Accurate Measurement of the Exciton Diffusion Length in a Conjugated Polymer Using a Heterostructure with a Side-Chain Cross-Linked Fullerene Layer

Markov, Denis E.; Amsterdam, Emiel; Blom, Paul W. M.; Sieval, and Alexander B.; Hummelen, Jan C.

doi:10.1021/jp0509663

Cited by 405 publications

(374 citation statements)

References 33 publications

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“…Such a fitting results in a value of L D typically in the range of 5-7 nm for PPV derivatives. 10,11,[13][14][15][19][20][21] Here, we measure the exciton diffusion length to estimate the efficiency of the exciton quenching in the skin layer. For simplicity, we will neglect the finite thickness of the skin layer in the modeling.…”

Section: Resultsmentioning

confidence: 99%

“…[10][11][12][13][14][15][16][17] When the polymer thickness is decreased to the order of the exciton diffusion length, the PL decay times in such a polymer-quencher heterostructure become shorter than those in the relatively thick films. The exciton diffusion length can then be estimated by modeling the thickness dependence of the PL decay process.…”

Section: Introductionmentioning

confidence: 99%

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Exciton Quenching Close to Polymer−Vacuum Interface of Spin-Coated Films of Poly(p-phenylenevinylene) Derivative

et al. 2009

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Polymer-fullerene bilayer heterostructures are suited to study excitonic processes in conjugated polymers. Excitons are efficiently quenched at the polymer-fullerene interface, whereas the polymer-vacuum interface is often considered as an exciton-reflecting interface. Here, we report about efficient exciton quenching close to the polymer-vacuum interface of spin-coated MDMO-PPV (poly[2-methoxy-5-(2′-ethyl-hexyloxy)-pphenylenevinylene]) films. The quenching efficiency is estimated to be as high as that of the polymer-fullerene interface. This efficient quenching is consistent with enhanced intermolecular interactions close to the polymer-vacuum interface due to the formation of a "skin layer" during the spin-coating procedure. In the skin layer, the polymer density is higher; that is, the intermolecular distances are shorter than in the rest of the film. The effect of exciton quenching at the polymer-vacuum interface should be taken into account when the thickness of the polymer film is on the order of the exciton diffusion length; in particular, in the determination of the exciton diffusion length.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exciton Quenching Close to Polymer−Vacuum Interface of Spin-Coated Films of Poly(p-phenylenevinylene) Derivative

et al. 2009

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“…As a result, excitons will diffuse towards the metal interface, which increases the overall efficiency of the exciton quenching process. The exciton diffusion length in conjugated polymers, typically 5 -10 nm, 12,13 is of the same order of magnitude as the estimates for the range of energy transfer to the metal. Therefore, a fundamental question to be solved is which of these two processes is mainly responsible for the quenching of excitons at metallic interfaces.…”

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confidence: 58%

“…In a recent study, we were able to extract both exciton diffusion coefficients and diffusion lengths from time-resolved PL measurements on a bilayer model system, consisting of PPV-based conjugated polymers and a polymerized fullerene. 12,14,15 In the present paper we analyze the dynamics of the quenching of excitons at metal interfaces by monitoring the timeresolved luminescence of a PPV-based conjugated polymer. Our knowledge of the exciton migration in the neat polymer enables us to disentangle the contributions from both the exciton diffusion and energy transfer to the metal, to the exciton quenching process.…”

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Migration-assisted energy transfer at conjugated polymer/metal interfaces

Markov

Blom

2005

Phys. Rev. B

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“…Spectrally resolved photoluminescence quenching (SR-PLQ) is a convenient and accurate method to measure the exciton diffusion length of organic materials used for solar cells [62]. Experimentally, the exciton diffusion length for donor polymers is ~5-15 nm [61,63,64] and ~ 40 nm for acceptor fullerene C 60 [65], while another typical acceptor PC 61 BM, has an exciton diffusion length of only 5 nm [66]. The domain size of donor and acceptor material is typically determined by the solution concentration, spin coating speed and thermal annealing temperature [67][68][69].…”

Section: Introductionmentioning

confidence: 99%

Photocurrent Limiting Mechanisms in Organic Bulk Heterojunction Solar Cells

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As we use more energy as a society, there is a greater need to become less reliant on non-renewable energy sources. Photovoltaics (PV), as a method of harvesting sunlight and converting it into electricity, provide a potential way of producing clean renewable energy.Organic bulk heteojunction (BHJ) solar cells featured with low-cost, large-area and thin-film manufacture, have become more viable with the recent demonstration with power conversion efficiencies (PCE) as high as10.7%. However, there is still a room for further improvement to reach the thermodynamic PCE limit of ~22%. For organic BHJ solar cells, the efficiency is essentially limited by the low short-circuit current density, which is determined by four sequential steps that are necessary to transform incident photons to free charge carriers. These steps are photo absorption and exciton formation, exciton diffusion, polaron pair dissociation and free polaron collection. In order to know the extent to which each of these steps limits the efficiency, a systematic study to analyze the limiting mechanisms is beneficial.In this work, we report approaches that are capable of providing insight into these processes by applying several complementary experimental techniques and theoretical calculations. The material system that are studied are poly(3-hexylthiophene) (P3HT): Therefore, it is quite intrigue to explore the reasons behind that.For absorption, the optical transfer-matrix theory is applied on the multi-thinlayer structure of organic BHJ solar cells. The complex refractive index is extracted.Meanwhile, the optical electric field and the absorption efficiency are calculated and iii AcknowledgementThe Ph.D study is a strict but a joyful scientific training. To make through it, I'd like to thank to the people who gave me tremendous support in these years.First and foremost I would like to thank my supervisor, Dr. Joe C. Campbell, for his patient guidance, continual support and encouragement during my Ph.D study. I learned a lot from him, not only about how to tackle the experimental/theoretical problems, but also about the vision, the presentation skills, and the way to keep a good relationship with your collaborators. I also appreciate the research freedom that Dr. Joe C. Campbell gave to me, which allows me to deliberate, to try and to pursuit without worrying.

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Accurate Measurement of the Exciton Diffusion Length in a Conjugated Polymer Using a Heterostructure with a Side-Chain Cross-Linked Fullerene Layer

Cited by 405 publications

References 33 publications

Exciton Quenching Close to Polymer−Vacuum Interface of Spin-Coated Films of Poly(p-phenylenevinylene) Derivative

Exciton Quenching Close to Polymer−Vacuum Interface of Spin-Coated Films of Poly(p-phenylenevinylene) Derivative

Migration-assisted energy transfer at conjugated polymer/metal interfaces

Photocurrent Limiting Mechanisms in Organic Bulk Heterojunction Solar Cells

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