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Youngkyoo Kim - One of the best experts on this subject based on the ideXlab platform.
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efficient deep red light sensing all polymer Phototransistors with p type n type conjugated polymer bulk heterojunction layers
ACS Applied Materials & Interfaces, 2017Co-Authors: Sungho Nam, Hwajeong Kim, D D C Bradley, Jooyeok Seo, Hyemi Han, Youngkyoo KimAbstract:Here we demonstrate deep red light-sensing all-polymer Phototransistors with bulk heterojunction layers of poly[4,8-bis[(2-ethylhexyl)-oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) and poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)] (P(NDI2OD-T2)). The device performances were investigated by varying the incident light intensity of the deep red light (675 nm), while the signal amplification capability was examined by changing the gate and drain voltages. The result showed that the present all-polymer Phototransistors exhibited higher photoresponsivity (∼14 A/W) and better on/off photoswitching characteristics than the devices with the pristine polymers under illumination with the deep red light. The enhanced Phototransistor performances were attributed to the well-aligned nanofiber-like morphology and nanocrystalline P(NDI2OD-T2) domains in the blend films, which are beneficia...
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Efficient Deep Red Light-Sensing All-Polymer Phototransistors with p‑type/n-type Conjugated Polymer Bulk Heterojunction Layers
2017Co-Authors: Sungho Nam, Hwajeong Kim, Jooyeok Seo, Hyemi Han, Donal D. C. Bradley, Youngkyoo KimAbstract:Here we demonstrate deep red light-sensing all-polymer Phototransistors with bulk heterojunction layers of poly[4,8-bis[(2-ethylhexyl)-oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) and poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)] (P(NDI2OD-T2)). The device performances were investigated by varying the incident light intensity of the deep red light (675 nm), while the signal amplification capability was examined by changing the gate and drain voltages. The result showed that the present all-polymer Phototransistors exhibited higher photoresponsivity (∼14 A/W) and better on/off photoswitching characteristics than the devices with the pristine polymers under illumination with the deep red light. The enhanced Phototransistor performances were attributed to the well-aligned nanofiber-like morphology and nanocrystalline P(NDI2OD-T2) domains in the blend films, which are beneficial for charge separation and charge transport in the in-plane direction
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all polymer Phototransistors with bulk heterojunction sensing layers of thiophene based electron donating and thienopyrroledione based electron accepting polymers
Organic Electronics, 2016Co-Authors: Sungho Nam, Hwajeong Kim, D D C Bradley, Youngkyoo KimAbstract:Abstract All-polymer Phototransistors consisting of bulk heterojunction (BHJ) nanolayers of electron-donating (p-type) and electron-accepting (n-type) polymers are attractive candidates for applications such as light-sensing and light-switching devices. Here, we report efficient green-light-sensing all-polymer Phototransistors based on BHJ layers of poly(3-hexylthiophene) (P3HT) and poly[(4,8-bis(2-ethylhexyloxy)-benzo[1,2- b :4,5- b ]-dithiophene)-2,6-diyl- alt -( N -2-ethylhexylthieno[3,4- c ]pyrrole-4,6-dione)-2,6-diyl]] (PBDTTPD) polymers. To understand the Phototransistor characteristics, all devices were exposed to a green monochromatic light (555 nm) with different incident power intensities. The results showed that the P3HT:PBDTTPD (80:20) layer are more advantageous than the pristine P3HT layers in terms of efficient charge separation and transport. The responsivity value of devices with the P3HT:PBDTTPD (80:20) layers reached 33.3 A/W, which is 25 and 28 times higher than those obtained with pristine the pristine P3HT or P3HT:PBDTTPD (60:40) layers. The enhanced device performance of the P3HT:PBDTTPD (80:20) Phototransistors is attributable to an efficient charge separation, prevalent edge-on chain orientation, and relatively smoother surface morphology, which might facilitate improved charge transport in the lateral direction.
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organic Phototransistors with nanoscale phase separated polymer polymer bulk heterojunction layers
Nanoscale, 2011Co-Authors: Hyemin Hwang, Sungho Nam, Hwajeong Kim, D D C Bradley, Youngkyoo KimAbstract:Low-cost detectors for sensing photons at a low light intensity are of crucial importance in modern science. Phototransistors can deliver better signals of low-intensity light by electrical amplification, but conventional inorganic Phototransistors have a limitation owing to their high temperature processes in vacuum. In this work, we demonstrate organic Phototransistors with polymer/polymer bulk heterojunction blend films (mixtures of p-type and n-type semiconducting polymers), which can be fabricated by inexpensive solution processes at room temperature. The key idea here is to effectively exploit hole charges (from p-type polymer) as major signaling carriers by employing p-type transistor geometry, while the n-type polymer helps efficient charge separation from excitons generated by incoming photons. Results showed that the present organic transistors exhibited proper functions as p-type Phototransistors with ∼4.3 A W−1 responsivity at a low light intensity (1 µW cm−2), which supports their encouraging potential to replace conventional cooled charge coupled devices (CCD) for low-intensity light detection applications.
Sungho Nam - One of the best experts on this subject based on the ideXlab platform.
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efficient deep red light sensing all polymer Phototransistors with p type n type conjugated polymer bulk heterojunction layers
ACS Applied Materials & Interfaces, 2017Co-Authors: Sungho Nam, Hwajeong Kim, D D C Bradley, Jooyeok Seo, Hyemi Han, Youngkyoo KimAbstract:Here we demonstrate deep red light-sensing all-polymer Phototransistors with bulk heterojunction layers of poly[4,8-bis[(2-ethylhexyl)-oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) and poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)] (P(NDI2OD-T2)). The device performances were investigated by varying the incident light intensity of the deep red light (675 nm), while the signal amplification capability was examined by changing the gate and drain voltages. The result showed that the present all-polymer Phototransistors exhibited higher photoresponsivity (∼14 A/W) and better on/off photoswitching characteristics than the devices with the pristine polymers under illumination with the deep red light. The enhanced Phototransistor performances were attributed to the well-aligned nanofiber-like morphology and nanocrystalline P(NDI2OD-T2) domains in the blend films, which are beneficia...
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Efficient Deep Red Light-Sensing All-Polymer Phototransistors with p‑type/n-type Conjugated Polymer Bulk Heterojunction Layers
2017Co-Authors: Sungho Nam, Hwajeong Kim, Jooyeok Seo, Hyemi Han, Donal D. C. Bradley, Youngkyoo KimAbstract:Here we demonstrate deep red light-sensing all-polymer Phototransistors with bulk heterojunction layers of poly[4,8-bis[(2-ethylhexyl)-oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) and poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)] (P(NDI2OD-T2)). The device performances were investigated by varying the incident light intensity of the deep red light (675 nm), while the signal amplification capability was examined by changing the gate and drain voltages. The result showed that the present all-polymer Phototransistors exhibited higher photoresponsivity (∼14 A/W) and better on/off photoswitching characteristics than the devices with the pristine polymers under illumination with the deep red light. The enhanced Phototransistor performances were attributed to the well-aligned nanofiber-like morphology and nanocrystalline P(NDI2OD-T2) domains in the blend films, which are beneficial for charge separation and charge transport in the in-plane direction
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all polymer Phototransistors with bulk heterojunction sensing layers of thiophene based electron donating and thienopyrroledione based electron accepting polymers
Organic Electronics, 2016Co-Authors: Sungho Nam, Hwajeong Kim, D D C Bradley, Youngkyoo KimAbstract:Abstract All-polymer Phototransistors consisting of bulk heterojunction (BHJ) nanolayers of electron-donating (p-type) and electron-accepting (n-type) polymers are attractive candidates for applications such as light-sensing and light-switching devices. Here, we report efficient green-light-sensing all-polymer Phototransistors based on BHJ layers of poly(3-hexylthiophene) (P3HT) and poly[(4,8-bis(2-ethylhexyloxy)-benzo[1,2- b :4,5- b ]-dithiophene)-2,6-diyl- alt -( N -2-ethylhexylthieno[3,4- c ]pyrrole-4,6-dione)-2,6-diyl]] (PBDTTPD) polymers. To understand the Phototransistor characteristics, all devices were exposed to a green monochromatic light (555 nm) with different incident power intensities. The results showed that the P3HT:PBDTTPD (80:20) layer are more advantageous than the pristine P3HT layers in terms of efficient charge separation and transport. The responsivity value of devices with the P3HT:PBDTTPD (80:20) layers reached 33.3 A/W, which is 25 and 28 times higher than those obtained with pristine the pristine P3HT or P3HT:PBDTTPD (60:40) layers. The enhanced device performance of the P3HT:PBDTTPD (80:20) Phototransistors is attributable to an efficient charge separation, prevalent edge-on chain orientation, and relatively smoother surface morphology, which might facilitate improved charge transport in the lateral direction.
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organic Phototransistors with nanoscale phase separated polymer polymer bulk heterojunction layers
Nanoscale, 2011Co-Authors: Hyemin Hwang, Sungho Nam, Hwajeong Kim, D D C Bradley, Youngkyoo KimAbstract:Low-cost detectors for sensing photons at a low light intensity are of crucial importance in modern science. Phototransistors can deliver better signals of low-intensity light by electrical amplification, but conventional inorganic Phototransistors have a limitation owing to their high temperature processes in vacuum. In this work, we demonstrate organic Phototransistors with polymer/polymer bulk heterojunction blend films (mixtures of p-type and n-type semiconducting polymers), which can be fabricated by inexpensive solution processes at room temperature. The key idea here is to effectively exploit hole charges (from p-type polymer) as major signaling carriers by employing p-type transistor geometry, while the n-type polymer helps efficient charge separation from excitons generated by incoming photons. Results showed that the present organic transistors exhibited proper functions as p-type Phototransistors with ∼4.3 A W−1 responsivity at a low light intensity (1 µW cm−2), which supports their encouraging potential to replace conventional cooled charge coupled devices (CCD) for low-intensity light detection applications.
Feng Yan - One of the best experts on this subject based on the ideXlab platform.
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perovskite poly 3 hexylthiophene graphene multiheterojunction Phototransistors with ultrahigh gain in broadband wavelength region
ACS Applied Materials & Interfaces, 2017Co-Authors: Chao Xie, Feng YanAbstract:Organometal halide perovskite materials have attracted much attention recently for their excellent optoelectronic properties. Here, we report an ultrasensitive Phototransistor based on the multiheterojunction of CH3NH3PbI3–xClx perovskite/poly(3-hexylthiophene)/graphene for the first time. Since the photoexcited electrons and holes are effectively separated by the poly(3-hexylthiophene) layer, high-density electrons are trapped in the perovskite layer, leading to a strong photogating effect on the underlying graphene channel. The Phototransistor demonstrates an unprecedented ultrahigh responsivity of ∼4.3 × 109 A/W and a gain approaching 1010 electrons per photon, respectively. More importantly, the device is sensitive in a broadband wavelength region from ultraviolet to near-infrared, which has not yet been achieved with other perovskite photodetectors. It is expected that the novel perovskite Phototransistor will find promising applications as photodetection and imaging devices in the future.
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Perovskite/Poly(3-hexylthiophene)/Graphene Multiheterojunction Phototransistors with Ultrahigh Gain in Broadband Wavelength Region
2017Co-Authors: Chao Xie, Feng YanAbstract:Organometal halide perovskite materials have attracted much attention recently for their excellent optoelectronic properties. Here, we report an ultrasensitive Phototransistor based on the multiheterojunction of CH3NH3PbI3–xClx perovskite/poly(3-hexylthiophene)/graphene for the first time. Since the photoexcited electrons and holes are effectively separated by the poly(3-hexylthiophene) layer, high-density electrons are trapped in the perovskite layer, leading to a strong photogating effect on the underlying graphene channel. The Phototransistor demonstrates an unprecedented ultrahigh responsivity of ∼4.3 × 109 A/W and a gain approaching 1010 electrons per photon, respectively. More importantly, the device is sensitive in a broadband wavelength region from ultraviolet to near-infrared, which has not yet been achieved with other perovskite photodetectors. It is expected that the novel perovskite Phototransistor will find promising applications as photodetection and imaging devices in the future
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highly sensitive organic near infrared Phototransistors based on poly 3 hexylthiophene and pbs quantum dots
Journal of Materials Chemistry, 2012Co-Authors: Zhenhua Sun, Feng YanAbstract:Highly sensitive near-infrared (NIR) Phototransistors based on poly(3-hexylthiophene) (P3HT) and lead sulfide quantum dots (PbS QDs) were fabricated by a solution process. The Phototransistors show high responsivity up to 2 × 104 A W−1 under NIR illumination with wavelength of 895 nm, which is much bigger than that of the photodetectors based on PbS QDs or organic semiconductors only. The sensing mechanism is attributed to the photo-induced electrons generated in the PbS QDs, which increase the threshold voltage of the transistor. These Phototransistors may find promising applications as infrared sensors for their high responsivity, easy fabrication, low cost and flexibility.
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Thin film field-effect Phototransistors from bandgap-tunable, solution-processed, few-layer reduced graphene oxide films
Advanced Materials, 2010Co-Authors: Haixin Chang, Xiao Ming Tao, Qinghong Yuan, Feng Yan, Zhenhua Sun, Zijian ZhengAbstract:Thin film field-effect Phototransistors (FETs) can be developed from bandgap-tunable, solution-processed, few-layer reduced graphene oxide (FRGO) films. Large-area FRGO films with tunable bandgaps ranging from 2.2 eV to 0.5 eV can be achieved readily by solution-processing technique such as spin-coating. The electronic and optoelectronic properties of FRGO FETs are found to be closely related to their bandgap energy. The resulting Phototransistor has great application potential in the field of photodetection.
Gerasimos Konstantatos - One of the best experts on this subject based on the ideXlab platform.
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ultrasensitive all 2d mos 2 Phototransistors enabled by an out of plane mos 2 pn homojunction
Nature Communications, 2017Co-Authors: Nengjie Huo, Gerasimos KonstantatosAbstract:Two-dimensional transition metal dichalcogenide-based photodetectors have demonstrated potential for the next generation of 2-dimensional optoelectronics. However, to date, their sensitivity has not been superior to that of other technologies. Here we report an ultrasensitive two-dimensional photodetector employing an in-plane Phototransistor with an out-of-plane vertical MoS2 p–n junction as a sensitizing scheme. The vertical built-in field is introduced for the first time in the transport channel of MoS2 Phototransistors by facile chemical surface doping, which separates the photo-excited carriers efficiently and produces a photoconductive gain of >105 electrons per photon, external quantum efficiency greater than 10%, responsivity of 7 × 104 A W−1, and a time response on the order of tens of ms. This taken together with a very low noise power density yields a record sensitivity with specific detectivity $$D^*$$ of 3.5 × 1014 Jones in the visible and a broadband response up to 1000 nm. Photodetectors based on 2D transition metal dichalcogenides exhibit ever increasingly competitive performance, yet not superior to that of alternative technologies. Here, the authors devise a MoS2-based Phototransistor with an out-of-plane junction, yielding a record detectivity combined with broadband response.
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Integrating an electrically active colloidal quantum dot photodiode with a graphene Phototransistor
Nature Communications, 2016Co-Authors: Ivan Nikitskiy, Stijn Goossens, Dominik Kufer, Tania Lasanta, Gabriele Navickaite, Frank H. L. Koppens, Gerasimos KonstantatosAbstract:The combination of fast photo-response and high gain plays a pivotal role in photodetector devices. Here the authors combine a colloidal quantum dot photodiode with a graphene Phototransistor to overcome the speed, quantum efficiency and linear dynamic range limitations of available Phototransistors. The realization of low-cost photodetectors with high sensitivity, high quantum efficiency, high gain and fast photoresponse in the visible and short-wave infrared remains one of the challenges in optoelectronics. Two classes of photodetectors that have been developed are photodiodes and Phototransistors, each of them with specific drawbacks. Here we merge both types into a hybrid photodetector device by integrating a colloidal quantum dot photodiode atop a graphene Phototransistor. Our hybrid detector overcomes the limitations of a Phototransistor in terms of speed, quantum efficiency and linear dynamic range. We report quantum efficiencies in excess of 70%, gain of 10^5 and linear dynamic range of 110 dB and 3 dB bandwidth of 1.5 kHz. This constitutes a demonstration of an optoelectronically active device integrated directly atop graphene and paves the way towards a generation of flexible highly performing hybrid two-dimensional (2D)/0D optoelectronics.
Jun Gou - One of the best experts on this subject based on the ideXlab platform.
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light modulated vertical heterojunction Phototransistors with distinct logical photocurrents
Light-Science & Applications, 2020Co-Authors: Jiayue Han, Fang Wang, Xiaoqing Chen, Xinran Wang, Ming Yang, Qi Han, Fang Zhong, He Zhu, Chongxin Shan, Jun GouAbstract:The intriguing carrier dynamics in graphene heterojunctions have stimulated great interest in modulating the optoelectronic features to realize high-performance photodetectors. However, for most Phototransistors, the photoresponse characteristics are modulated with an electrical gate or a static field. In this paper, we demonstrate a graphene/C60/pentacene vertical Phototransistor to tune both the photoresponse time and photocurrent based on light modulation. By exploiting the power-dependent multiple states of the photocurrent, remarkable logical photocurrent switching under infrared light modulation occurs in a thick C60 layer (11 nm) device, which implies competition of the photogenerated carriers between graphene/C60 and C60/pentacene. Meanwhile, we observe a complete positive-negative alternating process under continuous 405 nm irradiation. Furthermore, infrared light modulation of a thin C60 (5 nm) device results in a photoresponsivity improvement from 3425 A/W up to 7673 A/W, and we clearly probe the primary reason for the distinct modulation results between the 5 and 11 nm C60 devices. In addition, the tuneable bandwidth of the infrared response from 10 to 3 × 103 Hz under visible light modulation is explored. Such distinct types of optical modulation phenomena and logical photocurrent inversion characteristics pave the way for future tuneable logical photocurrent switching devices and high-performance Phototransistors with vertical graphene heterojunction structures. Two forms of carbon and a hydrocarbon are combined in a Phototransistor, which creates changes in optical and electronic behavior in response to different wavelengths of light, with properties that will be useful for both research and commercial applications. The innovative Phototransistor has been developed by Jiayue Han and colleagues at the University of Electronic Science and Technology of China, in Chengdu, with co-workers at other Chinese research centers. It has a layer composed of spherical C60 molecules, sandwiched between the form of carbon known as graphene and the hydrocarbon pentacene. Gold and silicon-based electrodes complete the structure. The optoelectronic properties created at the junctions between the different layers overcome limitations of simpler graphene based devices. The modulation of optical and electronic behavior achieved by the system could be used in new logical switching devices.
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light modulated vertical heterojunction Phototransistors with distinct logical photocurrents
Light-Science & Applications, 2020Co-Authors: Jiayue Han, Xiaoqing Chen, Xinran Wang, Ming Yang, Qi Han, Fang Zhong, He Zhu, Chongxin Shan, Jun GouAbstract:The intriguing carrier dynamics in graphene heterojunctions have stimulated great interest in modulating the optoelectronic features to realize high-performance photodetectors. However, for most Phototransistors, the photoresponse characteristics are modulated with an electrical gate or a static field. In this paper, we demonstrate a graphene/C60/pentacene vertical Phototransistor to tune both the photoresponse time and photocurrent based on light modulation. By exploiting the power-dependent multiple states of the photocurrent, remarkable logical photocurrent switching under infrared light modulation occurs in a thick C60 layer (11 nm) device, which implies competition of the photogenerated carriers between graphene/C60 and C60/pentacene. Meanwhile, we observe a complete positive-negative alternating process under continuous 405 nm irradiation. Furthermore, infrared light modulation of a thin C60 (5 nm) device results in a photoresponsivity improvement from 3425 A/W up to 7673 A/W, and we clearly probe the primary reason for the distinct modulation results between the 5 and 11 nm C60 devices. In addition, the tuneable bandwidth of the infrared response from 10 to 3 × 103 Hz under visible light modulation is explored. Such distinct types of optical modulation phenomena and logical photocurrent inversion characteristics pave the way for future tuneable logical photocurrent switching devices and high-performance Phototransistors with vertical graphene heterojunction structures.