Imprinted large-scale high density polymer nanopillars for organic solar cells

Aryal, Mukti; Büyükserin, Fatih; Mielczarek, Kamil; Zhao, Xiaomei; Gao, Jinming; Zakhidov, Anvar A.; Hu, Wenchuang Walter

doi:10.1116/1.2981076

Cited by 102 publications

(127 citation statements)

References 24 publications

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“…Although layers of PCBM have been spin-cast from DCM onto P3HT films in the past, 34,35 there has been essentially no work investigating either the quality of the PCBM films produced by spin-coating or the effects of spinning the PCBM top layer onto the P3HT underlayer. Thus, we begin this section with a detailed examination of the morphology of our spin-cast P3HT/PCBM bilayers.…”

Section: Resultsmentioning

confidence: 99%

“…The overall efficiency of these devices is thus likely limited only by photon harvesting, because the thin 50 nm polymer layer has an optical density at the P3HT Table 1. absorption maximum of only ∼0. 35. When the thickness of the P3HT layer is increased to 80 nm, the J sc increases because the larger absorption by the thicker polymer layer leads to the creation of additional carriers.…”

Section: Effects Of Layer Thickness On the Performance Of Bilayer Solmentioning

confidence: 99%

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Reappraising the Need for Bulk Heterojunctions in Polymer−Fullerene Photovoltaics: The Role of Carrier Transport in All-Solution-Processed P3HT/PCBM Bilayer Solar Cells

et al. 2009

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The most efficient organic solar cells produced to date are bulk heterojunction (BHJ) photovoltaic devices based on blends of semiconducting polymers such as poly(3-hexylthiophene-2,5-diyl) (P3HT) with fullerene derivatives such as [6,6]-penyl-C 61 -butyric-acid-methyl-ester (PCBM). The need for blending the two components is based on the idea that the exciton diffusion length in polymers like P3HT is only ∼10 nm, so that the polymer and fullerene components must be mixed on this length scale to efficiently split the excitons into charge carriers. In this paper, we show that the BHJ geometry is not necessary for high efficiency, and that all-solution-processed P3HT/PCBM bilayer solar cells can be nearly as efficient as BHJ solar cells fabricated from the same materials. We demonstrate that o-dichlorobenzene (ODCB) and dichloromethane serve nicely as a pair of orthogonal solvents from which sequential layers of P3HT and PCBM, respectively, can be spin-cast. Atomic force microscopy, various optical spectroscopies, and electron microscopy all demonstrate that the act of spin-coating the PCBM overlayer does not affect the morphology of the P3HT underlayer, so that our spin-cast P3HT/PCBM bilayers have a well-defined planar interface. Our fluorescence quenching experiments find that there is still significant exciton splitting in P3HT/PCBM bilayers even when the P3HT layer is quite thick. When we fabricated photovoltaic devices from these bilayers, we obtained photovoltaic power conversion efficiencies in excess of 3.5%. Part of the reason for this high efficiency is that we were able to separately optimize the roles of each component of the bilayer; for example, we found that thermal annealing has relatively little effect on the nature of P3HT layers spin-cast from ODCB, but that it significantly increases the crystallinity and thus the mobility of electrons through PCBM. Because the carriers in bilayer devices are generated at the planar P3HT/PCBM interface, we also were able to systematically vary the distance the carriers have to travel to be extracted at the electrodes by changing the layer thicknesses without altering the bulk mobility of either component or the nature of the interfaces. We found that devices have the best fill-factors when the transit times of electrons and holes through the two layers are roughly balanced. In particular, we found that the most efficient devices are made with P3HT layers that are about four times thicker than the PCBM layers, demonstrating that it is the conduction and the extraction of electrons through the fullerene that ultimately limit the performance of both bilayer and BHJ devices based on the P3HT/ PCBM material combination. Overall, we believe that polymer-fullerene bilayers provide several advantages over BHJ devices, including reduced carrier recombination and a much better degree of control over the properties of the individual components and interfaces during device fabrication.

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Section: Resultsmentioning

confidence: 99%

Section: Effects Of Layer Thickness On the Performance Of Bilayer Solmentioning

confidence: 99%

Reappraising the Need for Bulk Heterojunctions in Polymer−Fullerene Photovoltaics: The Role of Carrier Transport in All-Solution-Processed P3HT/PCBM Bilayer Solar Cells

et al. 2009

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“…Several groups have used nanoimprint lithography to produce the polymer nanostructures by using a Si mold, leading to an increase of fabrication cost [84,85]. An anodic aluminum oxide (AAO) membrane is another widely used templates for the fabrication of polymer-based nanostructures, including nanotubes, nanorods, mesoporous nanostructures and vesicles [86][87][88][89].…”

Section: Opv Structure Designmentioning

confidence: 99%

Towards High Performance Organic Photovoltaic Cells: A Review of Recent Development in Organic Photovoltaics

2014

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Organic photovoltaic cells (OPVs) have been a hot topic for research during the last decade due to their promising application in relieving energy pressure and environmental problems caused by the increasing combustion of fossil fuels. Much effort has been made toward understanding the photovoltaic mechanism, including evolving chemical structural motifs and designing device structures, leading to a remarkable enhancement of the power conversion efficiency of OPVs from 3% to over 15%. In this brief review, the advanced progress and the state-of-the-art performance of OPVs in very recent years are summarized. Based on several of the latest developed approaches to accurately detect the separation of electron-hole pairs in the femtosecond regime, the theoretical interpretation to exploit the comprehensive mechanistic picture of energy harvesting and charge carrier generation are discussed, especially for OPVs with bulk and multiple heterojunctions. Subsequently, the novel structural designs of the device architecture of OPVs embracing external geometry modification and intrinsic structure decoration are presented. Additionally, some approaches to further increase the efficiency of OPVs are described, including thermotics and dynamics modification methods. Finally, this review highlights the challenges and prospects with the aim of providing a better understanding towards highly efficient OPVs.

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“…A representative procedure is that nanostructured Si mold (template) was first fabricated through conversional etching process, and then transferred into nanopatterned films [345,346]. Recently, Aryal et al [347] introduced a novel route to fabricate nanoporous Si mold using freestanding nanoporous anodic alumina membrane as a mask for etching. More recently, AAO membranes were directly used as templates through a thermal imprinting step to synthesis freestanding poly(3-hexylthiophene) (P3HT) nanopillars [348] and cross-linked divinyltriphenylamine (DVTPA) nanorods [349].…”

Section: Lithography and Stampingmentioning

confidence: 99%

Template-based syntheses for shape controlled nanostructures

Pérez-Page

et al. 2016

Advances in Colloid and Interface Science

138

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A variety of nanostructured materials are produced through template-based synthesis methods, including zerodimensional, one-dimensional, and two-dimensional structures. These span different forms such as nanoparticles, nanowires, nanotubes, nanoflakes, and nanosheets. Many physical characteristics of these materials such as the shape and size can be finely controlled through template selection and as a result, their properties as well. Reviewed here are several examples of these nanomaterials, with emphasis specifically on the templates and synthesis routes used to produce the final nanostructures. In the first section, the templates have been discussed while in the second section, their corresponding synthesis methods have been briefly reviewed, and lastly in the third section, applications of the materials themselves are highlighted. Some examples of the templates frequently encountered are organic structure directing agents, surfactants, polymers, carbon frameworks, colloidal sol-gels, inorganic frameworks, and nanoporous membranes. Synthesis methods that adopt these templates include emulsion-based routes and template-filling approaches, such as self-assembly, electrodeposition, electroless deposition, vapor deposition, and other methods including layer-by-layer and lithography. Templatebased synthesized nanomaterials are frequently encountered in select fields such as solar energy, thermoelectric materials, catalysis, biomedical applications, and magnetowetting of surfaces.

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Imprinted large-scale high density polymer nanopillars for organic solar cells

Cited by 102 publications

References 24 publications

Reappraising the Need for Bulk Heterojunctions in Polymer−Fullerene Photovoltaics: The Role of Carrier Transport in All-Solution-Processed P3HT/PCBM Bilayer Solar Cells

Reappraising the Need for Bulk Heterojunctions in Polymer−Fullerene Photovoltaics: The Role of Carrier Transport in All-Solution-Processed P3HT/PCBM Bilayer Solar Cells

Towards High Performance Organic Photovoltaic Cells: A Review of Recent Development in Organic Photovoltaics

Template-based syntheses for shape controlled nanostructures

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