Ultrafast photo-conductivity in BAMH-PPV polymer thin-films

Liang, Hongye; Cao, Wenping; Du, Min; Kim, Y.; Herman, Warren N.; Lee, C.H.

doi:10.1016/j.cplett.2005.11.071

Cited by 6 publications

(7 citation statements)

References 15 publications

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“…727 This technique has been applied to demonstrate fast, electric fieldand temperature-independent charge generation in a variety of polymer films and D:A blends. 345,346,726 Fast oscilloscopes enable more direct measurements of timeresolved photocurrent, which is typically measured as a voltage across the load resistor. In this case, the transient photocurrent results from charge carriers generated by a short-pulsed illumination of a sample (e.g., a film deposited on a glass substrate with coplanar or interdigitated electrodes) that move under an applied electric field.…”

Section: Experimental Methods For Probing Exciton and Charge Carrier ...mentioning

confidence: 99%

“…Kronemeijer et al 491 established a 2D nature of charge carrier distribution in a variety of top-gate polymer FETs and found a correlation between Urbach energies extracted from the sub-bandgap Urbach absorption tails and the DOS width obtained from modeling of FET characteristics using the Vissenberg−Matters model (see Section 8.2, Figure 24). Dispersive transport characterized by time-dependent mobility was observed using THz spectroscopy, 418,549 transient photocurrent measurements, 301,345 photo-CELIV, 550 and other methods 417 in various polymers (e.g., PPV derivatives or PFO) and their BHJs. (Some reports of time-dependent mobility obtained from photo-CELIV have been questioned in the literature due to ambiguity in data interpretation.…”

Section: Experimental Evidence Vs Modelsmentioning

confidence: 99%

“…Charge generation on subpicosecond time-scales has been reported in various molecular crystals and films, ,,, conjugated polymers, , and their HJs using various modalities of ultrafast spectroscopies and fast time-resolved photocurrents in device structures. ,− Table provides examples of observations of ultrafast charge generation in pristine materials, along with conditions under which experiments were carried out and with other pertinent observations (such as temperature and/or excitation wavelength dependence).…”

Section: Charge Carrier Photogenerationmentioning

confidence: 99%

“…Dispersive transport characterized by time-dependent mobility was observed using THz spectroscopy, , transient photocurrent measurements, , photo-CELIV, and other methods in various polymers (e.g., PPV derivatives or PFO) and their BHJs. (Some reports of time-dependent mobility obtained from photo-CELIV have been questioned in the literature due to ambiguity in data interpretation .…”

Section: Charge Transportmentioning

confidence: 99%

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Organic Optoelectronic Materials: Mechanisms and Applications

2016

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Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.

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Section: Experimental Methods For Probing Exciton and Charge Carrier ...mentioning

confidence: 99%

Section: Experimental Evidence Vs Modelsmentioning

confidence: 99%

Section: Charge Carrier Photogenerationmentioning

confidence: 99%

Section: Charge Transportmentioning

confidence: 99%

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Organic Optoelectronic Materials: Mechanisms and Applications

2016

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“…7) is electric field independent in the studied range of electric fields, similar to that reported in D/A systems with polymeric donors and PCBM acceptors. 75,76 Ultrafast charge carrier photogeneration has been observed in a variety of small-molecule and polymeric organic semiconductors via ultrafast spectroscopy methods, 26,[77][78][79] Auston switch-based techniques, 39,80,81 and fast oscilloscope detection of photocurrents. 33,54,82 In most cases, the efficiency of this process is at or below $10%, in agreement with values of n SSC (which dominates charge generation at fast time scales) extracted from our simulations.…”

Section: B D/a Compositesmentioning

confidence: 99%

Charge carrier dynamics in organic semiconductors and their donor-acceptor composites: Numerical modeling of time-resolved photocurrent

Johnson

Kendrick

Ostroverkhova

2013

Journal of Applied Physics

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We present a model that describes nanosecond (ns) time-scale photocurrent dynamics in functionalized anthradithiophene (ADT) films and ADT-based donor-acceptor (D/A) composites. By fitting numerically simulated photocurrents to experimental data, we quantify contributions of multiple pathways of charge carrier photogeneration to the photocurrent, as well as extract parameters that characterize charge transport (CT) in organic films including charge carrier mobilities, trap densities, hole trap depth, and trapping and recombination rates. In pristine ADT films, simulations revealed two competing charge photogeneration pathways: fast, occurring on picosecond (ps) or sub-ps time scales with efficiencies below 10%, and slow, which proceeds at the time scale of tens of nanoseconds, with efficiencies of about 11%–12%, at the applied electric fields of 40–80 kV/cm. The relative contribution of these pathways to the photocurrent was electric field dependent, with the contribution of the fast process increasing with applied electric field. However, the total charge photogeneration efficiency was weakly electric field dependent exhibiting values of 14%–20% of the absorbed photons. The remaining 80%–86% of the photoexcitation did not contribute to charge carrier generation at these time scales. In ADT-based D/A composites with 2 wt.% acceptor concentration, an additional pathway of charge photogeneration that proceeds via CT exciton dissociation contributed to the total charge photogeneration. In the composite with the functionalized pentacene (Pn) acceptor, which exhibits strong exciplex emission from a tightly bound D/A CT exciton, the contribution of the CT state to charge generation was small, ∼8%–12% of the total number of photogenerated charge carriers, dependent on the electric field. In contrast, in the composite with PCBM acceptor, the CT state contributed about a half of all photogenerated charge carriers. In both D/A composites, the charge carrier mobilities were reduced and trap densities and average trap depths were increased, as compared to a pristine ADT donor film. A considerably slower recombination of free holes with trapped electrons was found in the composite with the PCBM acceptor, which led to slower decays of the transient photocurrent and considerably higher charge retention, as compared to a pristine ADT donor film and the composite with the functionalized Pn acceptor.

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Photophysical and Photoconductive Properties of Novel Organic Semiconductors

Ostroverkhova

2013

Organic Electronics

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Ultrafast photo-conductivity in BAMH-PPV polymer thin-films

Cited by 6 publications

References 15 publications

Organic Optoelectronic Materials: Mechanisms and Applications

Organic Optoelectronic Materials: Mechanisms and Applications

Charge carrier dynamics in organic semiconductors and their donor-acceptor composites: Numerical modeling of time-resolved photocurrent

Photophysical and Photoconductive Properties of Novel Organic Semiconductors

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