Impact of UV‐Visible Light on the Morphological and Photochemical Behavior of a Low‐Bandgap Poly(2,7‐Carbazole) Derivative for Use in High‐Performance Solar Cells
Aurélien TournebizePierre‐Olivier BussièrePascal Wong‐Wah‐ChungSandrine ThériasAgnès RivatonJean‐Luc GardetteSerge BeaupréMario Leclerc
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Abstract This paper reports on the photochemical behavior upon exposure to UV‐visible light of a poly(2,7‐carbazole) derivative for use in high‐performance solar cells. Poly[ N ‐9′‐hepta‐decanyl‐2,7‐carbazole‐ alt ‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT) is one of a relatively large class of push‐pull carbazole‐based copolymers that have been synthesized to better harvest the solar spectrum. The 2,7‐carbazole building block of PCDTBT is also used with different electron‐accepting units in a large variety of low‐band‐gap polymers. The photochemical and morphological behavior of PCDTBT thin films is investigated from the molecular scale to the nanomechanical properties. The photo‐oxidation mechanism is shown to be governed by chain‐scission and cross‐linking reactions. It results in dramatic evolution of the morphology, roughness and stiffness of thin PCDTBT films. Based on the identification of several photoproducts formed along the macromolecular chains or released into the gas phase, the main pathways of PCDTBT photochemical evolution are discussed. These processes first involve the scission of the C–N bond between the carbazole group and the tertiary carbon atom bearing the alkyl side‐chain. Modifications of the chemical structure of PCDTBT, the evolution of its UV‐visible absorbance, and its nanomechanical properties initiated by light irradiation are shown to be closely related.Keywords:
Carbazole
Visible spectrum
Suitable functionalization of carbazole, namely the combination with other π-electron systems, can modify the π-conjugation behavior, electron-donating ability or fluorescence properties, and then provide various photofunctional materials. Recently, we have synthesized various carbazole-based π-conjugated compounds such as carbazole-based cyclophanes (carbazolophanes), carbazole dimers, carbazole-thiophene dyads and oligomers, and carbazole-fullerene dyads, and studied their properties. This account reviews their synthesis, structures, and properties in detail.
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N-vinylformamid is isomer of acrylamide.The latter can be used to replace copolymerization of N-vinylformamid and its copolymer,reducing second environmental pollution.In different molar ratio's condition,N-vinylformamid and acrylamide can carry out copolymerization before the copolymerization of N-vinylcaprolactam and N-vinylformamid continue.A study of the different monomers and different molar ratio's process of copolymerization is conducted.The copolymer compositions are analyzed and the glass transition temperatures of copolymer are determined.
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Abstract Summary: Carbazole‐based oligomeric and polymeric materials have been studied for almost 25 years for their unique electrical, electrochemical and optical properties. Interestingly, carbazole units can be linked in two different ways leading to either poly( 3,6 ‐carbazole) or poly( 2,7 ‐carbazole) derivatives. While the former class seems to be very interesting for electrochemical and phosphorescence applications, the latter shows very promising optical properties in the visible range for light emitting diodes (LED). The major intrinsic difference between these two classes is the effective conjugation length: poly(2,7‐carbazole) materials having the longer one, due to their poly( p ‐phenylene)‐like structure. Using different synthetic strategies and substitution patterns, the physico‐chemical properties of both classes can be fine‐tuned, leading to high performance materials for a large number electronic applications. Chemical structures for poly(3,6‐carbazole) and poly(2,7‐carbazole) and the materials used as the starting points for their respective syntheses. magnified image Chemical structures for poly(3,6‐carbazole) and poly(2,7‐carbazole) and the materials used as the starting points for their respective syntheses.
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Photoluminescence quantum yield (PLQY) is one of the most important characteristics for organic luminescent materials. However, when carbazole prepared from the lab was compared to that from a commercial source, a remarkable change of PLQY was observed to vary from 37.1% to 69.8%. Taking 9-(4-bromobenzyl)-9H-carbazole (CzBBr) as an example of carbazole derivatives, the PLQYs of CzBBr synthesized from different origins of carbazole were varied from 16.0% to 91.1%. Our studies demonstrated that efficient radiative transition pathways were activated for commercial carbazole based luminescence, leading to a large enhancement in PLQY with fluorescence (from 16.0% to 54.4%) and phosphorescence (from <1% to 36.7%) for CzBBr. These results suggest that the origin of carbazole plays a very important role in determining the optical properties of carbazole derivatives, alerting us to carefully revisit carbazole and its derivatives, especially those with record-high efficiency.
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Since carbazole is benzene-fused pyrrole, incorporation of a carbazole unit into fused porphyrinoids represents interesting possibilities. We have developed carbazole-based porphyrins which exhibited NIR absorption due to the quadruple benzo-fusion moieties. Following the successful synthesis, we have investigated the peripheral and core modifications and ring-expansion of the macrocycle as well as the applications to BODIPY derivatives. Furthermore, we recently synthesized carbazole-based diporphyrins to investigate the intramolecular electronic interactions. Here synthesis and photophysical property of carbazole-based diporphyrins are reported.
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Novel indolo[3,2-b]carbazole derivatives and a chromogenic-sensing 5,12-dihydroindolo[3,2-b]carbazole have been synthesized starting from tetra-tert-butylated 6,12-diaryl-5,11-dihydroindolo[3,2-b]carbazoles, which were prepared via an efficient tert-butylation of 6,12-diaryl-5,11-dihydroindolo[3,2-b]carbazoles.
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A novel of carbazole derivatives containing –Si-OCH 3 groups was successfully synthesized by reaction of carbazole with γ-chloropropylmethyldimethoxysilane. By immobilizing the carbazole derivatives on a glass plate surface through the chemical reaction of -Si-OCH 3 and -Si-OH, a novel photoinduced luminescence film sensors was prepared. The structures of carbazole derivatives was determined by means of 1 H NMR and the film was characterized by fluorescence measurements, contact angle, X-ray photoelectron spectroscopy. The sensing performance of the functionalized glass sensor has been evaluated.
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The properties of copolymerization of D F 3, D 4 were studied . It is a balancing copolymerization with opening cycloes. The produce rate of copolymer and high copolymer is almost constant when it is balanced. As for the discovery of alkaline catalyst, strong catalyst is good for producing copolymer of high molecular weight. Owing to the rise of temperature, the copolymerization speeds up, molecular weight of the copolymer decreases down, and it forms a relationship of ln ~1/ T . At the beginning of copolymerizing, to rise the temperature, and then, to reduce it. The purpose of shortening the time of copolymerization and increasing the molecular weight of copolymer can be got.
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Abstract 13 C NMR chemical shift assignments have been made for a series of 1‐substituted carbazoles, 8‐substituted 1,2,3,4‐tetra‐hydrocarbazoles, 1‐substituted benzo[ a ]carbazoles and 6‐substituted dibenzo‐[ c,g ]carbazoles. Single examples were examined of other classes of substituted carbazoles: 3‐butylcarbazole and its tetrahydro precursor 6‐butyl‐1,2,3,4‐tetra‐hydrocarbazole, 8‐butyl‐ and 8,10‐diethylbenzo[ a ]carbazoles and their 5,6‐dihydro precursors, dibenzo[ a,i ]carbazole and its 5,6,7,8‐tetrahydro precursor, benzo[ c ]carbazole and its 6‐chloro derivatives and 5,6‐dihydrobenzo[ c ]carbazole and 5,6,8,9‐tetrahydrodibenzo[ c,g ]carbazole and their N ‐methyl derivatives. In addition, the N ‐(1‐pyrrolidinomethyl) derivatives of carbazole, 1,2,3,4‐tetrahydrocarbazole, benzo[ c ]carbazole and dibenzo[ c,g ] carbazole were also studied.
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