal dialysis. ,, Postdeposition thermal treatment was also investigated as a surfactant removal technique by Cho et al , where annealing at 270 °C was performed on poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2- b ]thiophene] (PBTTT) nanoparticles (PBTTT showing a high T g ) stabilized by SDS in order to degrade efficiently the excess of surfactant …”

Section: Incorporation In Solar Cellsmentioning

confidence: 89%

Review of Waterborne Organic Semiconductor Colloids for Photovoltaics

et al. 2021

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Development of carbon neutral and sustainable energy sources should be considered as a top priority solution for the growing worldwide energy demand. Photovoltaics are a strong candidate, and more specifically organic photovoltaics (OPV), enabling the design of flexible, light-weight, semi-transparent and low-cost solar cells. However, the active layer of OPV is, for now, mainly deposited from chlorinated solvents, harmful for the environment and for human health. Active layers processed from health and environmentally friendly solvents have over recent years formed a key focus topic of research, with the creation of aqueous dispersions of conjugated polymer nanoparticles arising. These nanoparticles are formed from organic semi-conductors (molecules and macromolecules) initially designed for organic solvents. The topic of nanoparticle OPV has gradually garnered more attention, up to a point where in 2018 it was identified as a "trendsetting strategy" by leaders in the international OPV research community. Hence, this review has been prepared to provide a timely roadmap of the formation and application of aqueous nanoparticle dispersions of active layer components for OPV. We provide a thorough synopsis of recent developments in both nanoprecipitation and miniemulsion for preparing photovoltaic inks, facilitating readers in acquiring a deep understanding of the crucial synthesis parameters affecting particle size, colloidal concentration, ink stability, and more. This review also showcases the experimental levers for identifying and optimizing the internal donor-acceptor morphology of the nanoparticles, featuring cutting-edge X-ray spectromicroscopy measurements reported over the past decade. The different strategies to improve the incorporation of these inks into OPV devices and to increase their efficiency (to the current record of 7.5%) are reported, in addition to critical design choices of surfactant type and the advantages of single-component vs. binary nanoparticle populations. The review naturally culminates by presenting the upscaling strategies in practice for this environmentally friendly and safer production of solar cells.

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Analysis of hole transport in thin films and nanoparticle assemblies of poly(3-hexylthiophene)

Cited by 11 publications

References 22 publications

Fabrication conditions for efficient organic photovoltaic cells from aqueous dispersions of nanoparticles

Fabrication conditions for efficient organic photovoltaic cells from aqueous dispersions of nanoparticles

Recent advances in the green processing of organic photovoltaic devices from nanoparticle dispersions

Review of Waterborne Organic Semiconductor Colloids for Photovoltaics

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