A low band gap, solution processable oligothiophene with a dialkylated diketopyrrolopyrrole chromophore for use in bulk heterojunction solar cells

Tamayo, Arnold; Dang, Xuan-Dang; Walker, Bright; Seo, Jung Hwa; Kent, Tyler; Nguyen, Thuc‐Quyen

doi:10.1063/1.3086897

Cited by 290 publications

(236 citation statements)

References 16 publications

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“…However, when the carbamate group was replaced with a 2-ethylhexyl solubilising groups (see Figure 1.6g), the material exhibited better stability and with PCBM as acceptor gave a PCE of 3.0% 54 .…”

Section: Non-polymer Donor Materials For Opvmentioning

confidence: 99%

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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Section: Non-polymer Donor Materials For Opvmentioning

confidence: 99%

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

Chandrasekharan¹

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“…7 A high PCE of 3.0% has very recently been demonstrated based on an oligothiophene-diketopyrrolepyrrole and C 71 -PCBM blend. 8 To achieve a high efficiency heterojunction PV cell, it is fundamentally important to develop new p-type pconjugated small molecules with a narrow energy bandgap to harvest more solar radiation and a high charge carrier mobility to transport the photogenerated charges to the electrodes. 9 Oligothiophenes endcapped with triarylamino and dicyanovinyl or tricyanovinyl groups, which exhibit low optical gap absorption and possess a large enough LUMO level offset with the PCBM acceptors for efficient exciton dissociation, have been shown to be useful for a high performance bilayer heterojunction photovoltaic cell.…”

Section: Introductionmentioning

confidence: 99%

“…For application in solution-processable bulk heterojunction PV cells, the materials need to have good solubility and thin-film forming properties. 8 To promote the solution-processable properties of small molecule donors, we have developed a novel series of highly extended oligothiophenes asymmetrically endcapped with a solubilizing triarylamine or triarylamino-substituted dendron and a dicyanovinyl group as a p-type, low-optical-gap semiconductor for solution-processable bulk heterojunction PV cells. The use of a highly extended p-conjugated system not only lowers the optical bandgap and promotes strong p-p stacking of conjugated backbones but also increases the absorption and broadens the absorption spectrum as compared to the lower homologues.…”

Section: Introductionmentioning

confidence: 99%

Solution processable donor–acceptor oligothiophenes for bulk-heterojunction solar cells

et al. 2010

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“…[23][24][25] Recently, we reported several symmetric and unsymmetrical push-pull organic semiconductors containing various donors and acceptors for solution-processed SMOSCs. [26][27][28][29][30][31][32][33][34][35][36] The use of a triarylamine donor substantially stabilized separated holes from excitons, thereby improving the hole carrier transport properties of the material.…”

mentioning

confidence: 99%

Effects of Fused Thiophene Bridges in Organic Semiconductors for Solution-Processed Small-Molecule Organic Solar Cells

Lee

Lee²,

Yun³

2013

Bulletin of the Korean Chemical Society

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Three push-pull organic semiconductors, TPA-Th 3 -MMN (1), TPA-ThTT-MMN (2), and TPA-ThDTT-MMN (3), comprising a triphenylamine donor and a methylene malononitrile acceptor linked by various π-conjugated thiophene units were synthesized, and the effects of the π-conjugated bridging unit on the photovoltaic characteristics of solution-processed small-molecule organic solar cells based on these semiconductors were investigated. Planar bridging units with extended π-conjugation effectively facilitated intermolecular π-π packing interactions in the solid state, resulting in enhanced J sc values of the SMOSCs fabricated with bulk heterojunction films.

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A low band gap, solution processable oligothiophene with a dialkylated diketopyrrolopyrrole chromophore for use in bulk heterojunction solar cells

Cited by 290 publications

References 16 publications

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

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

Solution processable donor–acceptor oligothiophenes for bulk-heterojunction solar cells

Effects of Fused Thiophene Bridges in Organic Semiconductors for Solution-Processed Small-Molecule Organic Solar Cells

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