1025451-57-3Relevant articles and documents
Effects of including electron-withdrawing atoms on the physical and photovoltaic properties of indacenodithieno[3,2-b]thiophene-based donor-acceptor polymers: towards an acceptor design for efficient polymer solar cells
Cai, Ping,Xu, Xiaofeng,Sun, Jiangman,Chen, Junwu,Cao, Yong
, p. 20440 - 20450 (2017)
Three new D-A polymers PIDTT-DTBO, PIDTT-DTBT and PIDTT-DTFBT, using indacenodithieno[3,2-b]thiophene (IDTT) as the electron-rich unit and benzoxadiazole (BO), benzodiathiazole (BT) or difluorobenzothiadiazole (FBT) as the electron-deficient unit, were synthesized via a Pd-catalyzed Stille polymerization. The included electron-withdrawing atoms of the acceptor portion were varied between O, S, and F for tailoring the optical and electrochemical properties and the geometry of structures. Their effects on the film topography, photovoltaic and hole-transporting properties of the polymers were thoroughly investigated via a range of techniques. As expected, the stronger electron-withdrawing BO unit affords red-shifted absorption, low-lying HOMO and LUMO levels for the polymer PIDTT-DTBO. However, it depicts lower hole mobility and a less efficient charge collection in the active layer compared to the polymer PIDTT-DTBT. In addition, degradation of the solubility is observed in the fluorinated polymer PIDTT-DTFBT. As a result, a BHJ PSC (ITO/PEDOT:PSS/polymer:PC71BM/interlayer/Al) fabricated with PIDTT-DTBT attains the best power conversion efficiency (PCE) of 4.91%. These results thus demonstrate the potential effects of electronegative atoms on IDTT-based polymers and the structure-function correlations of such electron-donor materials for efficient PSCs.
Effect of fluorination pattern and extent on the properties of PCDTBT derivatives
Cartwright, Luke,Yi, Hunan,Iraqi, Ahmed
, p. 1655 - 1662 (2016)
Herein, we report the synthesis of a series of fluorinated dithienyl carbazole-alt-benzothiadiazoles (PCDTBT analogues) and the characterisation of their optical, electrochemical, thermal and molecular organisation in the solid state. The polymers were decorated with fluorine on either the benzothiadiazole unit, carbazole unit or both to yield PCDTffBT, PCffDTBT and PCffDTffBT, respectively. The copolymers displayed decomposition temperatures in excess of 350°C. PCDTffBT, PCffDTBT and PCffDTffBT displayed optical band gaps of 1.86, 1.82 and 1.88 eV, respectively. It was speculated this was a consequence of the higher molecular weight of PCffDTBT relative to the other polymers. PCffDTBT and PCffDTffBT displayed shallower HOMO levels relative to PCDTffBT; a consequence of fluorinating the carbazole-donor moiety. XRD studies confirmed that fluorinating the benzothiadiazole-acceptor moiety improves molecular ordering by promoting π-π stacking of polymer backbones in solid state. Interestingly, fluorinating the carbazole-donor unit does not improve π-π stacking of polymer backbones.
Modification of a donor-acceptor photovoltaic polymer by integration of optoelectronic moieties into its side chains
Yu, Lin-Feng,Ge, Cong-Wu,Wang, Jin-Tu,Xiang, Xuan,Li, Wei-Shi
, p. 57 - 66 (2015)
In this study, a strategy to modify photovoltaic properties of a known material by integrating certain optoelectronic moieties in its side chains has been described. Thus, a plenty of single and dendritic carbazole units were introduced into the side chains of poly(2,7-(9,9-dialkyl-fluorene)-alt-5,5′-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)) (PFDTBT), a famous donor-acceptor alternative conjugated polymer, to see what and how they can change the latter optoelectronic properties. It was found that such modifications not only increase the polymer light-harvesting capabilities in the UV region, but also enhance hole mobility in the pure film state. Furthermore, complicated photophysical and photochemical processes, including energy transfer, electron transfer and site-isolation effect, were observed to take place between carbazole units and the PFDTBT conjugated backbone. These factors work comprehensively and finally improve the polymer photovoltaic properties when modified with single carbazole units, but deteriorate when modified with dendritic carbazole units.
Linking design and properties of purine-based donor-acceptor chromophores as optoelectronic materials
Collier, Graham S.,Brown, Lauren A.,Boone, Evan S.,Kaushal, Meesha,Ericson, M. Nance,Walter, Michael G.,Long, Brian K.,Kilbey, S. Michael
, p. 6891 - 6898 (2017/07/22)
Creating new building blocks for donor-acceptor conjugated systems is an important task for continued development of materials for organic electronics. Purines were introduced into small-molecule π-conjugated systems via Stille cross-coupling using stannylated derivatives of benzodithiophene, thiophene, or dithienylbenzothiadiazole to generate a series of "purine-π-purine" chromophores having high thermal stability, long excited-state lifetimes, and high quantum yields. Photophysical and electrochemical property characterization indicate that depending on the choice of a conjugated bridging unit, purines behave as either an electron-donating or an electron-accepting unit in these small-molecule donor-acceptor chromophores. Specifically, while purine chromophores do not exhibit charge transfer character when linked to a thiophene unit, purinyl units act as a weak acceptor when coupled with benzodithiophene and as a weak donor when coupled with dithienylbenzothiadiazole. In addition to fundamental insights into the molecular design of purine-based chromophores and their charge-transfer character, the results and synthetic tailorability of purines suggest that they may be compelling building blocks in conjugated materials for optical and electronic devices and sensors.
