- New low bandgap molecules based on ethylene-separated benzothiadiazoles: Synthesis and bandgap comparison
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New ethylene-separated benzothiadiazoles were synthesized for the first time by using a facile procedure, and they showed lower bandgaps than the reported benzothiadiazole-containing compounds. This new benzothiadiazole- containing unit could be introduced into the backbone of the π-conjugated small molecules or polymers to develop new materials with a low bandgap that may have potential applications in optoelectronic fields.
- Liu, Yanmei,Lai, Hua,Zhong, Hongliang,Xu, Erjian,Du, Junping,Li, Yuxue,Fang, Qiang
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- Property modulation of benzodithiophene-based polymers via the incorporation of a covalently bonded novel 2,1,3-benzothiadiazole-1,2,4-oxadiazole derivative in their main chain for polymer solar cells
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Two new electron accepting monomers (BBOB and BOB) containing two serially connected different electron deficient units, such as 2,1,3-benzothiadiazole and 1,2,4-oxadiazole, were prepared and copolymerized with electron-rich benzodithiophene (BDT) derivative to afford polymers P(BDT-BBOB) and P(BDT-BOB), respectively. The optical band gaps of P(BDT-BBOB) and P(BDT-BOB) are calculated to be 2.32 eV and 1.99 eV, respectively, and their highest occupied molecular energy levels are determined to be -5.31 eV and -5.27 eV, respectively. Each of the newly synthesized polymers, i.e.P(BDT-BBOB) and P(BDT-BOB), is used as an electron donor, along with PC61BM as an electron acceptor, in the preparation of polymer solar cells (PSCs). The PSCs made with the configuration of ITO/PEDOT:PSS/P(BDT-BBOB) or P(BDT-BOB):PC61BM (1 : 2 wt%)/LiF/Al gave a maximum power conversion efficiency (PCE) of 1.76% and 2.46%, respectively, and the device performance was further improved to 3.31% and 4.21%, respectively, by simply treating the photoactive layer of PSCs with isopropyl alcohol. Overall, the opto-electrical and photovoltaic properties of the two polymers are found to be quite dependent on the configuration of the covalently bonded 2,1,3-benzothiadiazole and 1,2,4-oxadiazole units incorporated in the polymer main chain.
- Agneeswari, Rajalingam,Tamilavan, Vellaiappillai,Song, Myungkwan,Hyun, Myung Ho
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- A low-energy-gap organic dye for high-performance small-molecule organic solar cells
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A novel donor-acceptor-acceptor (D-A-A) donor molecule, DTDCTB, in which an electron-donating ditolylaminothienyl moiety and an electron-withdrawing dicyanovinylene moiety are bridged by another electron-accepting 2,1,3-benzothiadiazole block, has been synthesized and characterized. A vacuum-deposited organic solar cell employing DTDCTB combined with the electron acceptor C70 achieved a record-high power conversion efficiency (PCE) of 5.81%. The respectable PCE is attributed to the solar spectral response extending to the near-IR region and the ultracompact absorption dipole stacking of the DTDCTB thin film.
- Lin, Li-Yen,Chen, Yi-Hong,Huang, Zheng-Yu,Lin, Hao-Wu,Chou, Shu-Hua,Lin, Francis,Chen, Chang-Wen,Liu, Yi-Hung,Wong, Ken-Tsung
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- A rhodanine flanked nonfullerene acceptor for solution-processed organic photovoltaics
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A novel small molecule, FBR, bearing 3-ethylrhodanine flanking groups was synthesized as a nonfullerene electron acceptor for solution-processed bulk heterojunction organic photovoltaics (OPV). A straightforward synthesis route was employed, offering the potential for large scale preparation of this material. Inverted OPV devices employing poly(3-hexylthiophene) (P3HT) as the donor polymer and FBR as the acceptor gave power conversion efficiencies (PCE) up to 4.1%. Transient and steady state optical spectroscopies indicated efficient, ultrafast charge generation and efficient photocurrent generation from both donor and acceptor. Ultrafast transient absorption spectroscopy was used to investigate polaron generation efficiency as well as recombination dynamics. It was determined that the P3HT:FBR blend is highly intermixed, leading to increased charge generation relative to comparative devices with P3HT:PC60BM, but also faster recombination due to a nonideal morphology in which, in contrast to P3HT:PC60BM devices, the acceptor does not aggregate enough to create appropriate percolation pathways that prevent fast nongeminate recombination. Despite this nonoptimal morphology the P3HT:FBR devices exhibit better performance than P3HT:PC60BM devices, used as control, demonstrating that this acceptor shows great promise for further optimization.
- Holliday, Sarah,Ashraf, Raja Shahid,Nielsen, Christian B.,Kirkus, Mindaugas,R?hr, Jason A.,Tan, Ching-Hong,Collado-Fregoso, Elisa,Knall, Astrid-Caroline,Durrant, James R.,Nelson, Jenny,McCulloch, Iain
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- Organic light-emitting material containing benzo[c][1,2,5]thiadiazole derivative receptor structural unit and application
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The invention provides an organic light-emitting material based on a donor-receptor structure of a benzo[c][1,2,5]thiadiazole-4-aldehyde group receptor and a 2-(benzo[c][1,2,5]thiadiazole-4-methylene)malononitrile receptor and application thereof. The organic light-emitting material is a receptor-donor separation system, wherein the receptor is benzo[c][1,2,5]thiadiazole-4-aldehyde or 2-(benzo[c][1,2,5]thiadiazole-4-methylene) malononitrile, and a donor is carbazole and a derivative or benzoxazine and the like. The lowest unoccupied molecular orbital (LUMO) in the material is located in the receptor, and the highest occupied molecular orbital (HOMO) in the material is located in the donor, so that the molecular orbital energy level of the luminescent material can be effectively regulated and controlled through electrical regulation of the receptor structure and the donor. By regulating and controlling the structure of the light-emitting material or the electron donating capability of the donor, the light-emitting color of material molecules can be conveniently regulated. The organic light-emitting material has the characteristic that the light-emitting color is easy to adjust, andcan be used as a light-emitting material for preparing an OLED device.
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- Compounds for organic thin-film solar cells and organic thin-film solar cells
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Provided are compounds with a donor moiety, a first acceptor moiety and a second acceptor moiety, as shown by Formula (I): With the unique molecular design, compounds of Formula (I) can provide a desirable power conversion efficiency. Moreover, this invention also provides organic thin-film solar cells comprising the above-mentioned compounds.
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- Significant improvement of dye-sensitized solar cell performance by small structural modification in π-conjugated donor-acceptor dyes
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Two donor-π-acceptor (D-π-A) dyes are synthesized for application in dye-sensitized solar cells (DSSC). These D-π-A sensitizers use triphenylamine as donor, oligothiophene as both donor and π-bridge, and benzothiadiazole (BTDA)/cyanoacrylic acid as acceptor that can be anchored to the TiO2 surface. Tuning of the optical and electrochemical properties is observed by the insertion of a phenyl ring between the BTDA and cyanoacrylic acid acceptor units. Density functional theory (DFT) calculations of these sensitizers provide further insight into the molecular geometry and the impact of the additional phenyl group on the photophysical and photovoltaic performance. These dyes are investigated as sensitizers in liquid-electrolyte-based dye-sensitized solar cells. The insertion of an additional phenyl ring shows significant influence on the solar cells' performance leading to an over 6.5 times higher efficiency (η = 8.21%) in DSSCs compared to the sensitizer without phenyl unit (η = 1.24%). Photophysical investigations reveal that the insertion of the phenyl ring blocks the back electron transfer of the charge separated state, thus slowing down recombination processes by over 5 times, while maintaining efficient electron injection from the excited dye into the TiO 2-photoanode. Copyright
- Haid, Stefan,Marszalek, Magdalena,Mishra, Amaresh,Wielopolski, Mateusz,Teuscher, Joel,Moser, Jacques-E.,Humphry-Baker, Robin,Zakeeruddin, Shaik M.,Graetzel, Michael,Baeuerle, Peter
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experimental part
p. 1291 - 1302
(2012/07/14)
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