Crystal network formation in organic solar cells

Dittmer, Janke J.; Lazzaroni, Roberto; Leclère, Ph.; Moretti, P. F.; Granström, Magnus; Petritsch, K.; Marseglia, E.; Friend, Richard H.; Brédas, Jean‐Luc; Rost, H.; Holmes, Andrew B.

doi:10.1016/s0927-0248(99)00096-3

Cited by 145 publications

(83 citation statements)

References 27 publications

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“…The redshift of the C6 absorption peak caused by thermal annealing is an indication of improvement in conjugation length of the C6 molecules in the blend [27]. Thermal annealing improves conjugation length of both polymers as well as small organic molecules which are much more likely to crystallize than the polymer in dye/polymer blend photovoltaic cells, as stated by Dittmer et al [28]. However the improvement in the conjugation length of the C6 dye is small as a result of small molecular weight and short conjugation of the small molecule.…”

Section: Effect Of Thermal Annealingmentioning

confidence: 83%

Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative

Ismail

Soga

Jimbo

2011

Advances in OptoElectronics

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We have fabricated bulk heterojunction organic solar cells using coumarin 6 (C6) as a small organic dye, for light harvesting and electron donation, with fullerene derivative [6,6]-phenyl-C 61 butyric acid methyl ester (PCBM), acting as an electron acceptor, by spin-coating technique. We have investigated thermal annealing and blend concentration effects on light harvesting, photocurrent, and performance parameters of the solar cells. In this work, we introduced an experimental method by which someone can easily detect the variation in the contact between active layer and cathode due to thermal annealing after cathode deposition. We have showed, in this work, unusual behavior of solar cell composed of small organic molecules under the influence of thermal annealing at different conditions. This behavior seemed uncommon for polymer solar cells. We try from this work to understand device physics and to locate a relationship between production parameters and performance parameters of the solar cell based on small organic molecules.

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Section: Effect Of Thermal Annealingmentioning

confidence: 83%

Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative

Ismail

Soga

Jimbo

2011

Advances in OptoElectronics

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“…An interesting work was carried out on ethylpropylsubstituted PBI at the imide periphery which was blended with a variety of donor polymers using spin coating techniques to prepare photovoltaic devices. It was shown that the tendency of such PBI acceptor to form crystalline domains was limiting the efficiencies of devices by creation of electron traps thus reducing the photocurrent [31,32]. On the contrary, their high crystallinity could be exploited when this ethylpropyl-substituted PBI was blended with discotic liquid crystal alkylated hexabenzocoronene (HBC) (Fig.…”

Section: Non-fullerenes Acceptors For Organic Solar Cellsmentioning

confidence: 99%

An overview of molecular acceptors for organic solar cells

Hudhomme

2013

EPJ Photovolt.

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Organic solar cells (OSCs) have gained serious attention during the last decade and are now considered as one of the future photovoltaic technologies for low-cost power production. The first dream of attaining 10% of power coefficient efficiency has now become a reality thanks to the development of new materials and an impressive work achieved to understand, control and optimize structure and morphology of the device. But most of the effort devoted to the development of new materials concerned the optimization of the donor material, with less attention for acceptors which to date remain dominated by fullerenes and their derivatives. This short review presents the progress in the use of non-fullerene small molecules and fullerene-based acceptors with the aim of evaluating the challenge for the next generation of acceptors in organic photovoltaics.

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“…It is shown that annealing enhances the quantum efficiency probably through electron conducting perylene crystal grow 48 . Blend could be used in three organic layer devices.…”

Section: Figure 9: Bulk Heterojunctions Different Possible Contactsmentioning

confidence: 99%

Organic Photovoltaic Cells: History, Principle and Techniques

Bérnède

2008

J. Chil. Chem. Soc.

147

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In this review we present an overview of the different organic solar cells families. After recalling shortly the specificities of organic materials, the band structure, the electronic properties and the charge separation process in organic materials are shortly described. Then the new organic solar cell concepts are presented. Plastic organic solar cells consist either of two organic layers or a homogeneous mixture of two organic materials. One of them -either an organic dye or a semiconducting polymer -donates the electrons. The other component serves as the electron acceptor. Principles of these multi-layers and bulk heterojunctions are presented and discussed. Then some typical examples are presented, showing the fast evolution of the cells performances. Finally, a specific attention is devoted to the interfaces electrodes/organics. Indeed recent results show that, at least in the case of multi-layers cells, the introduction of thin buffer layers at the interfaces cathode/organic acceptor and/or anode/organic donor, can strongly improve the efficiency of the organic solar cells. About the interface organic acceptor/cathode, we report the influence of an exciton-blocking layer and/or an Al 2 O 3 thin layer on the efficiency of CuPc/C 60 based photovoltaic cells. The presence, or not, of a thin Al 2 O 3 layer depends on the encapsulating process of the devices. In the case of glass/ITO/CuPc/C 60 /Al cells, the presence of an Al 2 O 3 thin layer at the interface "organic acceptor/aluminium" increases strongly the open circuit voltage of the cells but decreases slightly their short circuit current and fill factor. In the case of glass/ITO/CuPc/C 60 /Alq 3 /Al cells, the open circuit voltage is systematically higher than without Alq 3 . However, in that case, the presence of Al 2 O 3 does not improve significantly the cell performances. All these results are discussed in terms of series and shunt resistance values related to possible oxygen contamination and organic covalent action with the Al films. The effectiveness of these different phenomena depends on the presence, or not, of Alq 3 and/or Al 2 O 3 layers.About the interface anode/organic donor, it is shown that an ultra thin metallic film improves significantly the short circuit current and the cell performances. The anode in plastic solar cells, which is a transparent conductive oxide (TCO), is usually an indium tin oxide film (ITO). Indeed, when a ZnO anode is used, cells performances are far from those achieved with ITO. However, strong improvement of the cells efficiency is encountered when an ultra thin buffer layer is introduced between the ZnO and the organic film. The presence of this ultra thin buffer layer at the surface of the TCO allows decreasing the performance difference between the cells using ITO and those using ZnO. More generally such ultra thin buffer layer improves the solar cells performances.

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Crystal network formation in organic solar cells

Cited by 145 publications

References 27 publications

Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative

Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative

An overview of molecular acceptors for organic solar cells

Organic Photovoltaic Cells: History, Principle and Techniques

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