Investigation of photoexcitations of conjugated polymer/fullerene composites embedded in conventional polymers

Abstract

Investigation of photoexcitations of conjugated polymer/fullerene composites embedded in conventional polymers Brabec, C.J.; Dyakonov, V.; Sariciftci, N.S.; Graupner, W.; Leising, G.; Hummelen, Jan Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. A promising approach to improve the processability of semiconducting polymers is their incorporation into host matrices formed by conventional polymers such as polyethylene ͑PE͒ or polystyrene ͑PS͒. We have characterized the linear optical properties of several guest-host systems by absorption and luminescence measurements and probed the excited states by photoinduced absorption measurements ͑PIA͒ and light induced electron spin resonance ͑LESR͒. The interesting photophysics of conjugated polymer/fullerene donor-acceptor system, showing an ultrafast photoinduced electron transfer and a metastable charge separation in the pristine state, has been investigated in such composites where the photoactive components are further embedded into a conventional polymer matrix. The composition of the blend and the relative concentration of the components are found to strongly influence the photoinduced interaction between the conjugated polymer and the fullerenes ͑C 60 and functionalized fullerenes͒. Photoinduced electron transfer between a soluble polyphenylenevinylene ͑PPV͒ derivative and C 60 is observed in a system with PS as host when the concentration of the both electroactive components is 33%. In diluted composites with PS as matrix we find strong luminescence quenching of the PPV derivative but no electron transfer upon adding C 60 . Dominant photoexcitations in these PS systems are triplet states as follows from intensity dependencies and lifetime measurements. In diluted systems with PE as matrix neither charge transfer nor luminescence quenching has been observed.

Recombination of triplet excitons and polaron pairs in a derived paraphenylene vinylene pentamer

“…The nonconjugated PS, which serves here as a transparent matrix for the Ooct-OPV5 molecules, makes it possible to obtain homogeneous films, and is known to favor charge transfer processes, in contrast to other polymers such as polyethylene. 19 X-band (Ϸ 9.4 GHz͒ ODMR experiments were performed in a Bruker ESP300 spectrometer with an Oxford liquid helium flow cryostat (Tϭ2Ϫ300 K). The sample is on a holder with optical fiber access for optical excitation, and the photoemission is collected through the optical windows of the rectangular cavity and imaged onto a silicon photodetector.…”

“…It is known, for conjugated polymers blended in a PS matrix, that the CT will only occur up to a critical intermolecular distance, after which only the energy transfer will be operative for energy dissipation. 19,31 The formation of aggregates, or crystalline regions, in concentrated blends and in pure polymers, on the other hands, would enable the charge transfer. Note that in ODMR one indirectly detects the resonant microwave transitions between the states of the triplet PPs via their influence on the SE PL intensity.…”

Optical properties of trans-stilbene using semiempirical and time-dependent density functional theory: A comparative study

“…The synthesis and characterization of advanced polymer materials with specific electronic, optical, and magnetic properties represent a major research topic nowadays 1, 2, in view of their numerous applications in, e.g., light‐emitting diodes (LEDs) 3, 4, field‐effect transistors (FETs) 5, 6, antistatic layers 7, sensors 8, and solar cells 9, 10. Up to now, most theoretical studies 11–14 of the optical properties of conjugated and low‐bandgap polymers have been carried out on semiempirical grounds, such as valence effective Hamiltonian (VEH) 15, Pariser–Parr–Pople (PPP) 16, 17, complete 18 and intermediate 19 neglect of differential overlap for spectroscopy (CNDO/S and INDO/S).…”

Optimization of the Electrical Performance of Polymeric Films

“…Moreover, polymers can be deposited as thin films onto a variety of substrates using spinning techniques. The purpose of the present study is to analyze the electrical properties of different composite polymeric films [11][12][13] through extensive laboratory experiments and through numerical optimization. While laboratory experiments have been a natural choice for polymer scientists, recent years have also seen an application of mathematical tools for analyzing the properties.…”