Light‐Emitting Polythiophenes

Perepichka, Igor F.; Perepichka, Dmitrii F.; Meng, Hong; Wudl, Fred

doi:10.1002/adma.200500461

Cited by 883 publications

(597 citation statements)

References 164 publications

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“…The low PLQE of regioregular P3HT films is something of a mystery, with P3HT in solution exhibiting a PLQE of $30% [15] and regiorandom films a PLQE of 10-15%. While this low PLQE is related to the increase in interchain coupling in regioregular P3HT films, the exact mechanism is not clear, having been attributed to interchain dimer formation [16] and polaron generation. [15] Figure 2 presents the absorption and emission spectra of P3HT:F8TBT blends spin-coated from xylene as a function of annealing temperature.…”

Section: Full Papermentioning

confidence: 93%

Photophysics and Photocurrent Generation in Polythiophene/Polyfluorene Copolymer Blends

McNeill

Abrusci

Hwang

et al. 2009

Adv Funct Materials

114

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Here, studies on the evolution of photophysics and device performance with annealing of blends of poly(3‐hexylthiophene) with the two polyfluorene copolymers poly((9,9‐dioctylfluorene)‐2,7‐diyl‐alt‐[4,7‐bis(3‐hexylthien‐5‐yl)‐2,1,3‐benzothiadiazole]‐2′,2′′‐diyl) (F8TBT) and poly(9,9‐dioctylfluorene‐co‐benzothiadiazole) (F8BT) are reported. In blends with F8TBT, P3HT is found to reorganize at low annealing temperatures (100 °C or below), evidenced by a redshift of both absorption and photoluminescence (PL), and by a decrease in PL lifetime. Annealing to 140 °C, however, is found to optimize device performance, accompanied by an increase in PL efficiency and lifetime. Grazing‐incidence small‐angle X‐ray scattering is also performed to study the evolution in film nanomorphology with annealing, with the 140 °C‐annealed film showing enhanced phase separation. It is concluded that reorganization of P3HT alone is not sufficient to optimize device performance but must also be accompanied by a coarsening of the morphology to promote charge separation. The shape of the photocurrent action spectra of P3HT:F8TBT devices is also studied, aided by optical modeling of the absorption spectrum of the blend in a device structure. Changes in the shape of the photocurrent action spectra with annealing are observed, and these are attributed to changes in the relative contribution of each polymer to photocurrent as morphology and polymer conformation evolve. In particular, in as‐spun films from xylene, photocurrent is preferentially generated from ordered P3HT segments attributed to the increased charge separation efficiency in ordered P3HT compared to disordered P3HT. For optimized devices, photocurrent is efficiently generated from both P3HT and F8TBT. In contrast to blends with F8TBT, P3HT is only found to reorganize in blends with F8BT at annealing temperatures of over 200 °C. The low efficiency of the P3HT:F8BT system can then be attributed to poor charge generation and separation efficiencies that result from the failure of P3HT to reorganize.

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Section: Full Papermentioning

confidence: 93%

Photophysics and Photocurrent Generation in Polythiophene/Polyfluorene Copolymer Blends

McNeill

Abrusci

Hwang

et al. 2009

Adv Funct Materials

114

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“…In this class of polymers, the polythiophenes (PT) are being very exploited because of their good thermal and chemical stability, relative facility of functionalization and chromic properties that have a great potential for applications in technological devices, such as solar cells, electrochromic windows, polymer light-emitting diodes and chemical sensors [2][3][4] . Unsubstituted polythiophene was extensively considered as model for the study of charge transport in conjugated polymers.…”

Section: Introductionmentioning

confidence: 99%

Structural and thermal properties of carboxylic acid functionalized polythiophenes

et al. 2014

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Polythiophenes functionalized with polar groups at the end of side-chain have emerged as an alternative method to obtain good compatibility between this class of conjugated polymers and electron acceptor compounds. The aim is to prevent phase segregation and to improve the efficiency of the polythiophene technological devices. However, homopolymers synthesized from thiophene rings with high polar groups at the end of the side-chain, such as hydroxyl and carboxylic acid groups, are poorly soluble in common volatile organic solvents. We report on a systematic preparation of copolymers of 3-hexylthiophene (HT) and thiophene-3-acetic acid (TAA), using different feed ratios. The chemical structures of the copolymers were confirmed by FTIR and 1 H-NMR. The TAA content in these copolymers were 33, 38 and 54 mol %. HPSEC results did not show any remarkable correlation with TAA contents in the copolymers. In contrast, the thermal analyses showed a decrease in the thermal stability and an increase in rigidity of their backbones, for the copolymers with high amounts of TAA. The solubility and optical property of copolymers were also related to the TAA contents. Thus, the properties of these copolymers can be modulated by a simple control of feed ratio of TAA in the copolymerization.

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“…Polythiophenes are probably one of the most versatile classes of π-conjugated systems within this group of compounds. [1][2][3][4][5] This results, in part, from their unique properties, as demonstrated by their chemical stability and facility for tuning electronic properties through modification of their chemical structure. Various applications of oligo-and polythiophenes are found in modern materials science, such as their use in light emitting diodes, field effect transistors, and electrochromic and photovoltaic devices.…”

Section: Introductionmentioning

confidence: 99%

Spectral and Photophysical Studies on Cruciform Oligothiophenes in Solution and the Solid State

et al. 2006

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The photophysical and spectroscopic properties of a new class of oligothiophene derivatives, designated as cruciform oligomers, have been investigated in solution (room and low temperature) and in the solid state (as thin films in Zeonex matrixes). The study comprises absorption, emission, and triplet-triplet absorption spectra, together with quantitative measurements of quantum yields (fluorescence, intersystem crossing, internal conversion, and singlet oxygen formation) and lifetimes. The overall data allow the determination of the rate constants for all decay processes. From these, several conclusions are drawn. First, in solution, the main deactivation channels for the compounds are the radiationless processes: S 1 ' S 0 internal conversion and S 1 ' T 1 intersystem crossing. Second, in general, in the solid state, the fluorescence quantum yields decrease relative to solution. A comparison is made with the analogous linear R-oligothiophenes, revealing a lower fluorescence quantum efficiency and, in contrast to the normal oligothiophenes, that internal conversion is an important channel for the deactivation of the singlet excited state. Replacement of thiophene by 1,4-phenylene units in the longer-sized cruciform oligomer increases the fluorescence efficiency. The highly efficient generation of singlet oxygen through energy transfer from the triplet state (S ∆ ≈ 1) provides support for the measured intersystem crossing quantum yields and suggests that reaction with this may be an important pathway to consider for degradation of devices produced with these compounds.

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Light‐Emitting Polythiophenes

Cited by 883 publications

References 164 publications

Photophysics and Photocurrent Generation in Polythiophene/Polyfluorene Copolymer Blends

Photophysics and Photocurrent Generation in Polythiophene/Polyfluorene Copolymer Blends

Structural and thermal properties of carboxylic acid functionalized polythiophenes

Spectral and Photophysical Studies on Cruciform Oligothiophenes in Solution and the Solid State

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