Optical spectroscopy of platinum and palladium containing poly-ynes

Wittmann, H. F.; Friend, Richard H.; Khan, Muhammad S.; Lewis, Jack

doi:10.1063/1.467650

Cited by 123 publications

(89 citation statements)

References 17 publications

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“…[82][83][84][85] The metal atom integrated into the polymer backbone can increase the mixing of the first excited singlet and triplet states, leading to higher electroluminescence quantum efficiencies of PLEDs. In contrast, metallated conjugated polymers have rarely been tested as donor materials in bulk-heterojunction solar cells.…”

Section: Metallated Conjugated Polymersmentioning

confidence: 99%

Polymer‐Fullerene Bulk‐Heterojunction Solar Cells

Dennler¹,

Scharber²,

Brabec³

2009

Advanced Materials

3,123

2,461

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Solution‐processed bulk‐heterojunction solar cells have gained serious attention during the last few years and are becoming established as one of the future photovoltaic technologies for low‐cost power production. This article reviews the highlights of the last few years, and summarizes today's state‐of‐the‐art performance. An outlook is given on relevant future materials and technologies that have the potential to guide this young photovoltaic technology towards the magic 10% regime. A cost model supplements the technical discussions, with practical aspects any photovoltaic technology needs to fulfil, and answers to the question as to whether low module costs can compensate lower lifetimes and performances.

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Section: Metallated Conjugated Polymersmentioning

confidence: 99%

Polymer‐Fullerene Bulk‐Heterojunction Solar Cells

Dennler¹,

Scharber²,

Brabec³

2009

Advanced Materials

3,123

2,461

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“…A direct confirmation of the E T value extracted above is the observation of a weak phosphorescence emission, Ph, from the lowest lying triplet state to the singlet ground state [17]. We have succeeded in measuring this emission band in quadrature (Fig.…”

mentioning

confidence: 58%

Photogeneration Action Spectroscopy of Neutral and Charged Excitations in Films of a Ladder-Type Poly(Para-Phenylene)

et al. 1999

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The photogeneration quantum efficiency action spectra of long-lived neutral and charged excitations in films of a ladder-type poly(para-phenylene) were measured. We found that both triplet and polaron action spectra show, in addition to a step function increase at the optical gap, a monotonic rise at higher energies. For triplets this rise is explained by singlet exciton fission into triplet pairs from which the triplet exciton energy in the gap was obtained; this energy was also confirmed by measuring the weak phosphorescence band. For polarons the photogeneration increase at high energies is modeled by a novel hot electron interchain tunneling process. [S0031-9007(99)08980-2] PACS numbers: 78.55. Kz, 72.20.Jv, 78.30.Jw, 78.66.Qn The photogeneration dynamics of singlet excitons and secondary photoexcitations, such as triplets and polarons, in p-conjugated polymers have been usually measured by picosecond transient spectroscopic techniques rather than cw spectroscopies, since their photogeneration processes usually occur in the subnanosecond time domain [1]. On the other hand, the excited states energy levels of these polymers are often measured by cw optical techniques including electroabsorption [2], resonant Raman scattering [3], and by two and three photon nonlinear optical spectroscopies [4]. In this Letter we employ a new version of the cw photomodulation (PM) spectroscopy technique, which is capable of measuring the photogeneration quantum efficiency, h, of long-lived secondary photoexcitations without the need of transient optical techniques. We show that when the PM signal is measured under conditions far from the steady state, then it directly correlates with h; therefore the PM action spectrum (PMAS) measured under these conditions gives the dependence of h on the excitation photon energy, E, i.e., h͑E͒.We have used the PMAS technique to obtain h͑E͒ of singlet and triplet excitons and polarons, respectively, in films of methyl-substituted ladder-type poly(paraphenylene) (mLPPP) [5] shown in Fig. 1, inset. mLPPP is an attractive p-conjugated polymer for blue-light emitting devices [6] due to its high photoluminescence (PL) quantum yield; this is caused, in part, by the intrachain order in the film induced by the planarization of neighboring phenyl rings [7]. mLPPP was chosen as a model polymer because of its reduced inhomogeneity and small defect density [8].For the excitation beam in the PMAS measurements we used either an Ar 1 laser at several discrete E, or a monochromatized xenon lamp beam to continuously vary E between 2 and 4.5 eV. The excitation beam was modulated with a chopper at a frequency, f, between 10 to 4 kHz. A combination of various incandescent lamps, diffraction gratings, optical filters, and solid state detectors was used to span the probe energy (hv) between 0.1 and 3 eV. The PM spectrum as a function ofhv was obtained by dividing the pump beam induced changes in transmission, DT ͑v͒, by the probe transmission T ͑v͒, where Da 2d 21 DT ͞T and d is the film thickness; DT was measu...

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“…Owing to the strong spin-orbital mixing of heavy-metal ions in phosphorescent complexes, both singlet and triplet excitons can be fully utilized [1][2][3][4][5], creating the possibility for electrophosphorescent dye doped devices to reach an internal quantum efficiency of 100%.…”

Section: Introductionmentioning

confidence: 99%