Detailed Investigation of Light Induced Charge Injection into a Single Conjugated Polymer Chain

Bolinger, Joshua C.; Lee, Kwang Jik; Palacios, Rodrigo E.; Barbara, Paul F.

doi:10.1021/jp804901s

Cited by 16 publications

(28 citation statements)

References 64 publications

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“…[9][10][11] Single molecules (SM) have also been used as probes of conduction and of exciton dynamics in organic semiconductors. [12][13][14][15] However, because of stringent requirements for the good fluorophores for the SMFS (which include high fluorescence quantum yield and high photostability), studies of local nanoenvironment and its effect on photophysics of organic semiconductors have been limited to a handful of materials. In this paper, we discuss high-performance functionalized organic semiconductor materials which are suitable for systematic studies of photophysics which includes charge and energy transfer, both on the macroscopic (device) level and at nanoscales, down to the SM level.…”

Section: -8mentioning

confidence: 99%

Photophysics of organic semiconductors: from ensemble to the single-molecule level

et al. 2015

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We present photophysical properties of functionalized anthradithiophene (ADT) and pentacene (Pn) derivatives, as well as charge and energy transfer properties of donor-acceptor (D/A) pairs of these derivatives. All molecules studied were fluorescent and photostable enough to be imaged on the single-molecule level in a variety of polymeric and in a functionalized benzothiophene (BTBTB) crystalline host using room-temperature widefield epifluorescence microscopy. Flexibility of functionalization of both guest (ADT, Pn) and host (BTBTB or polymer) molecules can be used for systematic studies of nanoscale morphology and photophysics of D/A organic semiconductor bulk heterojunctions, as well as in applications relying on FRET, using single-molecule fluorescence microscopy.

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Section: -8mentioning

confidence: 99%

Photophysics of organic semiconductors: from ensemble to the single-molecule level

et al. 2015

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“…Based on a charge injection device, developed by Bolinger et al, 24 we performed SMS measurements on poly[2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylene-vinylene] (MEH-PPV) and extracted several observables simultaneously during repeated quenching of the PL: (i) PL intensity, (ii) PL lifetime, (iii) PL emission wavelength and (iv) PL photon statistics. We find that upon charge injection the PL intensity drops within several seconds towards a plateau.…”

mentioning

confidence: 99%

“…25 suggesting that an equilibrium is reached between charge injection and extraction. 24 Upon switching the bias to -3V after 10s, the holes are extracted and the PL signal recovers instantaneously. This switching process is reproducible over many cycles facilitating the spectroscopic investigation of the quenched state in conjugated polymers by controlled injection of charges.…”

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confidence: 99%

Impact of charge carrier injection on single-chain photophysics of conjugated polymers

Hofmann

Vogelsang

Lupton

2016

Applied Physics Letters

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Charges in conjugated polymer materials have a strong impact on the photophysics and their interaction with the primary excited state species has to be taken into account in understanding device properties. Here, we employ single-molecule spectroscopy to unravel the influence of charges on several photoluminescence (PL) observables. The charges are injected either stochastically by a photochemical process, or deterministically in a hole-injection sandwich device configuration. We find that upon charge injection, besides a blue-shift of the PL emission and a shortening of the PL lifetime due to quenching and blocking of the lowest-energy chromophores, the non-classical photon arrival time distribution of the multichromophoric chain is modified towards a more classical distribution. Surprisingly, the fidelity of photon antibunching deteriorates upon charging, whereas one would actually expect the number of chromophores to be reduced. A qualitative model is presented to explain the observed PL changes. The results are of interest to developing a microscopic understanding of the intrinsic charge-exciton quenching interaction in devices.

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“…Despite the use of a CBP/ MEH-PPV heterojunction that would be expected to exhibit energetically favorable thermal hole injection, no injection was observed in the dark under positive bias as described in previous papers. [9][10][11] This result suggests that the effective E HOMO of single-conjugated polymer chains is actually lower than the bulk material, due perhaps to environmental or conformational effects.…”

Section: Fv-sms Data Vs Bias Scan Rate and Laser Excitation Powermentioning

confidence: 99%

Factors Controlling Hole Injection in Single Conjugated Polymer Molecules

et al. 2009

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New insights on the molecular level details of the recently reported light-assisted injection of positive charge into single conjugated polymer chains are reported. Extensive new fluorescence-voltage single molecule spectroscopy (FV-SMS) measurements were performed on single chains of the archetypical conjugated polymer MEH-PPV embedded in a capacitor device to complement previous studies of the influence of the bias scan rate and optical excitation intensity. The use of a vacuum microscope allowed for the precise control of the device atmosphere, demonstrating the influence of triplet states in the MEH-PPV on the FV-SMS modulation. For identical device conditions, little variation was observed in the rate and yield of charging from molecule to molecule. Through the use of thicker supporting matrices and insulating polymer "blocking layers", it was determined that good electrical contact between the hole transport layers and the single molecules was necessary for charge injection. The results demonstrate the complexity of charge transfer processes at the interface of organic semiconductors and highlight the ability of single molecule methods to advance the understanding of such processes at the nanoscale.

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Detailed Investigation of Light Induced Charge Injection into a Single Conjugated Polymer Chain

Cited by 16 publications

References 64 publications

Photophysics of organic semiconductors: from ensemble to the single-molecule level

Photophysics of organic semiconductors: from ensemble to the single-molecule level

Impact of charge carrier injection on single-chain photophysics of conjugated polymers

Factors Controlling Hole Injection in Single Conjugated Polymer Molecules

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