Photodegradation of poly(methyl methacrylate) by monochromatic light: Quantum yield, effect of wavelengths, and light intensity

Torikai, Ayako; Ohno, Masakuni; Fueki, Kenji

doi:10.1002/app.1990.070410513

Cited by 118 publications

(90 citation statements)

References 7 publications

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“…The UV treatment may modify the PMMA functional end-groups from −CH 3 to −COOH, 13 which results in the changing of charged states near the PMMA surface. Based on these assumptions, the standard ͑with −CH 3 end groups͒ PMMA and UV-treated ͑with −COOH end groups͒ PMMA monomers were estimated using Gaussian 03 with ab initio calculation.…”

Section: Resultsmentioning

confidence: 99%

High Photoresponsivity of Pentacene-Based Organic Thin-Film Transistors with UV-Treated PMMA Dielectrics

Zan

Yen

2008

Electrochem. Solid-State Lett.

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A simple UV-treatment process for poly͑methyl methacrylate͒ ͑PMMA͒ dielectric is proposed to enhance photoresponsivity of pentacene-based organic thin-film transistors. The UV treatment creates excess negatively charged sites on the PMMA dielectric, which makes the device exhibit a large photoinduced current and prolongs persistent conductance recovery. In order to describe time-dependent photoinduced current, double-time constant equations are proposed. Based on time-constant fittings, slow-varied responses are found to be influenced by the UV treatment. The rapid-varied response is independent of gate bias and UV treatment. A plausible model for spatial carrier distribution is discussed and proposed to describe this observed phenomenon. © 2008 The Electrochemical Society. ͓DOI: 10.1149/1.2936224͔ All rights reserved. Organic thin-film transistors ͑OTFTs͒ have received intense attention due to their low cost, light weight, and low-temperature processing compatible with flexible substrates. The integration of OTFTs with other organic devices such as organic light emitting devices and organic solar cells also opens up the field of flexible optoelectronics.1,2 In this field, OTFTs not only act as field-effect transistors, but their application in phototransistors is also important for light detection and photoswitching. However, only a small number of researchers have published works on organic phototransistors. Researchers have observed reversible photocurrent and lightinduced threshold voltage shift.3-5 Pentacene-based OTFTs with Ta 2 O 5 gate dielectrics were also proposed to obtain high photoresponsivity. 4 In this paper, an approach to enhance photoresponsivity of pentacene-based OTFTs is proposed. By using poly͑methyl methacrylate͒ ͑PMMA͒ as the dielectric and applying UVlight treatment, photoresponsivity of OTFTs can be significantly enhanced. By analyzing the response lifetime, the underlying mechanism is investigated carefully. The proposed approach is simple and compatible with the development of all-organic electronics. ExperimentalFirst, the Ni/Pd bilayer was deposited on a glass substrate as a gate electrode. The PMMA was dissolved with a 95 wt % in anisole and was spun onto the gate electrodes. The following was the curing process. The glass substrate was heated with PMMA dielectric on a hot plate at 90°C for 30 min at atmosphere. The solvent was removed and the PMMA was solidified to serve as a gate dielectric. The thickness of the PMMA dielectric was about 360-370 nm. Then, some samples were exposed to UV light ͑Jelight Company, GLS-144 UV Lamp͒, with a wavelength of 175-285 nm and irradiation of 0.043 mW/cm 2 for 90 s. Both the UV-treated PMMA and the untreated ͑standard͒ PMMA dielectrics were transferred into a vacuum chamber for the deposition of 100 nm thick pentacene film and 100 nm thick gold ͑Au͒ electrodes. The device channel width ͑W͒ and length ͑L͒ were 1000 and 100 m, respectively. The illumination system was a combination of a probing bench ͑Cascade microtech, RHM-06͒ and a halogen lamp...

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Section: Resultsmentioning

confidence: 99%

High Photoresponsivity of Pentacene-Based Organic Thin-Film Transistors with UV-Treated PMMA Dielectrics

Zan

Yen

2008

Electrochem. Solid-State Lett.

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“…The quantum yield of main chain scission (Φ cs ) [49] is dependent on intrinsic viscosity of PVC before irradiation (η o ), irradiation time (t), incident intensity (I o ), M V,O , concentration (C) and Avogadro's number (A). The Φ cs was calculated using Equation (6):…”

Section: Determination Of the Average Molecular Weight (M V ) By The mentioning

confidence: 99%

Photostabilizing Efficiency of Poly(vinyl chloride) in the Presence of Organotin(IV) Complexes as Photostabilizers

2016

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Three organotin complexes containing furosemide as a ligand (L), Ph 3 SnL, Me 2 SnL 2 and Bu 2 SnL 2 , were synthesized and characterized. Octahedral geometry was proposed for the Me 2 SnL 2 and Bu 2 SnL 2 , while the Ph 3 SnL complex has trigonal bipyramid geometry. The synthesized organotin complexes (0.5% by weight) were used as additives to improve the photostability of poly(vinyl chloride), PVC, (40 µm thickness) upon irradiation. The changes imposed on functional groups, weight loss and viscosity average molecular weight of PVC films were monitored. The experimental results show that the rate of photodegradation was reduced in the presence of the organotin additives. The quantum yield of the chain scission was found to be low (9.8 × 10 −7 ) when Ph 3 SnL was used as a PVC photostabilizer compared to controlled PVC (5.18 × 10 −6 ). In addition, the atomic force microscope images for the PVC films containing Ph 3 SnL 2 after irradiation shows a smooth surface compared to the controlled films. The rate of PVC photostabilization was found to be highest for Ph 3 SnL followed by Bu 2 SnL 2 and Me 2 SnL 2 . It has been suggested that the organotin complexes could act as hydrogen chloride scavengers, ultraviolet absorbers, peroxide decomposers and/or radical scavengers.

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“…To date, the PMMA photosensitivity under UV radiation is still not completely understood. Early studies reported that the mechanism of photoinduced refractive index increase in PMMA at 325 nm UV radiation was a consequence of photopolymerization of residual monomers [13,14] while other groups demonstrated that the PMMA photodegradation occurred at wavelengths below 320 nm [15,16]. Our recent investigation reported that the main photosensitive mechanism of PMMA-based mPOF irradiated at 325 nm UV light is a competitive process between photodegradation and photopolymerization [17].…”

Section: Introductionmentioning

confidence: 79%

Characterization of Polymer Fiber Bragg Grating With Ultrafast Laser Micromachining

Liu

Cardoso²,

Zhang

et al. 2016

IEEE Photon. Technol. Lett.

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Abstract-We report that the main photosensitive mechanism of poly(methyl methacrylate)-based optical fiber Bragg grating (POFBG) under ultraviolet laser micromachining is a complex process of both photodegradation and negative thermo-optic effect. We found experimentally the unique characteristics of Bragg resonances splitting and reunion during laser micromachining process providing evidence of photodegradation while the mean refractive index change of POFBG was measured to be negative confirming further photodegradation of polymer fiber. The thermal-induced refractive index change of POFBG was also observed by recording the Bragg wavelength shift. Furthermore the dynamic thermal response of the micromachined-POFBG was demonstrated under constant humidity, showing a linear and negative response of around -47.1 pm/°C.

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Photodegradation of poly(methyl methacrylate) by monochromatic light: Quantum yield, effect of wavelengths, and light intensity

Cited by 118 publications

References 7 publications

High Photoresponsivity of Pentacene-Based Organic Thin-Film Transistors with UV-Treated PMMA Dielectrics

High Photoresponsivity of Pentacene-Based Organic Thin-Film Transistors with UV-Treated PMMA Dielectrics

Photostabilizing Efficiency of Poly(vinyl chloride) in the Presence of Organotin(IV) Complexes as Photostabilizers

Characterization of Polymer Fiber Bragg Grating With Ultrafast Laser Micromachining

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