Interfacial Segregation in Polymer/Fullerene Blend Films for Photovoltaic Devices

Germack, David S.; Chan, Catherine; Kline, R. Joseph; Fischer, Daniel A.; Gundlach, David J.; Toney, Michael F.; Richter, Lee J.; DeLongchamp, Dean M.

doi:10.1021/ma100027b

Cited by 182 publications

(262 citation statements)

References 40 publications

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“…Another explanation is based on the link between enrichment and substrate surface energy. In ref 46, it has been shown that by consistently changing the material of the substrate into one with lower surface energy, the enrichment of PCBM also systematically decreased. The affinity of P3HT/PCBM with various cathode materials is an important question worth exploring, which we plan to investigate in the future using this framework.…”

Section: Resultsmentioning

confidence: 99%

Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

Lee

Wodo

Ganapathysubramanian

et al. 2014

ACS Appl. Mater. Interfaces

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The nanomorphologies of the bulk heterojunction (BHJ) layer of polymer solar cells are extremely sensitive to the electrode materials and thermal annealing conditions. In this work, the correlations of electrode materials, thermal annealing sequences, and resultant BHJ nanomorphological details of P3HT:PCBM BHJ polymer solar cell are studied by a series of large-scale, coarse-grained (CG) molecular simulations of system comprised of PEDOT:PSS/ P3HT:PCBM/Al layers. Simulations are performed for various configurations of electrode materials as well as processing temperature. The complex CG molecular data are characterized using a novel extension of our graph-based framework to quantify morphology and establish a link between morphology and processing conditions. Our analysis indicates that vertical phase segregation of P3HT:PCBM blend strongly depends on the electrode material and thermal annealing schedule. A thin P3HT-rich film is formed on the top, regardless of bottom electrode material, when the BHJ layer is exposed to the free surface during thermal annealing. In addition, preferential segregation of P3HT chains and PCBM molecules toward PEDOT:PSS and Al electrodes, respectively, is observed. Detailed morphology analysis indicated that, surprisingly, vertical phase segregation does not affect the connectivity of donor/acceptor domains with respective electrodes. However, the formation of P3HT/PCBM depletion zones next to the P3HT/PCBM-rich zones can be a potential bottleneck for electron/hole transport due to increase in transport pathway length. Analysis in terms of fraction of intraand interchain charge transports revealed that processing schedule affects the average vertical orientation of polymer chains, which may be crucial for enhanced charge transport, nongeminate recombination, and charge collection. The present study establishes a more detailed link between processing and morphology by combining multiscale molecular simulation framework with an extensive morphology feature analysis, providing a quantitative means for process optimization.

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Section: Resultsmentioning

confidence: 99%

Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

Lee

Wodo

Ganapathysubramanian

et al. 2014

ACS Appl. Mater. Interfaces

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“…The DSIMS results have, also, been supported by variable-angle spectroscopy ellipsometry (VASE), X-ray photoelectron spectroscopy (XPS), near-edge Xray absorption fine structure spectroscopy (NEXAFS) and neutron reflectivity (NR) studies in our laboratories and elsewhere. 42,[47][48][49][50][51] It should also be noted that the distribution of components normal to the film surface is also dependent on the nature of the solvent used. 52 The interactions between the conjugated polymer, here P3HT, and PCBM, that is, their miscibility, and the solubility of the components in the solvent use for film preparation are important parameters that must be considered in describing and controlling the morphology of the resultant active layer.…”

Section: Thermal Annealing Approachmentioning

confidence: 99%

On the morphology of polymer‐based photovoltaics

Liu

Jung

et al. 2012

J Polym Sci B Polym Phys

308

248

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We review the morphologies of polymer-based solar cells and the parameters that govern the evolution of the morphologies and describe different approaches to achieve the optimum morphology for a BHJ OPV. While there are some distinct differences, there are also some commonalities. It is evident that morphology and the control of the morphology are important for device performance and, by controlling the thermodynamics, in particular, the interactions of the components, and by controlling kinetic parameters, like the rate of solvent evaporation, crystallization and phase separation, optimized morphologies for a given system can be achieved. While much research has focused on P3HT, it is evident that a clearer understanding of the morphology and the evolution of the morphology in low bad gap polymer systems will increase the efficiency further. While current OPVs are on the verge of breaking the 10% barrier, manipulating and controlling the morphology will still be key for device optimization and, equally important, for the fabrication of these devices in an industrial setting.

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“…This has been shown to be critical in understanding how some devices operate, as for example in section 4.2, where charge transport in the vicinity of the donor-acceptor heterojunction of an OPV had a more substantial effect on GR than did the meso-scale morphology. However, some features on the meso-scale are of interest, such as the presence of wetting layers [443] which accumulate at the electrodes OPVs [444][445][446][447][448], or the degree of mixing of the matrix and dye in an OLED [449]. Furthermore, although research has generally centred on what optical and electronic properties using a blend of OSCs can endow a device (e.g.…”

Section: Different Ways Of Defining Morphologymentioning

confidence: 99%

Simulating charge transport in organic semiconductors and devices: a review

Groves

2016

Rep. Prog. Phys.

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractCharge transport simulation can be a valuable tool to better understand, optimise and design organic transistors (OTFTs), organic photovoltaics (OPVs), and light-emitting diodes (OLEDs). This review presents an overview of common charge transport and device models; namely drift-diffusion, master equation, mesoscale kinetic Monte Carlo and quantum chemical Monte Carlo, and a discussion of the relative merits of each. This is followed by a review of the application of these models as applied to charge transport in organic semiconductors and devices, highlighting in particular the insights made possible by modelling. The review concludes with an outlook for charge transport modelling in organic electronics.

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Interfacial Segregation in Polymer/Fullerene Blend Films for Photovoltaic Devices

Cited by 182 publications

References 40 publications

Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

On the morphology of polymer‐based photovoltaics

Simulating charge transport in organic semiconductors and devices: a review

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