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Journal ArticleDOI

Influence of molecular weight of polymer dielectric on the photo-response of solution-processed OFETs

TL;DR: In this paper, the crucial role of molecular weight of the polymer dielectric in regulating the electrical performance and photo-response of TIPS-pentacene OFETs has been explored using poly(vinyl alcohol) (PVA) as the polymer layer.
About: This article is published in Polymer.The article was published on 2021-05-14. It has received 4 citations till now. The article focuses on the topics: Organic field-effect transistor & Vinyl alcohol.
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Journal ArticleDOI
TL;DR: A binary system comprising both an organic semiconductor and a polymer additive has attracted extensive research interests due to great potential for high-performance, solution-processable electronic devices on flexible substrates as discussed by the authors .
Abstract: A binary system comprising both an organic semiconductor and a polymer additive has attracted extensive research interests due to great potential for high-performance, solution-proccessable electronic devices on flexible substrates. The...

11 citations

Journal ArticleDOI
TL;DR: In this paper , the authors used gelatin, a natural biopolymer gate dielectric, and TIPS-pentacene as an organic semiconductor to achieve a low leakage current and low-voltage operation.
Abstract: Organic field-effect transistors (OFETs) have opened up new possibilities as key elements for skinlike intelligent systems, due to the capability of possessing multiple functionalities. Here, multifunctional OFET devices based on gelatin, a natural biopolymer gate dielectric, and TIPS-pentacene as an organic semiconductor are extensively explored. Gelatin is combined with a thin high-k HfO2 dielectric layer deposited by atomic layer deposition (ALD) to achieve a low leakage current and low-voltage operation. The natural biopolymer offers a better semiconductor:dielectric interface, leading to better charge conduction in the devices, along with an enhancement of sensing capabilities giving additional functionality. These fabricated flexible OFET devices exhibit excellent electrical characteristics with a high field-effect mobility reaching over 2 cm2/(V s) (extracted with Ci at 1 kHz), a low subthreshold swing (SS) of ∼200 mV/dec, and a high current on–off (Ion/Ioff) ratio at a low operating voltage of −5 V with excellent electrical and mechanical stability. Moreover, circuit and multiparameter sensing capabilities for visible and UV light, as well as for humidity and breath rate, have been successfully demonstrated for these devices. Our results indicate that these multifunctional OFET devices can open up a plethora of opportunities for practical applications such as real-time health and environmental monitoring.

10 citations

Journal ArticleDOI
TL;DR: In this paper , the effects of polystyrene (PS), poly (vinyldifluoride) (PVDF), polyvinylphenyl (PVP) blended with poly (methylmethacrylate) (PMMA) on the properties of insulating layers were studied.
Abstract: Organic field effect transistors based on blended polymer insulators were fabricated. The effects of polystyrene (PS), poly (vinyldifluoride) (PVDF) and poly (vinylphenyl) (PVP) blended with poly (methylmethacrylate) (PMMA) on the properties of insulating layers were studied. The PMMA:PS films have spherical grains, the PMMA:PVP films exhibit porous pit morphology, and the PMMA:PVDF films still show plane morphology. The morphology of insulating layers can affect the crystallization of organic semiconductors. Meanwhile, the performance of OFET devices indicates that polymer doping decreases the threshold voltage of devices. When the mass ratio of PMMA:PVDF is 10:5, the threshold voltage of OFET devices is about −14.7 V, which is significant lower than that of pure PMMA devices. This is attributed to the larger capacitance and lower roughness of the insulating layers. Therefore, it is a convenient and effective method to optimize the threshold voltage of OFET devices by applying blended polymer insulating layers.

1 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of polystyrene (PS), poly (vinyldifluoride) (PVDF), polyvinylphenyl (PVP) blended with poly (methylmethacrylate) (PMMA) on the properties of insulating layers were studied.
Abstract: Organic field effect transistors based on blended polymer insulators were fabricated. The effects of polystyrene (PS), poly (vinyldifluoride) (PVDF) and poly (vinylphenyl) (PVP) blended with poly (methylmethacrylate) (PMMA) on the properties of insulating layers were studied. The PMMA:PS films have spherical grains, the PMMA:PVP films exhibit porous pit morphology, and the PMMA:PVDF films still show plane morphology. The morphology of insulating layers can affect the crystallization of organic semiconductors. Meanwhile, the performance of OFET devices indicates that polymer doping decreases the threshold voltage of devices. When the mass ratio of PMMA:PVDF is 10:5, the threshold voltage of OFET devices is about -14.7 V, which is significant lower than that of pure PMMA devices. This is attributed to the larger capacitance and lower roughness of the insulating layers. Therefore, it is a convenient and effective method to optimize the threshold voltage of OFET devices by applying blended polymer insulating layers.

1 citations

References
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Journal ArticleDOI
TL;DR: This review suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto -electronic switch and memory.
Abstract: While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory.

1,081 citations

Journal ArticleDOI
TL;DR: In this article, the effect of hydroxyl groups on the electrical properties of pentacene-based organic thin film transistors (OTFTs) was investigated and it was confirmed that large hysteresis usually observed in OTFT devices was strongly related to the hydroxy bonds existing inside of polymeric dielectrics and could be reduced by substituting with cinnamoyl groups.
Abstract: Polymeric dielectrics having different ratios of hydroxyl groups were intentionally synthesized to investigate the effect of hydroxyl groups on the electrical properties of pentacene-based organic thin film transistors (OTFTs). Large hysteresis usually observed in OTFT devices was confirmed to be strongly related to the hydroxyl bonds existing inside of polymeric dielectrics and could be reduced by substituting with cinnamoyl groups. Although the hydroxyl groups deteriorate the capacitance-voltage characteristics and gate leakage current densities, exceptionally high hole mobility (5.5cm2V−1s−1) could be obtained by increasing the number of hydroxyl groups, which was not caused by the improvement of pentacene crystallinity but related to the interface characteristics.

338 citations

Journal ArticleDOI
TL;DR: In this paper, Fourier transform infrared spectroscopy (FTIR) spectra of PVA hydrogel samples showed the absorption regions of the specific chemical groups associated with poly(vinyl alcohol) (-OH, -CO, -CH2) and PVA/GA confirming the formation of crosslinked hydrogels (duplet -CH).
Abstract: Polyvinyl alcohol (PVA), PVA crosslinked with glutaraldehyde hydrogels (PVA/GA), PVA with tetraethylorthosilicate (PVA/TEOS) and PVA/GA/TEOS hybrids with recombinant MPB70 protein (rMPB70) incorporated were chemically characterized by Fourier transform infrared spectroscopy (FTIR). FTIR spectra of PVA hydrogel samples showed the absorption regions of the specific chemical groups associated with poly(vinyl alcohol) (-OH, -CO, -CH2) and PVA/GA confirming the formation of crosslinked hydrogel (duplet -CH). It was observed C-H broad alkyl stretching band (n = 2850-3000 cm-1) and typical strong hydroxyl bands for free alcohol (nonbonded -OH stretching band at n = 3600-3650 cm-1), and hydrogen bonded band (n = 3200-3570 cm-1). The most important vibration bands related to silane alcoxides have been verified on FTIR spectra of PVA/TEOS and PVA/GA/TEOS hybrids (Si-O-Si, n = 1080 and n = 450 cm-1; Si-OH, n = 950 cm-1). FTIR spectra of f PVA hydrogel with rMPB70 incorporated have indicated the specific groups usually found in protein structures, such as amides I, II and III, at 1680-1620 cm-1, 1580-1480 cm-1 and 1246 cm-1, respectively. These results have given strong evidence that recombinant protein rMPB70 was successfully adsorbed in the hydrogels and hybrids networks. These PVA based hydrogels and hybrids were further used in immunological assays (Enzyme-Linked Immunosorbent Assay - ELISA). Tests were performed to detect antibodies against rMPB70 protein in serum samples from bovines that were positive in the tuberculin test. Corresponding tests were carried out without PVA samples in microtiter plates as control. Similar results were found for commercially available microplates and PVA based hydrogels and hybrids developed in the present work regarding to immunoassay sensitivity and specificity response.

285 citations

Journal ArticleDOI
TL;DR: A TIPS-pentacene/PalphaMS blend active layer is prepared with superior performance characteristics (field-effect mobility, on/off ratio, and threshold voltage) over those of neat TIPS, as well as the solution-processability of technologically attractive bottom-gate/bottom-contact OTFT devices.
Abstract: A comprehensive structural and electrical characterization of solution-processed blend films of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) semiconductor and poly(α-methylstyrene) (PαMS) insulator was performed to understand and optimize the blend semiconductor films, which are very attractive as the active layer in solution-processed organic thin-film transistors (OTFTs). Our study, based on careful measurements of specular neutron reflectivity and grazing-incidence X-ray diffraction, showed that the blends with a low molecular-mass PαMS exhibited a strong segregation of TIPS-pentacene only at the air interface, but surprisingly the blends with a high molecular-mass PαMS showed a strong segregation of TIPS-pentacene at both air and bottom substrate interfaces with high crystallinity and desired orientation. This finding led to the preparation of a TIPS-pentacene/PαMS blend active layer with superior performance characteristics (field-effect mobility, on/off ratio, and threshold voltage)...

246 citations

Journal ArticleDOI
TL;DR: The nanolignin particles when used with polyvinyl alcohol (PVA) increased the thermal stability of nanolignedin/PVA blends more effectively compared to the original lignin/ PVA blends.
Abstract: A new method to prepare nanolignin using a simple high shear homogenizer is presented. The kraft lignin particles with a broad distribution ranging from large micron- to nano-sized particles were completely homogenized to nanolignin particles with sizes less than 100 nm after 4 h of mechanical shearing. The (13) C nuclear magnetic resonance (NMR) and (31) P NMR analysis showed that there were no major changes in the chemical composition between the starting kraft lignin particles and the nanolignin obtained after 4 h of mechanical treatment. The nanolignin particles did not show any change in molecular weight distribution and polydispersity compared to the original lignin particles. The nanolignin particles when used with polyvinyl alcohol (PVA) increased the thermal stability of nanolignin/PVA blends more effectively compared to the original lignin/PVA blends.

181 citations