1246949-11-0Relevant academic research and scientific papers
Tuning energy levels of low bandgap semi-random two acceptor copolymers
Zhou, Jinjun,Xie, Sibai,Amond, Emily F.,Becker, Matthew L.
, p. 3391 - 3394 (2013)
A series of low bandgap semi-random copolymers incorporating various ratios of two acceptor units - thienothiadiazole and benzothiadiazole - were synthesized by Pd-catalyzed Stille coupling. The polymer films exhibited broad and intense absorption spectra, covering the spectral range from 350 nm up to 1240 nm. The optical bandgaps and HOMO levels of the polymers were calculated from ultraviolet-visible spectroscopy and cyclic voltammetry measurements, respectively. By changing the ratio of the two acceptor monomers, the HOMO levels of the polymers were tuned from -4.42 to -5.28 eV and the optical bandgaps were varied from 1.00 to 1.14 eV. The results indicate our approach could be applied to the design and preparation of conjugated polymers with specifically desired energy levels and bandgaps for photovoltaic applications.
Copolymers Containing 1-Methyl-2-phenyl-imidazole Moieties as Permanent Dipole Generating Units: Synthesis, Spectroscopic, Electrochemical, and Photovoltaic Properties
Drapa?a, Jakub,Korona, Krzysztof P.,Kulszewicz-Bajer, Irena,Maranda-Niedba?a, Agnieszka,Mech, Wojciech,Nowakowski, Robert,Wielgus, Ireneusz,Wróbel, Zbigniew,Zagórska, Ma?gorzata
, (2022/02/01)
New donor–acceptor conjugated alternating or random copolymers containing 1-methyl-2-phenylbenzimidazole and benzothiadiazole (P1), diketopyrrolopyrrole (P4), or both acceptors (P2) are reported. The specific feature of these copolymers is the presence of a permanent dipole-bearing moiety (1-methyl-2-phenyl imidazole (MPI)) fused with the 1,4-phenylene ring of the polymer main chain. For comparative reasons, polymers of the same main chain but deprived of the MPI group were prepared, namely, P5 with diketopyrrolopyrrole and P3 with both acceptors. The presence of the permanent dipole results in an increase of the optical band gap from 1.51 eV in P3 to 1.57 eV in P2 and from 1.49 eV in P5 to 1.55 eV in P4. It also has a measurable effect on the ionization potential (IP) and electrochemical band gap (EgCV), leading to their decrease from 5.00 and 1.83 eV in P3 to 4.92 and 1.79 eV in P2 as well as from 5.09 and 1.87 eV in P5 to 4.94 and 1.81 eV in P4. Moreover, the presence of permanent dipole lowers the exciton binding energy (Eb) from 0.32 eV in P3 to 0.22 eV in P2 and from 0.38 eV in P5 to 0.26 eV in P4. These dipole-induced changes in the polymer properties should be beneficial for photovoltaic applications. Bulk heterojunction solar cells fabricated from these polymers (with PC71 BM acceptor) show low series resistance (rs), indicating good electrical transport properties. The measured power conversion efficiency (PCE) of 0.54% is limited by the unfavorable morphology of the active layer.
Novel 4,8-benzobisthiazole copolymers and their field-effect transistor and photovoltaic applications
Conboy, Gary,Taylor, Rupert G. D.,Findlay, Neil J.,Kanibolotsky, Alexander L.,Inigo, Anto R.,Ghosh, Sanjay S.,Ebenhoch, Bernd,Krishnan Jagadamma, Lethy,Thalluri, Gopala Krishna V. V.,Sajjad, Muhammad T.,Samuel, Ifor D. W.,Skabara, Peter J.
, p. 11927 - 11936 (2017/11/30)
A series of copolymers containing the benzo[1,2-d:4,5-d′]bis(thiazole) (BBT) unit has been designed and synthesised with bisthienyl-diketopyrrolopyrrole (DPP), dithienopyrrole (DTP), benzothiadiazole (BT), benzodithiophene (BDT) or 4,4′-dialkoxybithiazole (BTz) comonomers. The resulting polymers possess a conjugation pathway that is orthogonal to the more usual substitution pathway through the 2,6-positions of the BBT unit, facilitating intramolecular non-covalent interactions between strategically placed heteroatoms of neighbouring monomer units. Such interactions enable a control over the degree of planarity through altering their number and strength, in turn allowing for tuning of the band gap. The resulting 4,8-BBT materials gave enhanced mobility in p-type organic field-effect transistors of up to 2.16 × 10-2 cm2 V-1 s-1 for pDPP2ThBBT and good solar cell performance of up to 4.45% power conversion efficiency for pBT2ThBBT.
Impact of the alkyl side chains on the optoelectronic properties of a series of photovoltaic low-band-gap copolymers
Biniek, Laure,Fall, Sadiara,Chochos, Christos L.,Anokhin, Denis V.,Ivanov, Dimitri A.,Leclerc, Nicolas,Leveque, Patrick,Heiser, Thomas
, p. 9779 - 9786 (2011/11/13)
The design of novel low-band-gap conjugated polymers with appropriate frontier orbital energy levels and good charge transport is needed to improve the conversion efficiency of organic photovoltaic devices. In this article, we describe the synthesis and structure-property relationships of a series of photovoltaic copolymers with a common conjugated backbone and differing solubilizing side chains. The copolymer optoelectronic properties and the related photovoltaic device performances are reported. Our results clearly show that the side chains have a major impact on the material and device properties. The electronic band gap can be varied by more than 0.3 eV, the charge mobilities by orders of magnitude, and the optimized fullerene content of photovoltaic devices by a factor of 4 by barely changing the side-chain positioning and/or by switching from linear to branched alkyl chains. A power conversion efficiency of 2.7% could be achieved with devices using the most promising polymer.
