Enhanced photoconductivity and trapping rate through control of bulk state in organic triphenylamine-based photorefractive materials

Tsujimura, Sho; Fujihara, Takashi; Sassa, Takafumi; Kinashi, Kenji; Sakai, Wataru; Ishibashi, Koji; Tsutsumi, Naoto

doi:10.1016/j.orgel.2014.09.032

Cited by 9 publications

(7 citation statements)

References 39 publications

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“…Therefore, the fastest response time in the 55 wt % TPAOH composites was due to the enhancement of the charge mobility caused by TPAOH. Finally, it should be noted that similar decay rates found after the second plateaus in Figure 7b suggest that TPAOH showed less influence on deep trapping 22 and the deep trap sites originated from PDAA itself.…”

Section: ■ Results and Discussionsupporting

confidence: 57%

“…Photocurrent measurement has been demonstrated to be a useful technique for understanding the charge transportation processes in PR materials. Deep or shallow traps were detected by observing the shape of the transient photocurrent curves under pumping beam illumination. − In previous studies, , the existence of deep traps caused by NLO chromophores or plasticizers was revealed from the transient photocurrent measurement, considering the HOMO energy levels.…”

Section: Introductionmentioning

confidence: 99%

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Triphenylamine-Based Plasticizer in Controlling Traps and Photorefractivity Enhancement

Giang

Sassa

Fujihara

et al. 2021

ACS Appl. Electron. Mater.

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A video rate operation (30 Hz) with more than 80% diffraction efficiency and net gain of 89 cm −1 was reported in a photorefractive (PR) composite based on poly((4-diphenylamino)benzyl acrylate) (PDAA). A diffraction efficiency of 60% was attained at 60 Hz. To reveal the mechanism behind such highperformance, transient photocurrent measurements were performed. The investigation clearly showed the importance of the (4-(diphenylamino)phenyl)methanol (TPAOH) plasticizer in the charge transport process of the PR composite. The function of TPAOH was demonstrated as a normal plasticizer, as well as an effective photoconductivity enhancement factor of the composite. The analysis of the shapes of the transient photocurrent curve with two trapping sites revealed that TPAOH strongly assisted charge transport in PDAA. The response time of the PR composite was improved by increasing the TPAOH concentration and suppressing the shallow trapping effect. In contrast, the reference 2,4,6-trimethyl-N,N-diphenylaniline (TAA) plasticizer was found to significantly suppress the photocurrent (up to 100 times) compared to that of the TPAOH samples. The replacement of TPAOH by TAA degraded the response time of the diffraction beam. This was attributed to the low-scattering effect caused by the TAA. The study revealed that the deep and shallow traps originate from the PDAA polymer.

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Section: ■ Results and Discussionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Triphenylamine-Based Plasticizer in Controlling Traps and Photorefractivity Enhancement

Giang

Sassa

Fujihara

et al. 2021

ACS Appl. Electron. Mater.

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“…Traps have been extensively studied in photorefractive (PR) materials, ,− as in these materials traps are a critical part of the materials design (Section ). ,, In particular, they determine the capability of the material to store charge, which establishes the material’s utility for particular PR applications.…”

Section: Charge Trapping and Recombinationmentioning

confidence: 99%

Organic Optoelectronic Materials: Mechanisms and Applications

2016

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Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.

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“…In PR polymers, photoconductive plasticizers such as ECZ, 15,39,44,62,63 carbazoylethylpropionate (CzEPA), 44,52,91 TPA, 62,63 2,4,6-trimethylphenyl-diphenylamine (TAA) 41,42 and (4-(diphenylamino)phenyl)methanol (TPAOH) 64 have been commonly used. Photoconductive plasticizers with long alkyl chains, such as 9-(2-ethylhexyl)carbazole (EHCz), 92 have also been used. Other common plasticizers, such as BBP, 43 93,94 are often used.…”

Section: Plasticizersmentioning

confidence: 99%

Molecular design of photorefractive polymers

Tsutsumi

2016

Polym J

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This review article describes the current state-of-the-art research on organic photorefractive polymer composites. A historical background on photorefractive materials is first introduced and is followed by a discussion on the opto-physical aspects and the mechanism of photorefractivity. The molecular design of photorefractive polymers and organic compounds is discussed, followed by a discussion on optical applications of the photorefractive polymers. Polymer Journal (2016) 48, 571-588; doi:10.1038/pj.2015.131; published online 27 January 2016 BACKGROUND In this report, the molecular design of organic photorefractive (PR) polymers is reviewed. Organic PR polymers are materials that possess both electro-optical and photoconductive properties. Research on photoconductive polymers, whose pioneering polymer is poly(N-vinyl carbazole) (PVK, PVCz), began in the 1960s. From the 1980s, research on organic nonlinear optical (NLO) materials has been widely conducted in the fields of organic electro-optics and optical nonlinearity. From the 1990s, new technology using organic photorefractivity combined with photoconductive and electro-optical properties was introduced in the field of organic semiconducting materials, 1 and organic light-emitting diodes 2-6 and organic fieldeffect transistors 7 were also debuted in this field. At the same time, the interest of researchers also turned toward the development of organic photovoltaic cells and organic solar cells. [8][9][10][11] The transport of charge carriers through photoconductive manifolds is a common phenomenon found in PR, organic light-emitting diode or organic photovoltaic materials. Thus, the development of materials in each field is expected to merge together to trigger the development of novel materials.The PR effect is a well-known phenomenon that is observed in materials in which refractive index modulation is induced by the space-charge field that results from the redistribution of positive and negative charge carriers separated through photo-excitation. 12 This phenomenon was first reported in inorganic crystals of lithium niobate (LiNbO 3 ) and lithium tantalate (LiTaO 3 ) and was observed through heterogeneous optically induced refractive indices in 1966. 13 Since then, the PR effect has extensively been investigated in many inorganic crystals, and theoretical approaches have been established to explain this phenomenon. 14 In 1991, 1 the first study of PR polymers reported a low diffraction efficiency of 10 −3 to 1% and a small optical gain of 0.33 cm À1 . In 1994, 15 a high diffraction efficiency of 86% (the remaining 14% was attributed to optical losses) and a large optical gain exceeding 200 cm À1 was reported in photoconductive PVK-based PR composites. Over the past two decades, many featured review articles [16][17][18][19][20][21][22][23][24][25][26][27] and book

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Enhanced photoconductivity and trapping rate through control of bulk state in organic triphenylamine-based photorefractive materials

Cited by 9 publications

References 39 publications

Triphenylamine-Based Plasticizer in Controlling Traps and Photorefractivity Enhancement

Triphenylamine-Based Plasticizer in Controlling Traps and Photorefractivity Enhancement

Organic Optoelectronic Materials: Mechanisms and Applications

Molecular design of photorefractive polymers

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