Morphology optimization for achieving air stable and high performance organic field effect transistors

Kumar, Pramod; Sharma, Akanksha; Yadav, Sarita; Ghosh, Subhasis

doi:10.1016/j.orgel.2013.03.027

Cited by 37 publications

(34 citation statements)

References 33 publications

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“…The main advantages of using small molecules is that these can be synthesized in high purity and precision which facilitates high order and often result in high charge carrier field‐effect mobility. When crystallization takes place, especially in the case of single crystals, the tight packing would also improve the durability under ambient conditions . The traditional disadvantage of small molecules is in the required processing which is mostly done through vapor‐phase deposition that is less amendable to low‐cost roll‐to‐roll deposition, which seems to be the ultimate goal for producing organic electronics.…”

Section: Introductionmentioning

confidence: 99%

The Relation Between Molecular Packing or Morphology and Chemical Structure or Processing Conditions: the Effect on Electronic Properties

Kumar

Shivananda

Zaja̧czkowski

et al. 2014

Adv Funct Materials

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In the past few decades, mainly two kind of organic semiconductors, namely small molecules and polymers, have been dealt with. It turns out that the difference between these two categories in terms of charge carrier transport arises from the potentially different morphologies and the molecular packing. There are many studies showing the effect of the chemical structure on the electronic properties. However, in this study, the focus is on the role of processing conditions which is found to be of at least equal importance. To study a range of morphologies and packing in as similar molecules, two systems prepared by “Click”‐type chemistry are chosen, with the major difference between them being the replacement of a flat unit with one that introduces a slight twist to the aromatic skeleton. Through AFM and X‐ray studies, it is shown that the molecule with the potentially flat geometry can exhibit a high degree of π–π stacking, leading to morphologies ranging from polycrystalline to single crystals while the other is always in the amorphous film state. The transport properties are compared using organic field effect transistor (OFETs) in both top and bottom contact configurations.

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Section: Introductionmentioning

confidence: 99%

The Relation Between Molecular Packing or Morphology and Chemical Structure or Processing Conditions: the Effect on Electronic Properties

Kumar

Shivananda

Zaja̧czkowski

et al. 2014

Adv Funct Materials

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“…17 The molecular packing morphology, which can be controlled by growth parameters, was also found to remarkably influence the performance of copper phthalocyanine (CuPc) OTFTs. 18 Simeone et al studied the environmental stability of top contact pentacene OTFTs with different grain sizes of pentacene active layer with a thickness of 30 nm. 19 They concluded the morphology difference influences the hysteresis of transfer characteristics induced by water absorption.…”

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confidence: 99%

“…20,21 It is noticeable, when the amount of grain boundaries at the first monolayer is large; the DV TGD is a rather small proportion comparing the total DV T shift, while for transistors with larger grain size at first monolayer, the contribution of DV TGD becomes significant. In our investigated deposition rate range which covers the common deposition rate of pentacene films grown in S-K growth mode in literatures, 18 the traps in first layer grain boundaries do play a major role in the total DV T shift behaviors. The presented model captures the main factors causing the threshold voltage shift under gate bias stress and produces a quantitative description of the phenomena.…”

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confidence: 99%

Influence of grain size at first monolayer on bias-stress effect in pentacene-based thin film transistors

Zhang

Jiang

2013

Applied Physics Letters

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Threshold voltage shift under applied gate voltage is a key factor characterizing stability of organic thin-film transistors (OTFTs), while the physical mechanism is still controversial. In this study, we systematically examined the initial growth of pentacene polycrystalline films under different growth rates. Bias stress performance of the fabricated pentacene-based OTFTs was found to be highly related to the initial gain size of the pentacene films. Larger grain size at the first deposition layer led to smaller threshold voltage shift. The quantitative correlation can be described by a two-dimensional microscopic mobility model relating to the grains and grain boundaries.

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“…[10][11][12][13] In particular, OPVs have been in the spotlight owing to their low cost, light weight and flexibility.…”

Section: Introductionmentioning

confidence: 99%

Improvement of short circuit current density by intermolecular interaction between polymer backbones for polymer solar cells

Lee

Choi

Jeon

et al. 2016

Polym J

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Benzodithiophene-and quinoxaline (Qu)-based derivatives were used to obtain two kinds of D-π-A-type polymers, poly(diethylhexyloxy benzo dithiophene-dioctyloxy dithiophene diphenyl Qu) (PBDTAQ) and poly(diethylhexyloxy benzo dithiophene-dioctyloxy dithiophene dibenzophenazine (PBDTAFQ), through a Stille coupling reaction. Phenyl (Qu) and fused-phenyl (phenazine, Pz) were introduced in locations 2 and 3, respectively, of Qu derivatives. For the polymer introduced with Pz, the tilt angle (θ 3 ) between the 2,3-carbon and the bonded phenyl side chains of Qu decreased from 44.06°to 0°. As a result, PBDTAFQ displayed a higher absorbance compared with PBDTAQ at the UV-vis absorption spectra in the film state. Also, the intra/intermolecular charge transfer (ICT) peak intensity of 500-700 nm increased relative to the solution peak. Furthermore, the results of the X-ray diffraction measurement suggest that the d π -spacing distance for PBDTAFQ (d π = 3.89 Å) was smaller than that for PBDTAQ (d π = 4.36Å), exhibiting a stronger intermolecular interaction. PBDTAQ showed an edge-on dominant orientation, whereas the PBDTAFQ thin films showed an increase in the face-on structure for crystallinity. As a consequence, PBDTAFQ showed an improved short current density (J SC ) in organic photovoltaic cells. The PBDTAFQ:PC 70 BM blend-based devices that were fabricated exhibited a power conversion efficiency of 3.0% at a 1:5 ratio and reached 3.4% when treated with additive and methanol.

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Morphology optimization for achieving air stable and high performance organic field effect transistors

Cited by 37 publications

References 33 publications

The Relation Between Molecular Packing or Morphology and Chemical Structure or Processing Conditions: the Effect on Electronic Properties

The Relation Between Molecular Packing or Morphology and Chemical Structure or Processing Conditions: the Effect on Electronic Properties

Influence of grain size at first monolayer on bias-stress effect in pentacene-based thin film transistors

Improvement of short circuit current density by intermolecular interaction between polymer backbones for polymer solar cells

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