The Experts below are selected from a list of 10260 Experts worldwide ranked by ideXlab platform

Jinyun Zhou - One of the best experts on this subject based on the ideXlab platform.

Bo Wang - One of the best experts on this subject based on the ideXlab platform.

Jiangshan Chen - One of the best experts on this subject based on the ideXlab platform.

  • C70/C70:pentacene/pentacene organic heterojunction as the Connecting Layer for high performance tandem organic light-emitting diodes: Mechanism investigation of electron injection and transport
    Journal of Applied Physics, 2017
    Co-Authors: Qingxun Guo, Dezhi Yang, Jiangshan Chen, Xianfeng Qiao, Tansir Ahamad, Saad M. Alshehri
    Abstract:

    A high performance tandem organic light-emitting diode (OLED) is realized by employing a C70/C70:pentacene/pentacene organic heterojunction as the efficient charge generation Layer (CGL). Not only more than two time enhancement of external quantum efficiency but also significant improvement in both power efficiency and lifetime are well achieved. The mechanism investigations find that the electron injection from the CGL to the adjacent electron transport Layer (ETL) in tandem devices is injection rate-limited due to the high interface energy barrier between the CGL and the ETL. By the capacitance-frequency (C-F) and low temperature current density-voltage (J-V) characteristic analysis, we confirm that the electron transport is a space-charge-limited current process with exponential trap distribution. These traps are localized states below the lowest unoccupied molecular orbital edge inside the gap and would be filled with the upward shift of the Fermi level during the n-doping process. Furthermore, both t...

  • c70 c70 pentacene pentacene organic heterojunction as the Connecting Layer for high performance tandem organic light emitting diodes mechanism investigation of electron injection and transport
    Journal of Applied Physics, 2017
    Co-Authors: Qingxun Guo, Dezhi Yang, Jiangshan Chen, Xianfeng Qiao, Tansir Ahamad, Saad M. Alshehri
    Abstract:

    A high performance tandem organic light-emitting diode (OLED) is realized by employing a C70/C70:pentacene/pentacene organic heterojunction as the efficient charge generation Layer (CGL). Not only more than two time enhancement of external quantum efficiency but also significant improvement in both power efficiency and lifetime are well achieved. The mechanism investigations find that the electron injection from the CGL to the adjacent electron transport Layer (ETL) in tandem devices is injection rate-limited due to the high interface energy barrier between the CGL and the ETL. By the capacitance-frequency (C-F) and low temperature current density-voltage (J-V) characteristic analysis, we confirm that the electron transport is a space-charge-limited current process with exponential trap distribution. These traps are localized states below the lowest unoccupied molecular orbital edge inside the gap and would be filled with the upward shift of the Fermi level during the n-doping process. Furthermore, both t...

  • Charge generation mechanism of tandem organic light emitting diodes with pentacene/C70 organic heterojunction as the Connecting Layer
    Journal of Materials Chemistry C, 2016
    Co-Authors: Qingxun Guo, Hengda Sun, Jiaxiu Wang, Dezhi Yang, Jiangshan Chen
    Abstract:

    The working mechanism of a planar organic heterojunction based on pentacene/C70 under reverse voltage is studied through current–voltage (I–V) and capacitance–voltage (C–V) measurements. It is found that the pentacene/C70 heterojunction generates large amounts of charges and the charge generation is a tunneling process. The proposed Fowler–Nordheim (F–N) model theoretically demonstrates the I–V properties of the pentacene/C70 heterojunction-based device at different temperatures. The heterojunction interface energy diagram is also well determined by ultraviolet photoemission spectroscopy (UPS) measurements, further elucidating this tunneling process. Moreover, by taking advantage of the large charge generation property of the pentacene/C70 heterojunction, a high efficiency green tandem organic light emitting diode (OLED) is successfully fabricated, where not only the current efficiency is doubled, but also the power efficiency is greatly enhanced, proving the excellent performance of the pentacene/C70 heterojunction as charge generation Layer (CGL). This work highlights the working mechanism of such heterojunction and provides us a new guide to design high performance tandem OLEDs.

  • charge generation mechanism of tandem organic light emitting diodes with pentacene c70 organic heterojunction as the Connecting Layer
    Journal of Materials Chemistry C, 2016
    Co-Authors: Qingxun Guo, Hengda Sun, Jiaxiu Wang, Dezhi Yang, Jiangshan Chen
    Abstract:

    The working mechanism of a planar organic heterojunction based on pentacene/C70 under reverse voltage is studied through current–voltage (I–V) and capacitance–voltage (C–V) measurements. It is found that the pentacene/C70 heterojunction generates large amounts of charges and the charge generation is a tunneling process. The proposed Fowler–Nordheim (F–N) model theoretically demonstrates the I–V properties of the pentacene/C70 heterojunction-based device at different temperatures. The heterojunction interface energy diagram is also well determined by ultraviolet photoemission spectroscopy (UPS) measurements, further elucidating this tunneling process. Moreover, by taking advantage of the large charge generation property of the pentacene/C70 heterojunction, a high efficiency green tandem organic light emitting diode (OLED) is successfully fabricated, where not only the current efficiency is doubled, but also the power efficiency is greatly enhanced, proving the excellent performance of the pentacene/C70 heterojunction as charge generation Layer (CGL). This work highlights the working mechanism of such heterojunction and provides us a new guide to design high performance tandem OLEDs.

Jennifer Rexford - One of the best experts on this subject based on the ideXlab platform.

  • proactive routing in scalable data centers with paris
    ACM Special Interest Group on Data Communication, 2014
    Co-Authors: Dushyant Arora, Theophilus Benson, Jennifer Rexford
    Abstract:

    Modern data centers must scale to a large number of servers, while offering flexible placement and migration of virtual machines. The traditional approach of Connecting Layer-two pods through a Layer-three core constrains VM placement. More recent 'flat' designs are more flexible but have scalability limitations due to flooding/broadcasting or querying directories of VM locations. Rather than reactively learn VM locations, our PARIS architecture has a controller that pre-positions IP forwarding entries in the switches. Switches within a pod have complete information about the VMs beneath them, while each core switch maintains complete forwarding state for part of the address space. PARIS offers network designers the flexibility to choose a topology that meets their latency and bandwidth requirements. We evaluate our PARIS prototype built using OpenFlow-compliant switches and NOX controller. Using PARIS we can build a data center network that supports up to 100K servers.

  • DCC@SIGCOMM - ProActive routing in scalable data centers with PARIS
    Proceedings of the 2014 ACM SIGCOMM workshop on Distributed cloud computing - DCC '14, 2014
    Co-Authors: Dushyant Arora, Theophilus Benson, Jennifer Rexford
    Abstract:

    Modern data centers must scale to a large number of servers, while offering flexible placement and migration of virtual machines. The traditional approach of Connecting Layer-two pods through a Layer-three core constrains VM placement. More recent 'flat' designs are more flexible but have scalability limitations due to flooding/broadcasting or querying directories of VM locations. Rather than reactively learn VM locations, our PARIS architecture has a controller that pre-positions IP forwarding entries in the switches. Switches within a pod have complete information about the VMs beneath them, while each core switch maintains complete forwarding state for part of the address space. PARIS offers network designers the flexibility to choose a topology that meets their latency and bandwidth requirements. We evaluate our PARIS prototype built using OpenFlow-compliant switches and NOX controller. Using PARIS we can build a data center network that supports up to 100K servers.

Saad M. Alshehri - One of the best experts on this subject based on the ideXlab platform.

  • C70/C70:pentacene/pentacene organic heterojunction as the Connecting Layer for high performance tandem organic light-emitting diodes: Mechanism investigation of electron injection and transport
    Journal of Applied Physics, 2017
    Co-Authors: Qingxun Guo, Dezhi Yang, Jiangshan Chen, Xianfeng Qiao, Tansir Ahamad, Saad M. Alshehri
    Abstract:

    A high performance tandem organic light-emitting diode (OLED) is realized by employing a C70/C70:pentacene/pentacene organic heterojunction as the efficient charge generation Layer (CGL). Not only more than two time enhancement of external quantum efficiency but also significant improvement in both power efficiency and lifetime are well achieved. The mechanism investigations find that the electron injection from the CGL to the adjacent electron transport Layer (ETL) in tandem devices is injection rate-limited due to the high interface energy barrier between the CGL and the ETL. By the capacitance-frequency (C-F) and low temperature current density-voltage (J-V) characteristic analysis, we confirm that the electron transport is a space-charge-limited current process with exponential trap distribution. These traps are localized states below the lowest unoccupied molecular orbital edge inside the gap and would be filled with the upward shift of the Fermi level during the n-doping process. Furthermore, both t...

  • c70 c70 pentacene pentacene organic heterojunction as the Connecting Layer for high performance tandem organic light emitting diodes mechanism investigation of electron injection and transport
    Journal of Applied Physics, 2017
    Co-Authors: Qingxun Guo, Dezhi Yang, Jiangshan Chen, Xianfeng Qiao, Tansir Ahamad, Saad M. Alshehri
    Abstract:

    A high performance tandem organic light-emitting diode (OLED) is realized by employing a C70/C70:pentacene/pentacene organic heterojunction as the efficient charge generation Layer (CGL). Not only more than two time enhancement of external quantum efficiency but also significant improvement in both power efficiency and lifetime are well achieved. The mechanism investigations find that the electron injection from the CGL to the adjacent electron transport Layer (ETL) in tandem devices is injection rate-limited due to the high interface energy barrier between the CGL and the ETL. By the capacitance-frequency (C-F) and low temperature current density-voltage (J-V) characteristic analysis, we confirm that the electron transport is a space-charge-limited current process with exponential trap distribution. These traps are localized states below the lowest unoccupied molecular orbital edge inside the gap and would be filled with the upward shift of the Fermi level during the n-doping process. Furthermore, both t...