- Push-pull thiophene-based small molecules with donor and acceptor units of varying strength for photovoltaic application: Beyond P3HT and PCBM
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Here is reported an expedient synthesis implementing enabling technologies of a family of thiophene-based heptamers alternating electron donor (D) and acceptor (A) units in a D-A′-D-A-D-A′-D sequence. The nature of the peripheral A groups (benzothiadiazole vs. thienopyrrole-dione vs. thiophene-S,S-dioxide) and the strength of the donor units (alkyl vs. thioalkyl substituted thiophene ring) have been varied to finely tune the chemical-physical properties of the D-A oligomers, to affect the packing arrangement in the solid-state as well as to enhance the photovoltaic performances. The optoelectronic properties of all compounds have been studied by means of optical spectroscopy, electrochemistry, and density functional theory calculations. Electrochemical measurements and Kelvin probe force microscopy (KPFM) predicted a bifunctional behaviour for these oligomers, suggesting the possibility of using them as donor materials when blended with PCBM, and as acceptor materials when coupled with P3HT. Investigation of their photovoltaic properties confirmed this unusual characteristic, and it is shown that the performance can be tuned by the different substitution pattern. Furthermore, thanks to their ambivalent character, binary non-fullerene small-molecule organic solar cells with negligible values of HOMO and LUMO offsets were also fabricated, resulting in PCEs ranging between 2.54-3.96%. This journal is
- Marinelli, Martina,Candini, Andrea,Monti, Filippo,Boschi, Alex,Zangoli, Mattia,Salatelli, Elisabetta,Pierini, Filippo,Lanzi, Massimiliano,Zanelli, Alberto,Gazzano, Massimo,Di Maria, Francesca
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p. 11216 - 11228
(2021/09/15)
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- From Red to Green Luminescence via Surface Functionalization. Effect of 2-(5-Mercaptothien-2-yl)-8-(thien-2-yl)-5-hexylthieno[3,4- c]pyrrole-4,6-dione Ligands on the Photoluminescence of Alloyed Ag-In-Zn-S Nanocrystals
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A semiconducting molecule containing a thiol anchor group, namely 2-(5-mercaptothien-2-yl)-8-(thien-2-yl)-5-hexylthieno[3,4-c]pyrrole-4,6-dione (abbreviated as D-A-D-SH), was designed, synthesized, and used as a ligand in nonstoichiometric quaternary nanocrystals of composition Ag1.0In3.1Zn1.0S4.0(S6.1) to give an inorganic/organic hybrid. Detailed NMR studies indicate that D-A-D-SH ligands are present in two coordination spheres in the organic part of the hybrid: (i) inner in which the ligand molecules form direct bonds with the nanocrystal surface and (ii) outer in which the ligand molecules do not form direct bonds with the inorganic core. Exchange of the initial ligands (stearic acid and 1-aminooctadecane) for D-A-D-SH induces a distinct change of the photoluminescence. Efficient red luminescence of nanocrystals capped with initial ligands (λmax = 720 nm, quantum yield = 67%) is totally quenched and green luminescence characteristic of the ligand appears (λmax = 508 nm, quantum yield = 10%). This change of the photoluminescence mechanism can be clarified by a combination of electrochemical and spectroscopic investigations. It can be demonstrated by cyclic voltammetry that new states appear in the hybrid as a consequence of D-A-D-SH binding to the nanocrystals surface. These states are located below the nanocrystal LUMO and above its HOMO, respectively. They are concurrent to deeper donor and acceptor states governing the red luminescence. As a result, energy transfer from the nanocrystal HOMO and LUMO levels to the ligand states takes place, leading to effective quenching of the red luminescence and appearance of the green one.
- Kowalik, Patrycja,Bujak, Piotr,Wróbel, Zbigniew,Penkala, Mateusz,Kotwica, Kamil,Maroń, Anna,Pron, Adam
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p. 14594 - 14604
(2020/10/09)
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- A method for synthesizing DBTPD
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The invention discloses a synthetic method of 1,3-dibromo-5-alkyl-4H-thiophene [3,4-c]-pyrroles-4,6(5H)-dione (DBTPD), which is characterized by comprising the following steps: taking 3,4-thiophene dimethylbenzene anhydride and alkylamine as raw materials, taking toluene as a solvent, reacting for 15-24 hours under 90-130 DEG C and then cooling to room temperature, then adding thionyl bromide and organic base under 0 DEG C, stirring for 1-5 hours under room temperature, and heating to 110-130 DEG C and reacting for 15-24 hours. The method can realize one-step synthesis, further separation and purification of an intermediate are not required; thionyl bromide during a synthesis process has dehydration effect and has effect as a brominating agent, anhydrous organic base is taken as a catalyst, so that usage of strong acid such as concentrated sulfuric acid and trifluoroacetic acid can be avoided, reaction security is greatly increased, and the products yield by the method can reach 90%.
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Paragraph 0033; 0035; 0037
(2017/02/17)
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- Linear side chains in benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c] pyrrole-4,6-dione polymers direct self-assembly and solar cell performance
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While varying the size and branching of solubilizing side chains in π-conjugated polymers impacts their self-assembling properties in thin-film devices, these structural changes remain difficult to anticipate. This report emphasizes the determining role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency. In contrast, we show that for polymers with branched alkyl-substituted BDT motifs, controlling the number of aliphatic carbons in the linear N-alkyl-substituted TPD motifs is a major contributor to improved material performance. With this approach, PBDTTPD polymers were found to reach power conversion efficiencies of 8.5% and open-circuit voltages of 0.97 V in BHJ devices with PC71BM, making PBDTTPD one of the best polymer donors for use in the high-band-gap cell of tandem solar cells.
- Cabanetos, Clement,El Labban, Abdulrahman,Bartelt, Jonathan A.,Douglas, Jessica D.,Mateker, William R.,Frechet, Jean M. J.,McGehee, Michael D.,Beaujuge, Pierre M.
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p. 4656 - 4659
(2013/05/09)
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- Enhanced performance of quasi-solid-state dye-sensitized solar cells by branching the linear substituent in sensitizers based on thieno[3,4-c]pyrrole-4, 6-dione
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Thieno[3,4-c]pyrrole-4,6-dione-based organic sensitizers with triphenylamine (FNE38 and FNE40) or julolidine (FNE39 and FNE41) as electron-donating unit have been designed and synthesized. A linear hexyl group or a branched alkyl chain, the 2-ethylhexyl group, is incorporated into molecular skeleton of the dyes to minimize intermolecular interactions. The absorption, electrochemical, and photovoltaic properties for these sensitizers were then systematically investigated. It is found that the sensitizers have similar photophysical and electrochemical properties, such as absorption spectra and energy levels, owing to their close chemical structures. However, the quasi-solid-state dye-sensitized solar cells (DSSCs) based on the two types of sensitizers exhibit very different performance parameters. Upon the incorporation of the short ethyl group on the hexyl moiety, enhancements in both open-circuit voltage (Voc) and short-circuit current (J sc) are achieved for the quasi-solid-state DSSCs. The Voc gains originating from the suppression of charge recombination were quantitatively investigated and are in good agreement with the experimentally observed Voc enhancements. Therefore, an enhanced solar energy conversion efficiency (I·) of 6.16 %, constituting an increase by 23 %, is achieved under standard AM 1.5 sunlight without the use of coadsorbant agents for the quasi-solid-state DSSC based on sensitizer FNE40, which bears the branched alkyl group, in comparison with that based on FNE38 carrying the linear alkyl group. This work presents a design concept for considering the crucial importance of the branched alkyl substituent in novel metal-free organic sensitizers. Copyright
- Feng, Quanyou,Zhang, Weiyi,Zhou, Gang,Wang, Zhong-Sheng
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p. 168 - 177
(2013/02/25)
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