Measurement of the S0–T1 energy gap in poly(2-methoxy,5-(2′-ethyl-hexoxy)–p-phenylenevinylene) by triplet–triplet energy transfer

Monkman, Andrew P.; Burrows, Hugh D.; Miguel, Maria G.; Hamblett, I.; Navaratnam, S.

doi:10.1016/s0009-2614(99)00541-2

Cited by 92 publications

(73 citation statements)

References 32 publications

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“…Transient absorption difference spectra were observed using a Xenon source and gated diode array or photomultiplier for detection. General details have been reported [22,28].…”

Section: Methodsmentioning

confidence: 99%

“…Pulse radiolysis of an argon-saturated solution of this polymer (25 mg/l) in benzene in the presence of biphenyl leads to initial formation of an absorption at 360 nm assigned to the biphenyl triplet state [29,31]. The decay of this is accompanied by the grow-in of a new absorption at 830 nm, assigned to the MEH-PPV triplet state [22], and corresponding bleaching of the ground state MEH-PPV absorption at 530 nm. These spectral changes are illustrated in Fig.…”

Section: Triplet State Studiesmentioning

confidence: 99%

“…The ground-state absorption spectrum shows no such structure [33], suggesting that the triplet state has a more localised character than the ground state. The species responsible for this new absorption is strongly quenched by molecular oxygen in a bimolecular process k 2:5 £ 10 9 M 21 s 21 : This has been shown by time-resolved luminescence measurements to lead to formation of singlet molecular oxygen, with F D 0:025 [22], via the energy transfer reaction…”

mentioning

confidence: 91%

“…(200 meV), which is probably associated with CyC stretch modes [22]. The ground-state absorption spectrum shows no such structure [33], suggesting that the triplet state has a more localised character than the ground state.…”

mentioning

confidence: 98%

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Transient absorption spectra of triplet states and charge carriers of conjugated polymers

Miguel

Monkman

Hamblett

et al. 2001

Journal of Molecular Structure

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The use of pulse radiolysis to study transient species in conjugated polymers in solutions is discussed, with particular reference to poly(2-methoxy-5-(2 0 -ethylhexoxy)-p-phenylenevinylene) (MEH-PPV). The excited triplet state is speci®cally generated by energy transfer on radiolysis of benzene solutions in the presence of suitable sensitisers, and its spectrum is reported. The presence of vibronic structure suggests a localised triplet state. By varying the energy of the sensitiser, it is possible to determine the energy of the lowest triplet state. Results are also presented for the triplet±triplet absorptions and energies of ®ve other common p-conjugated polymers. The MEH-PPV triplet absorption, produced on radiolysis, does not increase linearly with either polymer concentration or radiation dose. This is suggested to be due to the presence of multiple triplet excitations on the isolated polymer chains. Intrachain triplet±triplet annihilation is observed, and is seen to lead to delayed¯uorescence. Spectra are also reported for the positive and negative charge carriers of MEH-PPV and the other polymers speci®cally produced by pulse radiolysis of the polymers in chloroform or tetrahydrofuran solutions. q

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“…Transient absorption difference spectra were observed using a Xenon source and gated diode array or photomultiplier for detection. General details have been reported [22,28].…”

Section: Methodsmentioning

confidence: 99%

Section: Triplet State Studiesmentioning

confidence: 99%

mentioning

confidence: 91%

mentioning

confidence: 98%

See 2 more Smart Citations

Transient absorption spectra of triplet states and charge carriers of conjugated polymers

Miguel

Monkman

Hamblett

et al. 2001

Journal of Molecular Structure

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“…In the organic semiconductors, the singlet and triplet excitons are very well resolved with little intermixing [35]. This difference comes about because of the excitonic nature of the fundamental excited states of the organic emitters and the large electron correlation energies of the molecules [36,37]. Since the electron and hole are tightly bound with large exciton binding energy [38][39][40], singlet excitons are spatially localized and so their exchange energy is large, whereas for the triplet excitons the electron and hole are in orthogonal orbital's so the triplet excitons have a zero exchange term [41,42].…”

Section: Introductionmentioning

confidence: 99%

Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

Monkman

2013

ISRN Materials Science

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A potential major drawback with organic light-emitting devices, (OLEDs) is the limit of 25% singlet exciton production through spin-dependent charge recombination. Recent device results, however, show that this limit does not hold and far higher efficiencies can be achieved in purely fluorescent-based systems (Wohlgenannt et al. (2012)). Here, the various routes by which triplet excitons can generate singlet states are discussed and their relative contributions to the overall electroluminescence yield are given. The materials requirements to obtain maximum singlet production from triplet states are discussed. These triplet contributions can give very high device yields for fluorescent emitters, which in the case of blue devices can be highly advantageous. Further, new devices architectures open up which are simple and have intrinsically low turn on voltages, ideal for large-area OLED lighting applications.

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Transfer Processes in Semiconducting Polymer–Porphyrin Blends

et al. 2001

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The role played by triplet excitons in polymer‐based LEDs can be analysed by examining the behavior of the excitons in host polymers in a variety of host–guest polymer blend systems (the guest is a porphyrin such as that shown in the Figure) reported here. Charge and energy transfer at heterojunctions in OLEDs depends on these excitons, so an improved understanding of these processes should enable device performance to be improved.

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Measurement of the S0–T1 energy gap in poly(2-methoxy,5-(2′-ethyl-hexoxy)–p-phenylenevinylene) by triplet–triplet energy transfer

Cited by 92 publications

References 32 publications

Transient absorption spectra of triplet states and charge carriers of conjugated polymers

Transient absorption spectra of triplet states and charge carriers of conjugated polymers

Singlet Generation from Triplet Excitons in Fluorescent Organic Light-Emitting Diodes

Transfer Processes in Semiconducting Polymer–Porphyrin Blends

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