New dithienyl-diketopyrrolopyrrole-based conjugated molecules entailing electron withdrawing moieties for organic ambipolar semiconductors and photovoltaic materials

Yu, Chenmin; Liu, Zitong; Yang, Yang; Yao, Jingjing; Cai, Zhengxu; Luo, Hongjie; Zhang, Guanxin; Zhang, Deqing

doi:10.1039/c4tc01872a

Cited by 28 publications

(17 citation statements)

References 76 publications

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“…The carrier mobilities of both holes and electrons have recently exceeded >1 cm 2 V -1 s -1 , surpassing the carrier mobilities in amorphous silicon semiconductor-based devices. [4][5][6] Most recently-developed highperformance OTFT materials consist of an electron-rich donor moiety (D), 7-10 an electron-deficient moiety (A), [11][12][13][14][15][16] and long alkyl side chains. [17][18][19][20][21][22][23] These donor-acceptor (D-A) conjugated polymers display a highly crystallinity and tight packing in the film state.…”

Section: Introductionmentioning

confidence: 99%

Low-Band-Gap Polymer-Based Ambipolar Transistors and Inverters Fabricated Using a Flow-Coating Method

et al. 2016

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The performances of organic thin film transistors (OTFTs) produced by polymer solution casting are tightly correlated with the morphology and chain-ordering of semiconducting polymer layers, which depends on the processing conditions applied. The slow evaporation of a high boiling point (bp) solvent permits sufficient time for the assembly of polymer chains during the process, resulting in improving the film crystallinity and inducing favorable polymer chain orientations for charge transport. The use of high bp solvents, however, often results in de-wetting of thin films formed on hydrophobic surfaces, such as the commonly used octadecyltrichlorosilane (ODTS)-treated SiO 2 gate dielectric. De-wetting hampers the formation of uniform and highly crystalline semiconducting active channel layers. In this manuscript, we demonstrated the formation of highly crystalline dithienothienyl diketopyrrolopyrrole (TT-DPP)-based polymer films using a flow-coating method to enable the fabrication of ambipolar transistors and inverters.Importantly, unlike conventional spin-coating methods, the flow-coating method allowed us to use high bp solvents, even on a hydrophobic surface, and minimized the polymer solution waste. The crystalline orientations of the TT-DPP-based polymers were tuned depending on the solvent used (four different bp solvents were tested) and the employment of a thermal annealing step. The use of high bp solvents and thermal annealing of the polymer films significantly enhanced the crystalline microstructures in the flowcoated films, resulting in considerable carrier mobility increase in the OTFTs compared to the spin-coated films. Our simple, inexpensive, and scalable flow-coating method, for the first time employed in printing semiconducting polymers, presents a significant step toward optimizing the electrical performances of organic ambipolar transistors through organic semiconducting layer film crystallinity engineering.

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Section: Introductionmentioning

confidence: 99%

Low-Band-Gap Polymer-Based Ambipolar Transistors and Inverters Fabricated Using a Flow-Coating Method

et al. 2016

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“…From 2010 onwards, a very large number of TzTz-based semiconductors (both co-polymers and small-molecule compounds) have been described as photoactive donor materials in organic solar cells, and the corresponding devices have already provided promising results in terms both of power conversion efficiency (up to 7.50 % [83] and 4.18 % [115] for polymers and smallmolecule compounds, respectively) and of stability. [92] In the same period, several unsymmetrical D-π-A compounds, each featuring a thiazolothiazole moiety in the conjugated bridge, were reported to act as photosenzitizers in dye-sensitized solar cells, and a maximum efficiency of 7.71 %, [121] coupled with satisfactory stability of over 1000 h, [122] was observed in the presence of electron-rich propylenedioxythiophene (ProDOT) substituents.…”

Section: Discussionmentioning

confidence: 99%

“…[109] Two TzTz-containing photoactive compounds featuring highly extended conjugated structures and diverse heterocyclic moieties were recently reported: whereas NDT(TTz) 2 had a central electron-rich naphthodithiophene unit and two lateral thi- azolothiazole rings, [110] DTTz-DTBTT was characterized by a central TzTz function flanked by two 2,1,3-benzothiadiazole units; [111] in both cases, such heterocyclic moieties were connected by intermediate thiophene rings (Figure 5). The struc-tures of these two compounds were designed to improve their light-absorption capabilities, resulting in relatively high absorption maxima of 500-587 nm in thin film; despite that, though, the photovoltaic efficiencies remained quite low (1.44-1.64 %), [115] [a] Donor/acceptor ratio in parentheses. indicating that excessive complication of the molecular structure could also be unproductive due to issues with molecular planarity, low hole mobility, and donor-acceptor nanoscale phase separation.…”

Section: Tztz-containing Small Moleculesmentioning

confidence: 99%

“…[114] Finally, the concept of enhancing the light-harvesting properties and tuning the energy levels of TzTz-based semiconductors by introduction of auxiliary electron-withdrawing groups was applied by Liu, Zhang, and co-workers, who prepared diketopyrrolopyrrole-containing compound DPPTT. [115] In this case, the central thiazolothiazole unit was connected to the external conjugated sections through triple bonds, which were installed by means of a Sonogashira coupling (Scheme 12). Compound DPPTT showed ambipolar charge-transport properties, a relatively deep HOMO (due to the presence of the diketopyrrolopyrrole moieties), and a red-shifted absorption maximum (590 nm) coupled with a high molar extinction coefficient.…”

Section: Tztz-containing Small Moleculesmentioning

confidence: 99%

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Photoactive Compounds Based on the Thiazolo[5,4‐d]thiazole Core and Their Application in Organic and Hybrid Photovoltaics

et al. 2015

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Thiazolo[5,thiazoles (TzTzs) are fused bicyclic heteroaromatic compounds characterized by a rigid planar backbone and an extended π-conjugated electronic structure. Although they have been known for many decades, interest in their properties and applications has begun to increase only recently, after their incorporation into a series of active materials used in the field of organic electronics. Recently, the thi-

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“…All the three DPP derivatives showed bipolar mobility with reasonably balanced hole and electron mobilities. The FET mobilities of the OddDPP(ThFl) 2 containing OFETs is amongest highest reported for bipolar non-polymeric DPP based materials 128,129 . 2 , OddDPP(ThFl) 2 and OddDPP(ThBt) 2 under different field-effect transistor conditions.…”

Section: Mobility In An Ofet Configurationmentioning

confidence: 91%

Low optical gap materials for organic solar cells - research and application

Chandrasekharan¹

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In spite of the cost of silicon solar cells decreasing in recent years, there is considerable interest in solar cells with lightweight and flexible forms. Organic semiconductor-based photovoltaic cells (OPVs) have the potential to offer low cost, lightweight and flexible devices. At this stage there is still much to be improved for OPVs as the efficiencies are still lower than their inorganic counterparts. Polymeric materials have been more widely studied than their non-polymeric counterparts. In recent years OPVs polymeric donor materials have emerged with efficiencies reaching 10% with quite a range of materials now providing efficiencies of around 7%. However, the problem with semiconducting polymers is that control of the regioregularity, poly(dispersity), and molecular weight from batch-to-batch is not a simple process. Solution-processable nonpolymeric semiconductors are attractive for opto-electronic applications as they are simpler to synthesise, purify, characterise, and the optical properties can be more easily fine-tuned. In this context, diketopyrrolopyrrole (DPP) based small molecules have shown promising results with devices efficiencies reaching around 5-6%. Key properties of the DPP unit are strong π-π interactions, and suitable and tunable energy levels. These properties have been the main drivers in their use in OPVs.This thesis consist of the synthesis, characterisation, and bulk hetrojunction (BHJ) devices properties of novel DPP(ThAr) 2 non-polymeric materials. Accordingly, a first series of compounds was synthesized with different electron affinity groups such as fluorenone (Fl) [EhDPP(ThFl) 2 and OddDPP(ThFl) 2 ] and benzothiadiazole (Bt) [OddDPP(ThBt) 2 ] attached to the distal ends of a bisthienyl-diketopyrrolopyrrole unit DPP(Th) 2 unit. The 'DPP(ThAr) 2 ' derivatives were synthesised under standard Suzuki-Miyaura cross-coupling or by direct arylation reaction conditions and the rate of the direct arylation reaction was found to be faster than for the Suzuki-Miyaura crosscoupling reactions. The solubility of the compounds was poor when the 2-ethylhexyl (Eh) moiety was used as the solubilising group for DPP(ThFl) 2 . 2-Octyldodecyl (Odd) solubilising groups gave better solubility in chlorinated solvents, which are typically used in OPV fabrication. The three nonpolymeric DPP materials exhibited bipolar charge transport in organic field effect transistors (OFETs), with hole and electron mobility in the order of 10 -2 −10 -3 cm 2 V -1 s -1 , and in a diode architecture OddDPP(ThFl) 2 and OddDPP(ThBt) 2 exhibited mobilities of the order of 10 -4 cm 2 V -1 s -1 for pristine films. In BHJ devices using [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM)as the acceptor, different solvent mixtures were used for device fabrication to achieve the maximum efficiency. The EQE spectra of the blend film suggested that charge generation due to absorption at iii wavelengths longer than 750 nm occurred through the Channel I pathway, and at wavelengths shorter than 750 nm, both Channel I and II ...

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New dithienyl-diketopyrrolopyrrole-based conjugated molecules entailing electron withdrawing moieties for organic ambipolar semiconductors and photovoltaic materials

Cited by 28 publications

References 76 publications

Low-Band-Gap Polymer-Based Ambipolar Transistors and Inverters Fabricated Using a Flow-Coating Method

Low-Band-Gap Polymer-Based Ambipolar Transistors and Inverters Fabricated Using a Flow-Coating Method

Photoactive Compounds Based on the Thiazolo[5,4‐d]thiazole Core and Their Application in Organic and Hybrid Photovoltaics

Low optical gap materials for organic solar cells - research and application

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