Bulk Heterojunction Photovoltaic Active Layers via Bilayer Interdiffusion

Chen, Dian; Liu, Feng; Wang, Cheng; Nakahara, Atsuhiro; Russell, Thomas P.

doi:10.1021/nl200552r

Cited by 277 publications

(426 citation statements)

References 48 publications

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“…Specifically, more PCBM is accumulated in the surface layer and the mid-layer adjacent to the surface layer in the MD-P3HT/PCBM film. It has been shown that the degree of PCBM diffusion in a P3HT matrix is closely related to the crystallinity of P3HT in that PCBM more easily passes through amorphous P3HT than crystalline P3HT 13 . In the present work, the crystallinity of P3HT and SD-P3HT were found to be comparable while that of MD-P3HT was significantly poorer.…”

Section: Discussionmentioning

confidence: 99%

“…This is due to an increasing interest in taking advantage of the nanometer scale resolution provided by neutron reflectometry (NR)/scattering to probe the structure, interface and morphology of bulk heterojunctions (BHJ) in organic photovoltaics (OPV) [9][10][11][12][13][14][15] to determine not only the nanoscopic heterogeneity of donor/acceptor components, but their degree of mixing and the vertical composition. The nanoscopic morphological information provided by isotopic substitution is highly relevant to understand exciton diffusion and charge transport in these devices [9][10][11][12][13][14][15] ; however, deuteration is commonly believed to have little effect on morphology. Only recently, small-angle neutron scattering revealed that deuterium substitution can significantly influence the phase separation kinetics and morphology in some polymer blend systems 16,17 .…”

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confidence: 99%

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The isotopic effects of deuteration on optoelectronic properties of conducting polymers

et al. 2014

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The attractive optoelectronic properties of conducting polymers depend sensitively upon intra-and inter-polymer chain interactions, and therefore new methods to manipulate these interactions are continually being pursued. Here, we report a study of the isotopic effects of deuterium substitution on the structure, morphology and optoelectronic properties of regioregular poly(3-hexylthiophene)s with an approach that combines the synthesis of deuterated materials, optoelectronic properties measurements, theoretical simulation and neutron scattering. Selective substitutions of deuterium on the backbone or side-chains of poly(3-hexylthiophene)s result in distinct optoelectronic responses in poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) photovoltaics. Specifically, the weak non-covalent intermolecular interactions induced by the main-chain deuteration are shown to change the film crystallinity and morphology of the active layer, consequently reducing the short-circuit current. However, side-chain deuteration does not significantly modify the film morphology but causes a decreased electronic coupling, the formation of a charge transfer state, and increased electron-phonon coupling, leading to a remarkable reduction in the open circuit voltage.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

The isotopic effects of deuteration on optoelectronic properties of conducting polymers

et al. 2014

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“…With TEM and GIXD experiments, they confirmed that the diffusion process did not disrupt the morphology established by P3HT and the interdiffusion driven morphology is essentially the same with homogenously mixed BHJ active layer. 56 In fact, the device performances achieved with this postdiffusion route were as good as when the P3HT and PCBM were initially uniformly mixed. [56][57][58][59] Solvent Annealing Approach Solvent annealing is another effective method that has been used to induce phase separation in P3HT:PCBM blends.…”

Section: Thermal Annealing Approachmentioning

confidence: 92%

“…56 In fact, the device performances achieved with this postdiffusion route were as good as when the P3HT and PCBM were initially uniformly mixed. [56][57][58][59] Solvent Annealing Approach Solvent annealing is another effective method that has been used to induce phase separation in P3HT:PCBM blends. When the solvent vapor enters the mixture, the mobility of both the P3HTand PCBM increases, enabling the P3HT to crystallize and drive the segregation of the PCBM.…”

Section: Thermal Annealing Approachmentioning

confidence: 92%

On the morphology of polymer‐based photovoltaics

Liu

Jung

et al. 2012

J Polym Sci B Polym Phys

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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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“…However, this may not be as stable as a fully conjugated donor-acceptor block copolymer system due to the migration and movement of PCBM through the polymer film. For example, recent work has shown that the complete diffusion of PCBM through amorphous P3HT (100-nm thick film) takes place within $5 s at 150 C. 217 The work of Gu et al 218 provides an example of a block copolymer and PCBM system. Here, they synthesized a P3HT-block-PS copolymer and added PCBM to make devices that had a maximum optimized device efficiency of 1.93% after thermally annealing the layer.…”

Section: Processingmentioning

confidence: 99%

Block copolymer strategies for solar cell technology

Topham¹,

Parnell²,

Hiorns³

2011

J Polym Sci B Polym Phys

186

169

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A simple overview of the methods used and the expected benefits of block copolymers in organic photovoltaic devices is given in this review. The description of the photovoltaic process makes it clear how the detailed self-assembly properties of block copolymers can be exploited. Organic photovoltaic technology, an inexpensive, clean and renewable energy source, is an extremely promising option for replacing fossil fuels. It is expected to deliver printable devices processed on flexible substrates using high-volume techniques. Such devices, however, currently lack the long-term stability and efficiency to allow organic photovoltaics to surpass current technologies. Block copolymers are envisaged to help overcome these obstacles because of their long term structural stability and their solid-state morphology being of the appropriate dimensions to efficiently perform charge collection and transfer to electrodes.

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Bulk Heterojunction Photovoltaic Active Layers via Bilayer Interdiffusion

Cited by 277 publications

References 48 publications

The isotopic effects of deuteration on optoelectronic properties of conducting polymers

The isotopic effects of deuteration on optoelectronic properties of conducting polymers

On the morphology of polymer‐based photovoltaics

Block copolymer strategies for solar cell technology

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