High-performance blue organic light-emitting diodes （OLEDs） are developed. A concept of using multiple-emissive layer （EML） configuration is adopted. In this letter, bis（2-methyl-8-quinolinolate）-4- （phenylphen...High-performance blue organic light-emitting diodes （OLEDs） are developed. A concept of using multiple-emissive layer （EML） configuration is adopted. In this letter, bis（2-methyl-8-quinolinolate）-4- （phenylphenolato）A1 （BAlq） and 9,10-di（naphtha-2-yl）anthracene （ADN）, which serve n- and p-type EMLs, respectively, are used to evaluate and demonstrate the multi-EML concept for blue OLEDs. The thickness effect of individual EMLs and the number of EMLs, e.g., triple and quadruple EML components, on the power efficiency of blue OLEDs are systematically investigated. To illustrate the point, the total thickness of the emissive region in different blue OLEDs are kept contact at 30 nm for comparison. The power efficiency of blue OLEDs with a quadruple EML structure of BAlq/ADN/BAlq/ADN is about 40% higher than that of blue OLEDs having a single EML unit. The Commission Internationale deL＇eclairage color coordinates of multi-EML OLEDs have values that represent the average of blue emissions from individual EMLs of BAlq and ADN.展开更多
CONSPECTUS:Single-atomic catalyst(SAC)incorporated in graphene plays an increasingly significant role in many applications,including sustainable energy conversion/storage and environmental systems.Such a synergistic s...CONSPECTUS:Single-atomic catalyst(SAC)incorporated in graphene plays an increasingly significant role in many applications,including sustainable energy conversion/storage and environmental systems.Such a synergistic structure commonly consisting of atomic metal active sites stabilized on a robust graphene support,is breaking through the intrinsic limitations of precious-metalbased catalysts and broadening a spectrum of applications,while attaining high atom utilization,remarkable novel catalytic activity,and conformational flexibility.Motivated from the unprecedented attractive features of SAC in graphene,enormous research efforts have been devoted to the development of this ultimate catalytic system.For the further advance and eventual success in this field,a general rule for the rational design of SAC is the first prerequisite.Unfortunately,the research effort for the exploration of the fundamental reaction mechanism and rational design principle has been frequently overlooked in spite of the significantly accumulated research efforts thus far.In this Account,we highlight a new perspective for the rational design of SAC in graphene,conceptually centered on the atomistic level heteroelement dopants of graphene.To provide the intuitive viewpoint on the SAC from the scientific perspective,we suggest a new classification scheme for versatile SACs reported thus far into“dopant catalyst”and“dopant-assisted catalyst”,based on the detailed role of dopant in the catalyst system.Thereafter,we highlight the crucial influencing factors on the catalytic activity of the dopant-induced-catalyst system and toward rational designing rule for high performance catalysts.The recent progress in the dopantinduced-catalyst system for a wide spectrum of catalytic applications,including oxygen reduction,oxygen evolution,hydrogen evolution,and CO_(2)reduction is summarized.Finally,we briefly discuss the challenges and opportunities for the future research direction.The exciting expectation for the well-defined,specifically tailored,high performance dopant-induced-catalyst system is anticipated to address global challenges,including climate change,energy crisis and worldwide pandemics.展开更多
Numerous studies have aimed to improve the mechanical flexibility of thin-film encapsulation,a key obstacle in commercializing wearable organic light-emitting diodes(OLEDs).This study develops a silbione-blended organ...Numerous studies have aimed to improve the mechanical flexibility of thin-film encapsulation,a key obstacle in commercializing wearable organic light-emitting diodes(OLEDs).This study develops a silbione-blended organic/inorganic hybrid epoxy polymer(hybrimer)with high toughness as an organic barrier to enhance the flexibility of organic-inorganic multi-barriers.The optimal silbioneblended hybrimer(SBH)films exhibit superior mechanical properties,including increased elongation and tensile strength,compared to the hybrimer.The 3.5-dyad SBH-based encapsulation achieves a water vapor transmission rate of 7.83×10^(-6)g/m^(2)/day and 9.45×10^(-5)g/m^(2)/day before and after bending at a strain of 2%,respectively.In addition,the SBH barrier effectively protects the inorganic barrier by forming a robust aluminate phase at the interface between the inorganic and organic barrier,even under harsh conditions of 85℃/85%relative humidity,demonstrating its potential for wearable applications.As a result,SBH-based encapsulations offer mechanical and environmental stability,making them ideal for wearable OLEDs.展开更多
Stretchable organic light-emitting diodes(OLEDs)are emerging as a key technology for next-generation wearable devices due to their uniform light emission,stable performance under stretching conditions,and various flex...Stretchable organic light-emitting diodes(OLEDs)are emerging as a key technology for next-generation wearable devices due to their uniform light emission,stable performance under stretching conditions,and various flexible substrates.This paper introduces stretchable OLEDs fabricated with laser-cut kirigami patterns and a multifunctional encapsulation multilayer(MEM)barrier.These OLEDs were subsequently transferred onto textiles.These stretchable OLEDs achieved a remarkable stretchability of up to 150%through optimized kirigami pattern and maintained 100%stretchability when integrated with textiles,preserving the flexibility of a textile substrate.Additionally,the MEM barrier provided ultraviolet(UV)reflection and waterproof properties,ensuring reliable performance in harsh environments.Stretchable OLEDs and stretchable fabric OLEDs demonstrated a high luminance of 18,983 cd/m^(2) and 10,205 cd/m^(2),with minimal emission variation under stretched conditions.Furthermore,the potential of stretchable fabric OLEDs for wearable healthcare applications was evaluated by measuring photoplethysmography(PPG)signals.Stable PPG signals were successfully obtained at a 20%stretched state.Adjusting light source intensity effectively compensated for signal quality degradation caused by stretching.These findings highlight the significant potential of stretchable fabric OLEDs for wearable devices and photodiagnostic platforms,offering broad applicability across diverse fields.展开更多
Driven by innovations in the form factor of organic light-emitting diode(OLED)displays,the application scope of OLED technology now encompasses the biomedical field,in addition to its existing application domains of m...Driven by innovations in the form factor of organic light-emitting diode(OLED)displays,the application scope of OLED technology now encompasses the biomedical field,in addition to its existing application domains of mobile phones,televisions,and lighting.This paper introduces an ultrathin,ultraflexible,and high-power bio-OLED patch with perfect waterproofing and an elongation of 2.04%through material and structural design.Furthermore,the OLED patch with a parallel-stacked OLED delivers a high output of 100 mW/cm^(2),achieves a 40%power density improvement compared to glass-based OLEDs using optimized encapsulation,and is suitable for photodynamic therapy owing to its lifetime of 183 h at an intensity of 35 mW/cm^(2).Since OLED patches are required for long-term stable operation in various biomedical applications,we developed an OLED patch with an outcoupling structure using a simple method.The improved OLED patch achieved a 35%increase in light extraction compared to the original OLED patch.展开更多
Currently,there is growing interest in non-antibiotic treatments due to the emergence of multidrug-resistant bacteria.Moreover,photodynamic therapy is advantageous as it is non-invasive and does not lead to resistance...Currently,there is growing interest in non-antibiotic treatments due to the emergence of multidrug-resistant bacteria.Moreover,photodynamic therapy is advantageous as it is non-invasive and does not lead to resistance development.Unlike traditional light therapy platforms,such as light amplification by stimulated emission of radiations(LASERs)and light-emitting diodes(LEDs),organic LEDs(OLEDs)are lightweight,flexible,and compact,enabling real-time treatment in everyday life.Additionally,as a surface-emitting light source,OLEDs deliver a uniform treatment effect over a large area.In this study,we explored the synergistic effect on Staphylococcus aureus(S.aureus)using a natural non-antibiotic material,Sanguisorba officinalis L.extract solution(SO.L.),and 465 nm peak patchable OLEDs depending on both irradiation time and light source area at an intensity of 17 mW/cm^(2).The results confirmed that antibacterial activity increased with light exposure to SO.L.,and further increased as the area of the surface light source expanded.Moreover,the effect was noted with another natural non-antibiotic material.This study validated the non-antibiotic treatment using antibacterial synergistic activity between natural antibacterial phytochemicals and OLEDs and its free-standing antibacterial activity against antibiotic resistance in S.aureus.展开更多
Since flat optics has the feature to implement a compact system,they are widely used in various applications to replace bulky refractive optics.However,they suffer from chromatic aberrations due to dispersion,limiting...Since flat optics has the feature to implement a compact system,they are widely used in various applications to replace bulky refractive optics.However,they suffer from chromatic aberrations due to dispersion,limiting their effectiveness to a narrow wavelength range.Consequently,diffractive optics has been applied for dynamic beam steering within a specific wavelength region or for static steering across multiple wavelengths.This limitation has made it challenging to implement dynamic beam steering in full-color display applications.To address this issue,we developed a multi-wavelength-based optical architecture that mitigates chromatic aberrations.This system incorporates color-selective retarders,half-wave plates,polarization plates,and beam deflectors.We experimentally demonstrated an achromatic beam deflector using a dynamic phase array in transmission mode,achieving continuous tunable beam steering over multiple wavelengths at 460,520,and 638 nm.展开更多
Phototransistors that can detect visible light have been fabricated using solution processed zinc oxide channel/zirconium oxide gate insulator thin film transistors(TFTs)and room temperature synthesized perovskite qua...Phototransistors that can detect visible light have been fabricated using solution processed zinc oxide channel/zirconium oxide gate insulator thin film transistors(TFTs)and room temperature synthesized perovskite quantum dots(PeQDs)as active layer.Typical ZnO thin film transistors did not show a photocurrent under visible light illumination.However,ZnO TFTs decorated with PeQDs exhibited enhanced photocurrent upon exposure to visible light.The device had a responsivity of 567 A/W(617 A/W),a high detectivity of 6.59×10^(13)Jones(1.85×10^(14)J)and a high sensitivity of 10^(7)(10^(8))under green(blue)light at a low drain voltage of 0.1 V.The high photo-responsivity and detectivity under green light resulted from the combination of short ligands in the QDs films and the high mobility of the spray coated ZnO films.Those results are relevant for the development of low cost and low energy consumption phototransistors working in the visible range.展开更多
Stretchable organic light-emitting diodes(SOLEDs)have been the challenging class of OLEDs as they have limited processability to fabricate a design that can withstand external deformation.Herein,we demonstrated the hi...Stretchable organic light-emitting diodes(SOLEDs)have been the challenging class of OLEDs as they have limited processability to fabricate a design that can withstand external deformation.Herein,we demonstrated the highly efficient top-emitting geometrical stretchable OLED(GSOLED)by incorporating the prestretched elastomer with optical adhesive film.The experimental and theoretical characterizations verified the enhancement of device efficiencies with the light extraction phenomenon brought by nanowavy corrugated structures.Furthermore,GSOLED shows stability in stretchable conditions and displays narrower emission spectrum with improved color purity.The full width at half maximum(FWHM)of 21 nm shows narrowband emission with a high current efficiency and EQE of 221 cd A^(−1) and 39.50%.This work marks a significant step forward,providing unprecedented insights into the factors influencing device performance in current and future material systems for stretchable organic light-emitting diodes.展开更多
基金This research project entitled"Development of High-efficient White Organic Light-emitting Diodes for Lighting Application"was supported by Korea Industry Foundation
文摘High-performance blue organic light-emitting diodes （OLEDs） are developed. A concept of using multiple-emissive layer （EML） configuration is adopted. In this letter, bis（2-methyl-8-quinolinolate）-4- （phenylphenolato）A1 （BAlq） and 9,10-di（naphtha-2-yl）anthracene （ADN）, which serve n- and p-type EMLs, respectively, are used to evaluate and demonstrate the multi-EML concept for blue OLEDs. The thickness effect of individual EMLs and the number of EMLs, e.g., triple and quadruple EML components, on the power efficiency of blue OLEDs are systematically investigated. To illustrate the point, the total thickness of the emissive region in different blue OLEDs are kept contact at 30 nm for comparison. The power efficiency of blue OLEDs with a quadruple EML structure of BAlq/ADN/BAlq/ADN is about 40% higher than that of blue OLEDs having a single EML unit. The Commission Internationale deL＇eclairage color coordinates of multi-EML OLEDs have values that represent the average of blue emissions from individual EMLs of BAlq and ADN.
基金supported by the National Creative Research Initiative(CRI)Center for Multi-Dimensional Directed Nanoscale Assembly(2015R1A3A2033061)through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT and Future Planning.
文摘CONSPECTUS:Single-atomic catalyst(SAC)incorporated in graphene plays an increasingly significant role in many applications,including sustainable energy conversion/storage and environmental systems.Such a synergistic structure commonly consisting of atomic metal active sites stabilized on a robust graphene support,is breaking through the intrinsic limitations of precious-metalbased catalysts and broadening a spectrum of applications,while attaining high atom utilization,remarkable novel catalytic activity,and conformational flexibility.Motivated from the unprecedented attractive features of SAC in graphene,enormous research efforts have been devoted to the development of this ultimate catalytic system.For the further advance and eventual success in this field,a general rule for the rational design of SAC is the first prerequisite.Unfortunately,the research effort for the exploration of the fundamental reaction mechanism and rational design principle has been frequently overlooked in spite of the significantly accumulated research efforts thus far.In this Account,we highlight a new perspective for the rational design of SAC in graphene,conceptually centered on the atomistic level heteroelement dopants of graphene.To provide the intuitive viewpoint on the SAC from the scientific perspective,we suggest a new classification scheme for versatile SACs reported thus far into“dopant catalyst”and“dopant-assisted catalyst”,based on the detailed role of dopant in the catalyst system.Thereafter,we highlight the crucial influencing factors on the catalytic activity of the dopant-induced-catalyst system and toward rational designing rule for high performance catalysts.The recent progress in the dopantinduced-catalyst system for a wide spectrum of catalytic applications,including oxygen reduction,oxygen evolution,hydrogen evolution,and CO_(2)reduction is summarized.Finally,we briefly discuss the challenges and opportunities for the future research direction.The exciting expectation for the well-defined,specifically tailored,high performance dopant-induced-catalyst system is anticipated to address global challenges,including climate change,energy crisis and worldwide pandemics.
基金supported by the Technology Innovation Program(20017569Development of substrate materials that can be stretched more than50%for stretchable displays&20018379+2 种基金Development of high-reliability lightemitting fiber-based woven wearable displays)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)supported by the BK21 FOUR(Connected AI Education&Research Program for Industry and Society Innovation,KAIST EE,No.4120200113769)supported by the Technology Development Program(RS-2023-00270443 and RS-2024-00469790)funded by the Ministry of SMEs and Startups(MSS,Korea)。
文摘Numerous studies have aimed to improve the mechanical flexibility of thin-film encapsulation,a key obstacle in commercializing wearable organic light-emitting diodes(OLEDs).This study develops a silbione-blended organic/inorganic hybrid epoxy polymer(hybrimer)with high toughness as an organic barrier to enhance the flexibility of organic-inorganic multi-barriers.The optimal silbioneblended hybrimer(SBH)films exhibit superior mechanical properties,including increased elongation and tensile strength,compared to the hybrimer.The 3.5-dyad SBH-based encapsulation achieves a water vapor transmission rate of 7.83×10^(-6)g/m^(2)/day and 9.45×10^(-5)g/m^(2)/day before and after bending at a strain of 2%,respectively.In addition,the SBH barrier effectively protects the inorganic barrier by forming a robust aluminate phase at the interface between the inorganic and organic barrier,even under harsh conditions of 85℃/85%relative humidity,demonstrating its potential for wearable applications.As a result,SBH-based encapsulations offer mechanical and environmental stability,making them ideal for wearable OLEDs.
基金supported by a National Research Foundation of Korea(NRF)grant,funded by the Korea government(MSIT)(No.2022R1F1A1065534)And,this work was supported by the grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI),funded by the Ministry of Health&Welfare,Republic of Korea(grant number:HI22C0290)Also,this work was supported by the Technology Innovation Program(20018379,Development of high-reliability lightemitting fiber-based woven wearable displays)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘Stretchable organic light-emitting diodes(OLEDs)are emerging as a key technology for next-generation wearable devices due to their uniform light emission,stable performance under stretching conditions,and various flexible substrates.This paper introduces stretchable OLEDs fabricated with laser-cut kirigami patterns and a multifunctional encapsulation multilayer(MEM)barrier.These OLEDs were subsequently transferred onto textiles.These stretchable OLEDs achieved a remarkable stretchability of up to 150%through optimized kirigami pattern and maintained 100%stretchability when integrated with textiles,preserving the flexibility of a textile substrate.Additionally,the MEM barrier provided ultraviolet(UV)reflection and waterproof properties,ensuring reliable performance in harsh environments.Stretchable OLEDs and stretchable fabric OLEDs demonstrated a high luminance of 18,983 cd/m^(2) and 10,205 cd/m^(2),with minimal emission variation under stretched conditions.Furthermore,the potential of stretchable fabric OLEDs for wearable healthcare applications was evaluated by measuring photoplethysmography(PPG)signals.Stable PPG signals were successfully obtained at a 20%stretched state.Adjusting light source intensity effectively compensated for signal quality degradation caused by stretching.These findings highlight the significant potential of stretchable fabric OLEDs for wearable devices and photodiagnostic platforms,offering broad applicability across diverse fields.
基金supported by the Technology Innovation Program(20018379Development of high-reliability light-emitting fiber-based woven wearable displays)funded By the Ministry of Trade,Industry&Energy(MOTIE,Korea)supported by the Technology developmentProgram(RS-2024-00469790)funded by the Ministry of SMEs and Startups(MSS,Korea).
文摘Driven by innovations in the form factor of organic light-emitting diode(OLED)displays,the application scope of OLED technology now encompasses the biomedical field,in addition to its existing application domains of mobile phones,televisions,and lighting.This paper introduces an ultrathin,ultraflexible,and high-power bio-OLED patch with perfect waterproofing and an elongation of 2.04%through material and structural design.Furthermore,the OLED patch with a parallel-stacked OLED delivers a high output of 100 mW/cm^(2),achieves a 40%power density improvement compared to glass-based OLEDs using optimized encapsulation,and is suitable for photodynamic therapy owing to its lifetime of 183 h at an intensity of 35 mW/cm^(2).Since OLED patches are required for long-term stable operation in various biomedical applications,we developed an OLED patch with an outcoupling structure using a simple method.The improved OLED patch achieved a 35%increase in light extraction compared to the original OLED patch.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT,No.2022R1F1A1065534)funded by the grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI)funded by the Ministry of Health&Welfare,Republic of Korea(No.HI22C0290).
文摘Currently,there is growing interest in non-antibiotic treatments due to the emergence of multidrug-resistant bacteria.Moreover,photodynamic therapy is advantageous as it is non-invasive and does not lead to resistance development.Unlike traditional light therapy platforms,such as light amplification by stimulated emission of radiations(LASERs)and light-emitting diodes(LEDs),organic LEDs(OLEDs)are lightweight,flexible,and compact,enabling real-time treatment in everyday life.Additionally,as a surface-emitting light source,OLEDs deliver a uniform treatment effect over a large area.In this study,we explored the synergistic effect on Staphylococcus aureus(S.aureus)using a natural non-antibiotic material,Sanguisorba officinalis L.extract solution(SO.L.),and 465 nm peak patchable OLEDs depending on both irradiation time and light source area at an intensity of 17 mW/cm^(2).The results confirmed that antibacterial activity increased with light exposure to SO.L.,and further increased as the area of the surface light source expanded.Moreover,the effect was noted with another natural non-antibiotic material.This study validated the non-antibiotic treatment using antibacterial synergistic activity between natural antibacterial phytochemicals and OLEDs and its free-standing antibacterial activity against antibiotic resistance in S.aureus.
基金National Research Foundation(NRF)grants(RS-2024-00356928,RS-2024-00462912,RS-2024-00416272,RS-2024-00337012,RS-2024-00408286)funded by the Ministry of Science and ICT(MSIT)of the Korean government.K.W.acknowledges the NRF grant(RS-2023-00280938)funded by the MSIT of the Korean government.
文摘Since flat optics has the feature to implement a compact system,they are widely used in various applications to replace bulky refractive optics.However,they suffer from chromatic aberrations due to dispersion,limiting their effectiveness to a narrow wavelength range.Consequently,diffractive optics has been applied for dynamic beam steering within a specific wavelength region or for static steering across multiple wavelengths.This limitation has made it challenging to implement dynamic beam steering in full-color display applications.To address this issue,we developed a multi-wavelength-based optical architecture that mitigates chromatic aberrations.This system incorporates color-selective retarders,half-wave plates,polarization plates,and beam deflectors.We experimentally demonstrated an achromatic beam deflector using a dynamic phase array in transmission mode,achieving continuous tunable beam steering over multiple wavelengths at 460,520,and 638 nm.
基金This work was supported by the Technology Innovation Program(No.20011317)Development of an adhesive material capable of morphing more than 50%for flexible devices with a radius of curvature of 1 mm or less funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘Phototransistors that can detect visible light have been fabricated using solution processed zinc oxide channel/zirconium oxide gate insulator thin film transistors(TFTs)and room temperature synthesized perovskite quantum dots(PeQDs)as active layer.Typical ZnO thin film transistors did not show a photocurrent under visible light illumination.However,ZnO TFTs decorated with PeQDs exhibited enhanced photocurrent upon exposure to visible light.The device had a responsivity of 567 A/W(617 A/W),a high detectivity of 6.59×10^(13)Jones(1.85×10^(14)J)and a high sensitivity of 10^(7)(10^(8))under green(blue)light at a low drain voltage of 0.1 V.The high photo-responsivity and detectivity under green light resulted from the combination of short ligands in the QDs films and the high mobility of the spray coated ZnO films.Those results are relevant for the development of low cost and low energy consumption phototransistors working in the visible range.
基金supported by the Industrial Strategic Technology Development Program(20014668,20011059,RS-2024-00418116,RS-2024-00417913)through KEIT,funded by the Ministry of Trade,Industry and Energy,Koreasupported by Basic Science Research Program through the NRF,by the Ministry of Science and ICT,Korea(2021R1A2C1008725)BK21 Plus Program(21A20130000018,)funded through the NRF by the Ministry of Education,Korea.
文摘Stretchable organic light-emitting diodes(SOLEDs)have been the challenging class of OLEDs as they have limited processability to fabricate a design that can withstand external deformation.Herein,we demonstrated the highly efficient top-emitting geometrical stretchable OLED(GSOLED)by incorporating the prestretched elastomer with optical adhesive film.The experimental and theoretical characterizations verified the enhancement of device efficiencies with the light extraction phenomenon brought by nanowavy corrugated structures.Furthermore,GSOLED shows stability in stretchable conditions and displays narrower emission spectrum with improved color purity.The full width at half maximum(FWHM)of 21 nm shows narrowband emission with a high current efficiency and EQE of 221 cd A^(−1) and 39.50%.This work marks a significant step forward,providing unprecedented insights into the factors influencing device performance in current and future material systems for stretchable organic light-emitting diodes.
