sunbin hwang | Kyushu University (original) (raw)
Papers by sunbin hwang
Nature Communications
Electronic fibres have been considered one of the desired device platforms due to their dimension... more Electronic fibres have been considered one of the desired device platforms due to their dimensional compatibility with fabrics by weaving with yarns. However, a precise connecting process between each electronic fibre is essential to configure the desired electronic circuits or systems. Here, we present an integrated electronic fibre platform by fabricating electronic devices onto a one-dimensional microfibre substrate. Electronic components such as transistors, inverters, ring oscillators, and thermocouples are integrated together onto the outer surface of a fibre substrate with precise semiconductor and electrode patterns. Our results show that electronic components can be integrated on a single fibre with reliable operation. We evaluate the electronic properties of the chip on the fibre as a multifunctional electronic textile platform by testing their switching and data processing, as well as sensing or transducing units for detecting optical/thermal signals. The demonstration of...
Additional file 1: Figure S1. (a) Optical microscopic image of our OFET and MIS capacitor with a ... more Additional file 1: Figure S1. (a) Optical microscopic image of our OFET and MIS capacitor with a hybrid dielectric. (b) Gate leakage currents as a function of the gate voltage (IGS-VGS) of the OFETs that include hybrid gate dielectrics with various PA-SAMs. Figure S2. Output characteristics as a function of the gate voltage (IDS-VGS) of the OFETs with hybrid dielectrics with various PA-SAMs (a) reference Al2O3 (b) HPA, (c) DDPA (d) ODPA, (e) PHDA, (f) MDPA, (g) PFPA and (h) HUPA.
The Japan Society of Applied Physics, 2017
Influence of contact resistance for organic-inorganic perovskite transistors 九大 OPERA,九大 I2CNER, ... more Influence of contact resistance for organic-inorganic perovskite transistors 九大 OPERA,九大 I2CNER, JST/ERATO, ISIT, 松島敏則 *,S. Hwang , 寺川しのぶ , 藤原隆 , A. S. D. Sandanayaka, C. Qin, and C. Adachi* OPERA, Kyushu Univ. , I2CNER, Kyushu Univ. , JST/ERATO, ISIT, T. Matsushima*, S. Hwang, S. Terakawa, T. Fujihara, A. S. D. Sandanayaka, C. Qin, and C. Adachi* E-mail: tmatusim@opera.kyushu-u.ac.jp, adachi@cstf.kyushu-u.ac.jp
Electronic textiles have been considered one of the desired device platforms due to their dimensi... more Electronic textiles have been considered one of the desired device platforms due to their dimensional compatibility with fabrics by weaving them with yarn. However, the existing electronic textile platforms are generally composed of only one type of electronic component with a single function on a fiber substrate because of processing challenges. A precise connecting process between each electronic fiber is essential to configure the desired electronic circuits or systems. Here we present a chip on a fiber, a new electronic fiber platform, by introducing large scale integration of electronic device or circuit components onto a one-dimensional microfiber substrate. The electronic components such as transistors, inverters, ring oscillators, and thermocouples were integrated together onto the outer surface of a fiber substrate with precise semiconductor and electrode patterns. Our results show that the electronic components can be integrated on a single fiber with reliable operation. W...
The Japan Society of Applied Physics, 2016
Construction and Building Materials, 2021
Abstract Herein, we introduce p-type thermoelectric materials composed of Portland cement (PC) an... more Abstract Herein, we introduce p-type thermoelectric materials composed of Portland cement (PC) and slag-based alkali-activated cement (AAC) composites containing multi-walled carbon nanotube (MWCNT). Numerous characteristics related to the thermoelectric properties, in this case the electrical conductivity, compressive strength, thermal conductivity, Seebeck coefficient, and power factor of composites composed of two types of binders, were investigated, and various physicochemical properties were analyzed to determine their enhancement mechanisms. Based on the initial test results, MWCNT-embedded AAC composites were found to be feasible as a thermoelectric material, and an AAC thermoelectric module containing 2.0 wt% MWCNT was therefore additionally fabricated. The AAC-based thermoelectric module was tested with regard to its energy-harvesting performance, with the result confirming that the module was capable of generating electrical power.
Advanced Electronic Materials, 2020
Organic light-emitting diodes (LEDs)are famous commercialized organic devices used as display mod... more Organic light-emitting diodes (LEDs)are famous commercialized organic devices used as display modules in smartphones. However, other electronic components have not been completely replaced by organic materials yet because of the poor performance and lifetime of these materials. Several research groups have therefore focused their efforts on developing various electronic elements from organic materials such as electrodes, capacitors, inductors, memory, photovoltaic cells, sensors, transistors, and non-volatile memory for complex electronic devices. [15-17] Nevertheless, only a few organic electronic filters for circuits with noisy electric signals have been reported. A Schmitt trigger, one of the most commonly used versatile noise filters, consists of a comparator circuit with hysteresis that is induced by applying positive feedback to the non-inverting input of a comparator or differential amplifier. These characteristics of a Schmitt trigger allow the output signal to retain its signal until the input signal changes enough to change the trigger, hence use of the term "trigger." [18] One of representative use of a Schmitt trigger is as an electric noise filter in integrated circuits. It is particularly effective in signaling conditioning applications such as increasing immunity to noise in circuits caused by contact bounce in switches or fluctuations from unpredictable output changes. Another use of a Schmitt trigger is an onebit analog-to-digital converter, which transform an analog input to a digital output signals using a low-to-high signal transition Although there have been many attempts to replace conventional inorganic electronics with organic materials that can be mass produced at low cost, few organic electronic filters to increase immunity to electrical noise have been reported thus far. Conventional Schmitt triggers or their inverters are used in many electronic circuits as versatile electronic noise filters. However, it is challenging to manufacture organic electronic systems with complex circuitry. In this study, a simple, all-solid-state organic Schmitt trigger consisting of twin two-in-one organic ferroelectric memory transistors with the same chemical compositions and device dimensions but different threshold voltages is introduced. Threshold voltages and hysteresis in the two-in-one devices can be controlled by polarization switching as demonstrated in a previous study. Hysteresis of a ferroelectric p-type depletion load inverter can be achieved using twin two-in-one devices when the sweep voltage is higher than the critical gate voltages. This facilitates inverter characteristics at two different threshold voltages, and realizing a Schmitt trigger. Finally, based on simulation program with integrated circuit emphasis (SPICE) simulation, guidelines are proposed on how to design organic Schmitt triggers with p-or n-type materials and ferroelectric or charge-trapping mechanisms to achieve inverting or non-inverting characteristics.
ACS Energy Letters, 2020
While perovskite solar cells (PSCs) have emerged as promising low-cost solar power generators, mo... more While perovskite solar cells (PSCs) have emerged as promising low-cost solar power generators, most reported high-performance PSCs employ electron transport layers (ETLs, mainly TiO2) treated at hi...
Journal of Materials Chemistry A, 2020
A large-scale (64 cm2), spray-coated nickel oxide (NiO) film as a hole-transport layer has succes... more A large-scale (64 cm2), spray-coated nickel oxide (NiO) film as a hole-transport layer has successfully yielded >17% efficiency in planar triple-cation perovskite solar cells (PSCs).
Polymer, 2019
Shape, size, and orientation of fillers within polymer matrix are important factors for realizing... more Shape, size, and orientation of fillers within polymer matrix are important factors for realizing various composite functionalities. Here, we describe an industrially scalable approach to preparing composites bearing highly aligned model hexagonal boron nitride filler (hBN) by simple melt-pressing. This outcome is achieved by using a malleable but thermal stiffening polymer matrix. The matrix maintains or even increases its stiffness during processing at elevated temperatures, producing the composites with highly aligned hBN and consequently a high thermal conductivity (28 W/mK). Furthermore, the composite bearing aligned hBN exhibits a 62% reduction in oxygen permeation with only 2.7 vol% of hBN. Since the matrix can be chemically depolymerized with an aid of acid, it is also possible to recover the hBN from the composite without physical/chemical denaturation of the filler, thus the recovered filler can be re-used in the future.
ACS Applied Materials & Interfaces, 2019
Organic electronics demand new platforms that can make integrated circuits and undergo mass produ... more Organic electronics demand new platforms that can make integrated circuits and undergo mass production while maintaining diverse functions with high performance. The fieldeffect transistor has great potential to be a multifunctional device capable of sensing, data processing, data storage and display. Currently, transistor-based devices cannot be considered intrinsic multifunctional devices because all installed functions are mutually coupled. Such incompatibilities are a crucial barrier to developing an all-in-one multifunctional device capable of driving each function individually. In this study, we focus on the decoupling of electric switching and data storage functions in an organic ferroelectric memory transistor. To overcome the incompatibility of each function, the high permittivity needed for electrical switching and the ferroelectricity needed for data storage become compatible by restricting the motion of poly(vinylidene fluoride-trifluoroethylene) via photocrosslinking with bis-perfluorobenzoazide. The two-in-one device consisting of a photocrosslinked ferroelectric layer exhibits reversible and individual dual-functional operation as a typical transistor with nonvolatile memory. Moreover, a p-MOS depletion load inverter composed of the two transistors with different threshold voltages is also demonstrated by simply changing only one of the threshold voltages by polarization switching. We believe the two-in-one device will be considered a potential component of integrated organic logic circuits, including memory, in the future.
ACS Applied Materials & Interfaces, 2019
Wearable technology offers new ways to be more proactive about our health and surroundings in rea... more Wearable technology offers new ways to be more proactive about our health and surroundings in real time. For next-generation wearable systems, robust storage or recording media are required to monitor and process the essential electrical signals generated under various unpredictable strain conditions. Here, we report the first fibriform organic transistor memory integrated on a thin and flexible metal wire. A capillary tube coating system allows the formation of a thin and nanograined organic ferroelectric film on the wire. The uniform morphology imparts excellent switching stability (~ 100 cycles), quasi-permanent retention (over 5 × 10 4 s) and low-voltage operation (below 5 V) to the fiber-shaped memory devices. When sewn in a stretchable textile fabric, the memory fiber achieves long retention time over 10 4 s with negligible degradation of memory window even under a constant diagonal strain of 100 % that exhibits reliable data storage under tough environments. These results illustrate the possibility of the practical, wearable fiber memory for recording electronic signals in smart garment applications.
ACS Energy Letters, 2018
Herein, we achieved, air-stable low-temperature processed PSC (L-PSC) using alkalimetal modified ... more Herein, we achieved, air-stable low-temperature processed PSC (L-PSC) using alkalimetal modified ZnO ETLs. Using a simple chemical alkali-metal modification method, the surface defects of the ZnO were effectively passivated. As a result, the interfacial decomposition reactions were suppressed, while raising the Fermi energy level and enhancing electron mobility. The improved interfacial charge transfer and internal electric field in the developed L-PSC using K modified ZnO (ZnO-K) exhibited an improved power conversion efficiency (PCE) of 19.91% with negligible hysteresis, while a pristine ZnO based L-PSC exhibited a PCE of 16.12% with significant hysteresis. The ZnO-K based L-PSC also exhibited remarkably higher long-term airstorage stability (91% retention after 800 h) than pristine ZnO based L-PSCs (36% retention after 800 h) due to the suppressed decomposition reactions. The PCE and air-stability of our L-PSC with the modified ZnO are among the highest reported for PSCs processed ≤ 150 °C .
Journal of Alloys and Compounds, 2019
A simple, cost-effective, and one-step procedure for fabrication of gold-nanoparticle-transition ... more A simple, cost-effective, and one-step procedure for fabrication of gold-nanoparticle-transition metal oxide (Au-TMO) thin films with tuned optical and structural properties is described. In this approach, a homogeneous mixed precursor solution was used to fabricate Au-MoO 3 and Au-WO 3 thin films via a spray pyrolysis technique. The in-situ grown Au nanoparticles in the host matrices exhibited a characteristic surface plasmon resonance absorption in the visible-NIR region with peak positions at l max z 600 nm, z550 nm, and z575 nm for Au-MoO 3 , Au-a-WO 3 (amorphous), and Au-h-WO 3 (hexagonal) films, respectively. The structural and morphological characterization measurements confirmed that the high purity in-situ grown Au nanoparticles were 10e100 nm in size, and individual particles were embedded into the host matrices. These films were applied as plasmon-induced photoelectric conversion devices with ITO/NiO x /Au-WO 3 /Ag structures as a prototype device. The device exhibited a short-circuit current of 0.1 mA with an open-circuit voltage of~1.4 V under one-sun illumination. Our one-step fabrication approach is highly promising for fabricating other Au-TMOs thin films with tuned optical properties on a large area and can be applied for various optoelectronic applications.
![Research paper thumbnail of {"__content__"=>"Hybrid dielectrics composed of AlO and phosphonic acid self-assembled monolayers for performance improvement in low voltage organic field effect transistors.", "sub"=>[{"__content__"=>"2"}, {"__content__"=>"3"}]}](https://attachments.academia-assets.com/94589112/thumbnails/1.jpg)
](Nano convergence, 2018
Low voltage operational organic transistors (< 4 V) based on pentacene were successfully fabri... more Low voltage operational organic transistors (< 4 V) based on pentacene were successfully fabricated with hybrid dielectric films composed of aluminum oxide using atomic layer deposition and various phosphonic acid-based self-assembled monolayers as the gate dielectrics. High capacitances up to 279 nF/cm, low leakage current densities of 10 A/cm at 6 V, and high breakdown fields up to 7.5 MV/cm were obtained. The transistors with the octadecylphosphonic acid hybrid dielectric exhibited an improved saturation mobility of 0.58 cm/Vs, a subthreshold slope of 151 mV/decade, a threshold voltage of - 1.84 V and an on-off current ratio of 10. The low surface energies of the self-assembled monolayers having non-polar terminal groups, such as methyl and pentafluorophenoxy, improved the carrier conduction of the transistors due to the pentacene growth with an edge-on orientation for low voltage operation. The pentafluorophenoxy end-group showed an accumulation of holes at the semiconductor-...
Advanced Materials, 2016
A very high hole mobility of 15 cm2 V-1 s-1 along with negligible hysteresis are demonstrated in ... more A very high hole mobility of 15 cm2 V-1 s-1 along with negligible hysteresis are demonstrated in transistors with an organic-inorganic perovskite semiconductor. This high mobility results from the well-developed perovskite crystallites, improved conversion to perovskite, reduced hole trap density, and improved hole injection by employing a top-contact/top-gate structure with surface treatment and MoOx hole-injection layers.
![Research paper thumbnail of Thermally activated delayed fluorescence of Bis(9,9-dimethyl-9,10-dihydroacridine) dibenzo[ b,d ]thiophene 5,5-dioxide derivatives for organic light-emitting diodes](https://attachments.academia-assets.com/94589109/thumbnails/1.jpg)
](Journal of Luminescence, 2017
Thermally activated delayed fluorescence of Bis(9,9-dimethyl-9,10dihydroacridine) dibenzo[b,d]thi... more Thermally activated delayed fluorescence of Bis(9,9-dimethyl-9,10dihydroacridine) dibenzo[b,d]thiophene 5,5-dioxide derivatives for organic light-emitting diodes
Nature Communications
Electronic fibres have been considered one of the desired device platforms due to their dimension... more Electronic fibres have been considered one of the desired device platforms due to their dimensional compatibility with fabrics by weaving with yarns. However, a precise connecting process between each electronic fibre is essential to configure the desired electronic circuits or systems. Here, we present an integrated electronic fibre platform by fabricating electronic devices onto a one-dimensional microfibre substrate. Electronic components such as transistors, inverters, ring oscillators, and thermocouples are integrated together onto the outer surface of a fibre substrate with precise semiconductor and electrode patterns. Our results show that electronic components can be integrated on a single fibre with reliable operation. We evaluate the electronic properties of the chip on the fibre as a multifunctional electronic textile platform by testing their switching and data processing, as well as sensing or transducing units for detecting optical/thermal signals. The demonstration of...
Additional file 1: Figure S1. (a) Optical microscopic image of our OFET and MIS capacitor with a ... more Additional file 1: Figure S1. (a) Optical microscopic image of our OFET and MIS capacitor with a hybrid dielectric. (b) Gate leakage currents as a function of the gate voltage (IGS-VGS) of the OFETs that include hybrid gate dielectrics with various PA-SAMs. Figure S2. Output characteristics as a function of the gate voltage (IDS-VGS) of the OFETs with hybrid dielectrics with various PA-SAMs (a) reference Al2O3 (b) HPA, (c) DDPA (d) ODPA, (e) PHDA, (f) MDPA, (g) PFPA and (h) HUPA.
The Japan Society of Applied Physics, 2017
Influence of contact resistance for organic-inorganic perovskite transistors 九大 OPERA,九大 I2CNER, ... more Influence of contact resistance for organic-inorganic perovskite transistors 九大 OPERA,九大 I2CNER, JST/ERATO, ISIT, 松島敏則 *,S. Hwang , 寺川しのぶ , 藤原隆 , A. S. D. Sandanayaka, C. Qin, and C. Adachi* OPERA, Kyushu Univ. , I2CNER, Kyushu Univ. , JST/ERATO, ISIT, T. Matsushima*, S. Hwang, S. Terakawa, T. Fujihara, A. S. D. Sandanayaka, C. Qin, and C. Adachi* E-mail: tmatusim@opera.kyushu-u.ac.jp, adachi@cstf.kyushu-u.ac.jp
Electronic textiles have been considered one of the desired device platforms due to their dimensi... more Electronic textiles have been considered one of the desired device platforms due to their dimensional compatibility with fabrics by weaving them with yarn. However, the existing electronic textile platforms are generally composed of only one type of electronic component with a single function on a fiber substrate because of processing challenges. A precise connecting process between each electronic fiber is essential to configure the desired electronic circuits or systems. Here we present a chip on a fiber, a new electronic fiber platform, by introducing large scale integration of electronic device or circuit components onto a one-dimensional microfiber substrate. The electronic components such as transistors, inverters, ring oscillators, and thermocouples were integrated together onto the outer surface of a fiber substrate with precise semiconductor and electrode patterns. Our results show that the electronic components can be integrated on a single fiber with reliable operation. W...
The Japan Society of Applied Physics, 2016
Construction and Building Materials, 2021
Abstract Herein, we introduce p-type thermoelectric materials composed of Portland cement (PC) an... more Abstract Herein, we introduce p-type thermoelectric materials composed of Portland cement (PC) and slag-based alkali-activated cement (AAC) composites containing multi-walled carbon nanotube (MWCNT). Numerous characteristics related to the thermoelectric properties, in this case the electrical conductivity, compressive strength, thermal conductivity, Seebeck coefficient, and power factor of composites composed of two types of binders, were investigated, and various physicochemical properties were analyzed to determine their enhancement mechanisms. Based on the initial test results, MWCNT-embedded AAC composites were found to be feasible as a thermoelectric material, and an AAC thermoelectric module containing 2.0 wt% MWCNT was therefore additionally fabricated. The AAC-based thermoelectric module was tested with regard to its energy-harvesting performance, with the result confirming that the module was capable of generating electrical power.
Advanced Electronic Materials, 2020
Organic light-emitting diodes (LEDs)are famous commercialized organic devices used as display mod... more Organic light-emitting diodes (LEDs)are famous commercialized organic devices used as display modules in smartphones. However, other electronic components have not been completely replaced by organic materials yet because of the poor performance and lifetime of these materials. Several research groups have therefore focused their efforts on developing various electronic elements from organic materials such as electrodes, capacitors, inductors, memory, photovoltaic cells, sensors, transistors, and non-volatile memory for complex electronic devices. [15-17] Nevertheless, only a few organic electronic filters for circuits with noisy electric signals have been reported. A Schmitt trigger, one of the most commonly used versatile noise filters, consists of a comparator circuit with hysteresis that is induced by applying positive feedback to the non-inverting input of a comparator or differential amplifier. These characteristics of a Schmitt trigger allow the output signal to retain its signal until the input signal changes enough to change the trigger, hence use of the term "trigger." [18] One of representative use of a Schmitt trigger is as an electric noise filter in integrated circuits. It is particularly effective in signaling conditioning applications such as increasing immunity to noise in circuits caused by contact bounce in switches or fluctuations from unpredictable output changes. Another use of a Schmitt trigger is an onebit analog-to-digital converter, which transform an analog input to a digital output signals using a low-to-high signal transition Although there have been many attempts to replace conventional inorganic electronics with organic materials that can be mass produced at low cost, few organic electronic filters to increase immunity to electrical noise have been reported thus far. Conventional Schmitt triggers or their inverters are used in many electronic circuits as versatile electronic noise filters. However, it is challenging to manufacture organic electronic systems with complex circuitry. In this study, a simple, all-solid-state organic Schmitt trigger consisting of twin two-in-one organic ferroelectric memory transistors with the same chemical compositions and device dimensions but different threshold voltages is introduced. Threshold voltages and hysteresis in the two-in-one devices can be controlled by polarization switching as demonstrated in a previous study. Hysteresis of a ferroelectric p-type depletion load inverter can be achieved using twin two-in-one devices when the sweep voltage is higher than the critical gate voltages. This facilitates inverter characteristics at two different threshold voltages, and realizing a Schmitt trigger. Finally, based on simulation program with integrated circuit emphasis (SPICE) simulation, guidelines are proposed on how to design organic Schmitt triggers with p-or n-type materials and ferroelectric or charge-trapping mechanisms to achieve inverting or non-inverting characteristics.
ACS Energy Letters, 2020
While perovskite solar cells (PSCs) have emerged as promising low-cost solar power generators, mo... more While perovskite solar cells (PSCs) have emerged as promising low-cost solar power generators, most reported high-performance PSCs employ electron transport layers (ETLs, mainly TiO2) treated at hi...
Journal of Materials Chemistry A, 2020
A large-scale (64 cm2), spray-coated nickel oxide (NiO) film as a hole-transport layer has succes... more A large-scale (64 cm2), spray-coated nickel oxide (NiO) film as a hole-transport layer has successfully yielded >17% efficiency in planar triple-cation perovskite solar cells (PSCs).
Polymer, 2019
Shape, size, and orientation of fillers within polymer matrix are important factors for realizing... more Shape, size, and orientation of fillers within polymer matrix are important factors for realizing various composite functionalities. Here, we describe an industrially scalable approach to preparing composites bearing highly aligned model hexagonal boron nitride filler (hBN) by simple melt-pressing. This outcome is achieved by using a malleable but thermal stiffening polymer matrix. The matrix maintains or even increases its stiffness during processing at elevated temperatures, producing the composites with highly aligned hBN and consequently a high thermal conductivity (28 W/mK). Furthermore, the composite bearing aligned hBN exhibits a 62% reduction in oxygen permeation with only 2.7 vol% of hBN. Since the matrix can be chemically depolymerized with an aid of acid, it is also possible to recover the hBN from the composite without physical/chemical denaturation of the filler, thus the recovered filler can be re-used in the future.
ACS Applied Materials & Interfaces, 2019
Organic electronics demand new platforms that can make integrated circuits and undergo mass produ... more Organic electronics demand new platforms that can make integrated circuits and undergo mass production while maintaining diverse functions with high performance. The fieldeffect transistor has great potential to be a multifunctional device capable of sensing, data processing, data storage and display. Currently, transistor-based devices cannot be considered intrinsic multifunctional devices because all installed functions are mutually coupled. Such incompatibilities are a crucial barrier to developing an all-in-one multifunctional device capable of driving each function individually. In this study, we focus on the decoupling of electric switching and data storage functions in an organic ferroelectric memory transistor. To overcome the incompatibility of each function, the high permittivity needed for electrical switching and the ferroelectricity needed for data storage become compatible by restricting the motion of poly(vinylidene fluoride-trifluoroethylene) via photocrosslinking with bis-perfluorobenzoazide. The two-in-one device consisting of a photocrosslinked ferroelectric layer exhibits reversible and individual dual-functional operation as a typical transistor with nonvolatile memory. Moreover, a p-MOS depletion load inverter composed of the two transistors with different threshold voltages is also demonstrated by simply changing only one of the threshold voltages by polarization switching. We believe the two-in-one device will be considered a potential component of integrated organic logic circuits, including memory, in the future.
ACS Applied Materials & Interfaces, 2019
Wearable technology offers new ways to be more proactive about our health and surroundings in rea... more Wearable technology offers new ways to be more proactive about our health and surroundings in real time. For next-generation wearable systems, robust storage or recording media are required to monitor and process the essential electrical signals generated under various unpredictable strain conditions. Here, we report the first fibriform organic transistor memory integrated on a thin and flexible metal wire. A capillary tube coating system allows the formation of a thin and nanograined organic ferroelectric film on the wire. The uniform morphology imparts excellent switching stability (~ 100 cycles), quasi-permanent retention (over 5 × 10 4 s) and low-voltage operation (below 5 V) to the fiber-shaped memory devices. When sewn in a stretchable textile fabric, the memory fiber achieves long retention time over 10 4 s with negligible degradation of memory window even under a constant diagonal strain of 100 % that exhibits reliable data storage under tough environments. These results illustrate the possibility of the practical, wearable fiber memory for recording electronic signals in smart garment applications.
ACS Energy Letters, 2018
Herein, we achieved, air-stable low-temperature processed PSC (L-PSC) using alkalimetal modified ... more Herein, we achieved, air-stable low-temperature processed PSC (L-PSC) using alkalimetal modified ZnO ETLs. Using a simple chemical alkali-metal modification method, the surface defects of the ZnO were effectively passivated. As a result, the interfacial decomposition reactions were suppressed, while raising the Fermi energy level and enhancing electron mobility. The improved interfacial charge transfer and internal electric field in the developed L-PSC using K modified ZnO (ZnO-K) exhibited an improved power conversion efficiency (PCE) of 19.91% with negligible hysteresis, while a pristine ZnO based L-PSC exhibited a PCE of 16.12% with significant hysteresis. The ZnO-K based L-PSC also exhibited remarkably higher long-term airstorage stability (91% retention after 800 h) than pristine ZnO based L-PSCs (36% retention after 800 h) due to the suppressed decomposition reactions. The PCE and air-stability of our L-PSC with the modified ZnO are among the highest reported for PSCs processed ≤ 150 °C .
Journal of Alloys and Compounds, 2019
A simple, cost-effective, and one-step procedure for fabrication of gold-nanoparticle-transition ... more A simple, cost-effective, and one-step procedure for fabrication of gold-nanoparticle-transition metal oxide (Au-TMO) thin films with tuned optical and structural properties is described. In this approach, a homogeneous mixed precursor solution was used to fabricate Au-MoO 3 and Au-WO 3 thin films via a spray pyrolysis technique. The in-situ grown Au nanoparticles in the host matrices exhibited a characteristic surface plasmon resonance absorption in the visible-NIR region with peak positions at l max z 600 nm, z550 nm, and z575 nm for Au-MoO 3 , Au-a-WO 3 (amorphous), and Au-h-WO 3 (hexagonal) films, respectively. The structural and morphological characterization measurements confirmed that the high purity in-situ grown Au nanoparticles were 10e100 nm in size, and individual particles were embedded into the host matrices. These films were applied as plasmon-induced photoelectric conversion devices with ITO/NiO x /Au-WO 3 /Ag structures as a prototype device. The device exhibited a short-circuit current of 0.1 mA with an open-circuit voltage of~1.4 V under one-sun illumination. Our one-step fabrication approach is highly promising for fabricating other Au-TMOs thin films with tuned optical properties on a large area and can be applied for various optoelectronic applications.
Nano convergence, 2018
Low voltage operational organic transistors (< 4 V) based on pentacene were successfully fabri... more Low voltage operational organic transistors (< 4 V) based on pentacene were successfully fabricated with hybrid dielectric films composed of aluminum oxide using atomic layer deposition and various phosphonic acid-based self-assembled monolayers as the gate dielectrics. High capacitances up to 279 nF/cm, low leakage current densities of 10 A/cm at 6 V, and high breakdown fields up to 7.5 MV/cm were obtained. The transistors with the octadecylphosphonic acid hybrid dielectric exhibited an improved saturation mobility of 0.58 cm/Vs, a subthreshold slope of 151 mV/decade, a threshold voltage of - 1.84 V and an on-off current ratio of 10. The low surface energies of the self-assembled monolayers having non-polar terminal groups, such as methyl and pentafluorophenoxy, improved the carrier conduction of the transistors due to the pentacene growth with an edge-on orientation for low voltage operation. The pentafluorophenoxy end-group showed an accumulation of holes at the semiconductor-...
Advanced Materials, 2016
A very high hole mobility of 15 cm2 V-1 s-1 along with negligible hysteresis are demonstrated in ... more A very high hole mobility of 15 cm2 V-1 s-1 along with negligible hysteresis are demonstrated in transistors with an organic-inorganic perovskite semiconductor. This high mobility results from the well-developed perovskite crystallites, improved conversion to perovskite, reduced hole trap density, and improved hole injection by employing a top-contact/top-gate structure with surface treatment and MoOx hole-injection layers.
Journal of Luminescence, 2017
Thermally activated delayed fluorescence of Bis(9,9-dimethyl-9,10dihydroacridine) dibenzo[b,d]thi... more Thermally activated delayed fluorescence of Bis(9,9-dimethyl-9,10dihydroacridine) dibenzo[b,d]thiophene 5,5-dioxide derivatives for organic light-emitting diodes