Since most organic materials are very sensitive to moisture and oxygen, organic light emitting diodes (OLEDs) require an encapsulation layer to protect the active layer from these gases. Since light, flexible and port...Since most organic materials are very sensitive to moisture and oxygen, organic light emitting diodes (OLEDs) require an encapsulation layer to protect the active layer from these gases. Since light, flexible and portable OLEDs are being employed in more diverse climates and environmental conditions, the OLED encapsulation layer must retain robust mechanical properties and stability in high temperature/high humidity conditions. Al2O3 films have demonstrated excellent barrier performance, but they readily hydrolyze when exposed to prolonged harsh environments. In this study, we fabricated a thin film encapsulation (TFE) film that was resistant to hydrolysis, using Al2O3/MgO (AM) nanolaminates. MgO has superior resistance to harsh environments, and the aluminate phase generated by the chemical reaction of Al2O3 and MgO provided excellent barrier performance, even after storage in harsh conditions. A multi-barrier fabricated using the AM nanolaminate showed excellent barrier performance, close to the level required by OLEDs. It did not significantly deteriorate even after a bending test of 1,000 iterations at 0.63% strain. After 1,000 cycle of bending, the electrical properties of the passivated OLEDs were not significantly degraded at shelf-lifetime test where the fabricated device was stored for 50 days in a harsh environment of 60℃, 90% relative humidity. The multi-barrier shows the best performance compared to previous studies on flexible encapsulation that can be used in harsh environments.展开更多
Transition metal sulfides(TMS)hold great promise as anode materials for Li^(+)/Na^(+)storage.However,their practical application still faces several challenges,such as inadequate electrical conductivity,substantial vo...Transition metal sulfides(TMS)hold great promise as anode materials for Li^(+)/Na^(+)storage.However,their practical application still faces several challenges,such as inadequate electrical conductivity,substantial volume changes and a propensity for agglomeration.To tackle these challenges,a 3D composite structure composed of graphene nanosheets crosslinked core−shell FeS_(2)@N,S co−doped porous carbon(FeS_(2)@NSC/GNs)is created by combining self−template polymerization with the graphene encapsulation technique.Systematic characterization and analysis demonstrate the effectiveness of the self−template polymerization strategy in generating a porous core−shell structure,which facilitates the uniform dispersion and optimal contact of the FeS_(2) core within the carbon shell.Concurrently,the integration of graphene,alongside the porous carbon shell,introduces a sophisticated dual−protection mechanism against volume expansion and undesirable FeS_(2) aggregation.Furthermore,the resulting 3D architecture enables efficient electron/ion transport and provides abundant sites for Li^(+)/Na^(+)storage.Leveraging these inherent benefits,the FeS_(2)@NSC/GNs composite exhibits significantly improved lithium/sodium storage performance in comparison to the counterparts.Evidently,our proposed approach offers valuable guidance for the construction of advanced anodes for lithium/sodium−ion batteries.展开更多
An encapsulation-structured Fe_(2)O_(3)@mesoZSM-5(Fe@MZ5)was fabricated by confining Fe_(2)O_(3) nanoparticles(ca.4 nm)within the ordered mesopores of hierarchical ZSM-5 zeolite(meso-ZSM-5),with ferric oleate and amph...An encapsulation-structured Fe_(2)O_(3)@mesoZSM-5(Fe@MZ5)was fabricated by confining Fe_(2)O_(3) nanoparticles(ca.4 nm)within the ordered mesopores of hierarchical ZSM-5 zeolite(meso-ZSM-5),with ferric oleate and amphiphilic organosilane as the iron source and meso-porogen,respectively.For comparison,catalysts with Fe_(2)O_(3)(ca.12 nm)encapsulated in intra-crystal holes of meso-ZSM-5 and with MCM-41 or ZSM-5 phase as the shell were also prepared via sequential desilication and recrystallization at different pH values and temperatures.Catalytic phenol hydroxylation performance of the as-prepared catalysts using H_(2)O_(2) as oxidant was compared.Among the encapsulation-structured catalysts,Fe@MZ5 showed the highest phenol conversion and hydroquinone selectivity,which were enhanced by two times compared to the Fe-oxide impregnated ZSM-5(Fe/Z5).Moreover,the Fe-leaching amount of Fe@MZ5 was only 3% of that for Fe/Z5.The influence of reaction parameters,reusability,and ·OH scavenging ability of the catalysts were also investigated.Based on the above results,the structure-performance relationship of these new catalysts was preliminarily described.展开更多
Ciphertext-policy attribute-based encryption(CP-ABE)is a promising cryptographic solution to the problem for enforcing fine-grained access control over encrypted data in the cloud.However,when applying CP-ABE to data ...Ciphertext-policy attribute-based encryption(CP-ABE)is a promising cryptographic solution to the problem for enforcing fine-grained access control over encrypted data in the cloud.However,when applying CP-ABE to data outsourcing scenarios,we have to address the challenging issue of policy updates because access control elements,such as users,attributes,and access rules may change frequently.In this paper,we propose a notion of access policy updatable ciphertext-policy attribute-based encryption(APU-CP-ABE)by combining the idea of ciphertext-policy attribute-based key encapsulation and symmetric proxy re-encryption.When an access policy update occurs,data owner is no longer required to download any data for re-encryption from the cloud,all he needs to do is generate a re-encryption key and produce a new encapsulated symmetric key,and then upload them to the cloud.The cloud server executes re-encryption without decryption.Because the re-encrypted ciphertext is encrypted under a completely new key,users cannot decrypt data even if they keep the old symmetric keys or parts of the previous ciphertext.We present an APU-CP-ABE construction based on Syalim et al.’s[Syalim,Nishide and Sakurai(2017)]improved symmetric proxy re-encryption scheme and Agrawal et al.’s[Agrawal and Chase(2017)]attribute-based message encryption scheme.It requires only 6 bilinear pairing operations for decryption,regardless of the number of attributes involved.This makes our construction particularly attractive when decryption is time-critical.展开更多
基金This research was supported by the Engineering Research Center of Excellence(ERC)Program supported by the National Research Foundation(NRF)of the Korean Ministry of Science,ICT&Future Planning(MSIP)(Grant No.NRF-2017R1A5A1014708).The authors express sincere gratitude to National NanoFab(NNFC)for the measurements.We also thank Prof.Byeong:Soo Bae from KAIST for help in synthesis of the polymers.
文摘Since most organic materials are very sensitive to moisture and oxygen, organic light emitting diodes (OLEDs) require an encapsulation layer to protect the active layer from these gases. Since light, flexible and portable OLEDs are being employed in more diverse climates and environmental conditions, the OLED encapsulation layer must retain robust mechanical properties and stability in high temperature/high humidity conditions. Al2O3 films have demonstrated excellent barrier performance, but they readily hydrolyze when exposed to prolonged harsh environments. In this study, we fabricated a thin film encapsulation (TFE) film that was resistant to hydrolysis, using Al2O3/MgO (AM) nanolaminates. MgO has superior resistance to harsh environments, and the aluminate phase generated by the chemical reaction of Al2O3 and MgO provided excellent barrier performance, even after storage in harsh conditions. A multi-barrier fabricated using the AM nanolaminate showed excellent barrier performance, close to the level required by OLEDs. It did not significantly deteriorate even after a bending test of 1,000 iterations at 0.63% strain. After 1,000 cycle of bending, the electrical properties of the passivated OLEDs were not significantly degraded at shelf-lifetime test where the fabricated device was stored for 50 days in a harsh environment of 60℃, 90% relative humidity. The multi-barrier shows the best performance compared to previous studies on flexible encapsulation that can be used in harsh environments.
基金financially supported by the Science and Technology Talents Lifting Project of Hunan Province(No.2022TJ-N16)the Natural Science Foundation of Hunan Province(Nos.2024JJ4022,2023JJ30277,2023JJ50043)+1 种基金the Science and Technology Innovation Program of Hunan Province(No.2022RC3037)the China Postdoctoral Fellowship Program(GZC20233205).
文摘Transition metal sulfides(TMS)hold great promise as anode materials for Li^(+)/Na^(+)storage.However,their practical application still faces several challenges,such as inadequate electrical conductivity,substantial volume changes and a propensity for agglomeration.To tackle these challenges,a 3D composite structure composed of graphene nanosheets crosslinked core−shell FeS_(2)@N,S co−doped porous carbon(FeS_(2)@NSC/GNs)is created by combining self−template polymerization with the graphene encapsulation technique.Systematic characterization and analysis demonstrate the effectiveness of the self−template polymerization strategy in generating a porous core−shell structure,which facilitates the uniform dispersion and optimal contact of the FeS_(2) core within the carbon shell.Concurrently,the integration of graphene,alongside the porous carbon shell,introduces a sophisticated dual−protection mechanism against volume expansion and undesirable FeS_(2) aggregation.Furthermore,the resulting 3D architecture enables efficient electron/ion transport and provides abundant sites for Li^(+)/Na^(+)storage.Leveraging these inherent benefits,the FeS_(2)@NSC/GNs composite exhibits significantly improved lithium/sodium storage performance in comparison to the counterparts.Evidently,our proposed approach offers valuable guidance for the construction of advanced anodes for lithium/sodium−ion batteries.
基金supported by the National Science Foundation of Jilin Province(No.20200201208JC).
文摘An encapsulation-structured Fe_(2)O_(3)@mesoZSM-5(Fe@MZ5)was fabricated by confining Fe_(2)O_(3) nanoparticles(ca.4 nm)within the ordered mesopores of hierarchical ZSM-5 zeolite(meso-ZSM-5),with ferric oleate and amphiphilic organosilane as the iron source and meso-porogen,respectively.For comparison,catalysts with Fe_(2)O_(3)(ca.12 nm)encapsulated in intra-crystal holes of meso-ZSM-5 and with MCM-41 or ZSM-5 phase as the shell were also prepared via sequential desilication and recrystallization at different pH values and temperatures.Catalytic phenol hydroxylation performance of the as-prepared catalysts using H_(2)O_(2) as oxidant was compared.Among the encapsulation-structured catalysts,Fe@MZ5 showed the highest phenol conversion and hydroquinone selectivity,which were enhanced by two times compared to the Fe-oxide impregnated ZSM-5(Fe/Z5).Moreover,the Fe-leaching amount of Fe@MZ5 was only 3% of that for Fe/Z5.The influence of reaction parameters,reusability,and ·OH scavenging ability of the catalysts were also investigated.Based on the above results,the structure-performance relationship of these new catalysts was preliminarily described.
基金This research is funded by Science and Technology Program of Guangzhou(Grant No.201707010358).
文摘Ciphertext-policy attribute-based encryption(CP-ABE)is a promising cryptographic solution to the problem for enforcing fine-grained access control over encrypted data in the cloud.However,when applying CP-ABE to data outsourcing scenarios,we have to address the challenging issue of policy updates because access control elements,such as users,attributes,and access rules may change frequently.In this paper,we propose a notion of access policy updatable ciphertext-policy attribute-based encryption(APU-CP-ABE)by combining the idea of ciphertext-policy attribute-based key encapsulation and symmetric proxy re-encryption.When an access policy update occurs,data owner is no longer required to download any data for re-encryption from the cloud,all he needs to do is generate a re-encryption key and produce a new encapsulated symmetric key,and then upload them to the cloud.The cloud server executes re-encryption without decryption.Because the re-encrypted ciphertext is encrypted under a completely new key,users cannot decrypt data even if they keep the old symmetric keys or parts of the previous ciphertext.We present an APU-CP-ABE construction based on Syalim et al.’s[Syalim,Nishide and Sakurai(2017)]improved symmetric proxy re-encryption scheme and Agrawal et al.’s[Agrawal and Chase(2017)]attribute-based message encryption scheme.It requires only 6 bilinear pairing operations for decryption,regardless of the number of attributes involved.This makes our construction particularly attractive when decryption is time-critical.
