Organic FET devices: structure–property relationship in evaporated films of three fluorenone derivatives

Porzio, William; Destri, Silvia; Pasini, Mariacecilia; Giovanella, Umberto; Motta, Tiziano; Iosip, Mariana Dana; Natali, Dario; Sampietro, Marco; Franco, Leopoldo; Campione, Marcello

doi:10.1016/j.synthmet.2004.08.005

Cited by 15 publications

(14 citation statements)

References 23 publications

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“…Suzuki reactions with conventional heating were carried out under nitrogen atmosphere. 2,7-Di(2-thienyl)-9,9-dihexylfluorene (TFTC6), [25] 2,7-di(2-thienyl)-fluoren-9-one (TFOT) [42] and 9,9-bis(4-diphenylaminophenyl)-2,2-dibromofluorene [24] were prepared according to literature. The purity of TFTC6 and TFOT was confirmed by melting point and elemental analysis Poly[(9,9-di-n-hexylfluoren-2,7-diyl)-alt-co-(9,9-bis(4-diphenylaminophenyl)-fluoren-2,7-diyl)] (PFTPA) was prepared as previously reported in ref.…”

Section: Methodsmentioning

confidence: 99%

The Role of Triphenylamine in the Stabilization of Highly Efficient Polyfluorene‐Based OLEDs: A Model Oligomers Study

Pasini¹,

Giovanella²,

Betti³

et al. 2009

ChemPhysChem

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In order to understand the factors responsible for the improved efficiency and stability of organic light-emitting diodes (OLEDs) based on poly(9,9-dioctylfluorene) (PFO) when triphenylamine (TPA) is introduced as lateral fluorene substituent, we synthetize mono-disperse fluorene-thiophene oligomers as model compounds. Their blends with different concentrations of the fluorenone containing oligomer are studied in order to verify if only a reduction of ketonic defect sites or also an impeded energy transfer (ET) towards such sites are responsible for the suppression of the green emission band. We show that the introduction of TPA groups leads specifically both to an antioxidant action and a reduced ET towards residual defect sites, thanks to the environmental micro-encapsulation role played by TPA units surrounding the polymer backbone. As a result, the performances and colour stability of a device fabricated with TPA-substituted PFO (PFTPA) are strongly improved with respect to standard PFO device prepared in the same conditions.

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Section: Methodsmentioning

confidence: 99%

The Role of Triphenylamine in the Stabilization of Highly Efficient Polyfluorene‐Based OLEDs: A Model Oligomers Study

Pasini¹,

Giovanella²,

Betti³

et al. 2009

ChemPhysChem

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“…12 Finally oligomers or polymers comprising the same residues have been reported as quite good candidates for p-and n-type organic field-effect transistor (OFET) materials, displaying significant electron and hole transport. [13][14][15][16] Indeed, the F moiety has been often seen as an irregularity of polyfluorene chains -due to oxidation -resulting in a modified spectral response: namely it decreases its luminescence efficiency, 17,18 yielding a green peak in the emission spectrum. In fact, the F moiety, in contrast to fluorene, is stable to oxidation and is capable of close-packing, resulting from H-bond interactions between adjacent molecules.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterisation of fluorenone–thiophene-based donor–acceptor oligomers: role of moiety sequence upon packing and electronic properties

et al. 2010

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“…The materials were then investigated as Channel I materials. Fluorenone has been previously used as an electron affinity unit in conjunction with thiophene in non-polymeric materials, with the compound showing good charge-carrier mobilities in OFETs 101 . In OPVs, materials compressed of fluorenone coupled with an oligothiophene gave a PCE of 1.2% 102 .…”

Section: Aimsmentioning

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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Organic FET devices: structure–property relationship in evaporated films of three fluorenone derivatives

Cited by 15 publications

References 23 publications

The Role of Triphenylamine in the Stabilization of Highly Efficient Polyfluorene‐Based OLEDs: A Model Oligomers Study

The Role of Triphenylamine in the Stabilization of Highly Efficient Polyfluorene‐Based OLEDs: A Model Oligomers Study

Synthesis and characterisation of fluorenone–thiophene-based donor–acceptor oligomers: role of moiety sequence upon packing and electronic properties

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

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