High‐Performance Organic Semiconductors Based on Fluorene–Phenylene Oligomers with High Ionization Potentials

Locklin, Jason; Ling, Mang Mang; Sung, Andrew; Roberts, Mark; Bao, Zhenan

doi:10.1002/adma.200601608

Cited by 66 publications

(43 citation statements)

References 23 publications

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“…[13] The high mobility of the devices confirmed our XRD results and indicated the potential application of DBTDT in OFETs. The FET characteristics of devices deposited at different temperatures are summarized in Table 2.…”

supporting

confidence: 86%

“…[11] Surprisingly, the ionization potential (IP) of DBTDT calculated from the formal potential (E 1/2 ) of the anodic oxidation peak using ferrocene as internal standard was 5.60 eV (assuming that ferrocene has a highest occupied molecular orbital (HOMO) level of -4.8 eV), [12] larger than that of pentacene and PTA. This is one of the highest values for OFET organic semicondutors, [13] implying the good oxidation stability of DBTDT. The HOMO-LUMO (lowest unoccupied molecular orbital) bandgap of DBTDT estimated from the maximum absorption edge of a dilute solution in methylene chloride was about 3.46 eV, much higher than that of pentacene and its analogues.…”

mentioning

confidence: 93%

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High‐Performance Field‐Effect Transistor Based on Dibenzo[d,d′]thieno[3,2‐b;4,5‐b′]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

et al. 2007

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Organic field-effect transistors (OFETs) have attracted much attention as an alternative to conventional silicon-based transistors because they can be potentially fabricated at low cost, in large areas, and on flexible substrates.[1] To realize these advantages of OFETs in commercial application, the performance of OFET devices, such as mobility and stability, should be comparable with that of amorphous hydrogenated silicon. Currently, the best performing p-type organic thin film FET material is pentacene, with mobility above 1.0 cm 2 V -1 s -1and on/off ratio larger than 10 6 .[2] However, pentacene is unstable and degrades rapidly in ambient conditions, because it is subject to photo-induced decomposition, presumably forming transannular endoperoxide or dimeric Diels-Alder adducts. [3] In order to improve the stability, several pentacene analogues, pentathienoacene (PTA) [4] , tetraceno[2,3-b]thiophene (TCT) [5] and anthradithiophene (ADT) [6] were synthesized. These materials indeed showed higher stability than that of pentacene and pretty good FET performance (mobility up to ca. 0.4 cm 2 V -1 s -1 and on/off ratio up to 10 6 ). However, most of these materials suffered from a tedious synthesis and/ or bothersome purification processes, and their stabilities were still far from those needed for practical applications. Dibenzo [d,d′]thieno[3,2-b;4,5-b′]dithiophene (DBTDT, Scheme 1) is an analogue of pentacene that was first synthesized 60 years ago, [7] and no FET properties have been investigated before. DBTDT possesses similar rigid, linear, coplanar conjugated structure to pentacene as well as the same number of delocalized electrons as pentacene. Also, its crystal structure shows a very ordered herringbone packing structure, which is similar to pentacene. [8] More importantly, unlike pentacene, ADT, TCT, and the pentacene derivatives bis(trialkylsilylethynyl)pentacene, [9] DBTDT does not contain the active center for Diels-Alder reaction and endoperoxide adducts. All these merits suggest that DBTDT is a promising candidate for FETs. In this Communication, a new method of synthesizing DBTDT is reported, which avoids the rigorous reaction conditions (high temperature), bothersome purification steps, and low yield that previous methods suffered from. The remarkable high ionization potential, photostability, and FET performance of DBTDT are also presented. DBTDT was prepared from commercially available benzo[b]thiophene, which is abundant as a byproduct in the petroleum industry (Scheme 1). By carefully controlling the reaction temperature, 2 was obtained in high yield.[10] 2 was lithiated with lithium diisopropylamide (LDA) in diethyl ether, and then reacted with copper chloride as a coupling reagent to give 3. Side reactions were avoided by using LDA as lithiation reagent, assuring that pure 3 could be obtained easily. Then DBTDT was synthesized by treatment of 3 with BuLi and bis(phenylsulfonyl)sulfide. DBTDT could be easily purified by flash column chromatography and recrystallization. Its chemical structu...

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confidence: 86%

mentioning

confidence: 93%

High‐Performance Field‐Effect Transistor Based on Dibenzo[d,d′]thieno[3,2‐b;4,5‐b′]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

et al. 2007

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“…This decrease in FET performance in high humidity air is in agreement with observations reported by other groups. [12,38,39] …”

Section: Resultsmentioning

confidence: 99%

Transistor Paint: Environmentally Stable N‐alkyldithienopyrrole and Bithiazole‐Based Copolymer Thin‐Film Transistors Show Reproducible High Mobilities without Annealing

Liu¹,

Zhang²,

Osaka³

et al. 2009

Adv Funct Materials

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New solution processable 4‐(2‐hexyldecan)‐4H‐bisthieno[2,3‐d:3′,2′‐b]pyrrole and 4,4′‐dialkyl‐2,2′‐bithiazole‐based copolymers (PBTzDTPs) are synthesized with excellent FET performance. These novel copolymers have considerable potential in printable electronics as they have high charge carrier mobilities, excellent air stability, good solution processibility, and no requirement for post‐deposition thermal annealing, all requirements for this field of application. The thin film transistors fabricated from PBTzDTPs achieve field effect mobilities as high as 0.14 cm2 V−1 s−1 with current on/off ratios up to 106 without thermal annealing. In addition, the devices exhibit stable performance in air, showing no significant degradation over 60 days. Moreover, the polymers described here provide an excellent example of the systems in which higher mobility performance does not require higher crystalline, long‐range ordered structures. Such a system appears to be particularly promising for rapid fabrication techniques, where kinetic conditions usually prevent the development of long‐range order.

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“…For comparison, the commonly used OTMS-V and OTCS-V films were also prepared using procedures described in the literature. [5,28,[29][30][31] Transistors were completed in top contact geometry with gold source and drain electrodes. The channel length was 50 mm and the width was 1000 mm.…”

Section: Ots Film Preparation and Characterizationmentioning

confidence: 99%

The Role of OTS Density on Pentacene and C₆₀ Nucleation, Thin Film Growth, and Transistor Performance

Virkar

Mannsfeld

et al. 2009

Adv Funct Materials

237

251

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In organic thin film transistors (OTFTs), charge transport occurs in the first few monolayers of the semiconductor near the semiconductor/dielectric interface. Previous work has investigated the roles of dielectric surface energy, roughness, and chemical functionality on performance. However, large discrepancies in performance, even with apparently identical surface treatments, indicate that additional surface parameters must be identified and controlled in order to optimize OTFTs. Here, a crystalline, dense octadecylsilane (OTS) surface modification layer is found that promotes two‐dimensional semiconductor growth. Higher mobility is consistently achieved for films deposited on crystalline OTS compared to on disordered OTS, with mobilities as high as 5.3 and 2.3 cm2 V−1 s−1 for C60 and pentacene, respectively. This is a significant step toward morphological control of organic semiconductors which is directly linked to their thin film charge carrier transport.

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High‐Performance Organic Semiconductors Based on Fluorene–Phenylene Oligomers with High Ionization Potentials

Cited by 66 publications

References 23 publications

High‐Performance Field‐Effect Transistor Based on Dibenzo[d,d′]thieno[3,2‐b;4,5‐b′]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

High‐Performance Field‐Effect Transistor Based on Dibenzo[d,d′]thieno[3,2‐b;4,5‐b′]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

Transistor Paint: Environmentally Stable N‐alkyldithienopyrrole and Bithiazole‐Based Copolymer Thin‐Film Transistors Show Reproducible High Mobilities without Annealing

The Role of OTS Density on Pentacene and C₆₀ Nucleation, Thin Film Growth, and Transistor Performance

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High‐Performance Organic Semiconductors Based on Fluorene–Phenylene Oligomers with High Ionization Potentials

Cited by 66 publications

References 23 publications

High‐Performance Field‐Effect Transistor Based on Dibenzo[d,d′]thieno[3,2‐b;4,5‐b′]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

High‐Performance Field‐Effect Transistor Based on Dibenzo[d,d′]thieno[3,2‐b;4,5‐b′]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

Transistor Paint: Environmentally Stable N‐alkyldithienopyrrole and Bithiazole‐Based Copolymer Thin‐Film Transistors Show Reproducible High Mobilities without Annealing

The Role of OTS Density on Pentacene and C60 Nucleation, Thin Film Growth, and Transistor Performance

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The Role of OTS Density on Pentacene and C₆₀ Nucleation, Thin Film Growth, and Transistor Performance