A double insulation layer structure organic thin films transistor （OTFT） was investigated for improving the performance of the SiO2 gate insulator. A 50 nm PMMA layer was coated on top of the SiO2 gate insulator as ...
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A double insulation layer structure organic thin films transistor （OTFT） was investigated for improving the performance of the SiO2 gate insulator. A 50 nm PMMA layer was coated on top of the SiO2 gate insulator as the organic insulator layer. The results demonstrated that using inorganic/organic compound insulator as the gate dielectric layer is an effective method to fabricate OTPTs with improved electric characteristics and decreased leakage current. Electrical parameters of carrier mobility and on/off ratio were calculated. OTPT based on Si substrate with a field-effect mobility of 4.0 × 10^-3cm^2/Vs and on/off ratio of l0^4 was obtained.
Buffer layer is a crucial issue for driving voltage, efficiency and stability of OLEDs Several buffer layers were used in Top-OLED (TOLED) and Bottom-OLEDs (BOLED) for comparison. It is found that starburst material m...
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ISBN:
(纸本)9787561752289
Buffer layer is a crucial issue for driving voltage, efficiency and stability of OLEDs Several buffer layers were used in Top-OLED (TOLED) and Bottom-OLEDs (BOLED) for comparison. It is found that starburst material mMTDATA based devices exhibited much high current efficiency than others, while metal oxide MoOx showed superior characteristics of low driving voltage and much long lifetime of devices. By combining the measurement of work function of the metal oxide, using a method of contact potential difference previously reported by us, with the investigation of relative Hole-only or Electron-only devices, the mechanism of formed low driving voltage, high efficiency and high stability were analyzed.
Compared to the conventional hetero-junction OLED (Cell-HJ), a blue OLED with a graded junction in the interface between hole transporting layer (HTL) and emitted layer (EML) exhibited low drive voltage and significan...
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ISBN:
(纸本)9787561752289
Compared to the conventional hetero-junction OLED (Cell-HJ), a blue OLED with a graded junction in the interface between hole transporting layer (HTL) and emitted layer (EML) exhibited low drive voltage and significantly improved stability, however loss of efficiency. In order to redeem the decrease in efficiency, a step barrier for electron injection was proposed. The device with a graded junction in side of anode and a step barrier in the side of cathode showed high stability and improved efficiency. By studying Hole-only devices with graded junction and hetero-junction, electron-only cell with a step barrier, the enhancement of stability and improvement of efficiency have been explained.
We demonstrated efficient electron injection and transport in organic light-emitting diodes using an electron-transport layer composed of 4, 7-diphenyl-1, 10-phenanthroline (BPhen) with 8-hydroxy-quinolinato lithium (...
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ISBN:
(纸本)9787561752289
We demonstrated efficient electron injection and transport in organic light-emitting diodes using an electron-transport layer composed of 4, 7-diphenyl-1, 10-phenanthroline (BPhen) with 8-hydroxy-quinolinato lithium (Liq) co-deposited layer. Based on cohost strategy, a low-voltage driving of OLEDs with the structure of [ ITO/m-MTDATA/NPB/Alq/Liq (33%) : Bphen/LiF/Al] has been achieved. It is found that the power efficiency is enhanced by ∼ 20% while driving voltage is reduced by ∼ 15% as compared to the control device. Therefore this strategy with the judicial doping concentration of Liq greatly increases the electron conductivity in ETL, leading to the lowering the operating voltage and enhancing the power efficiency of the OLEDs.
The electron injection transportation in OLEDs were improved by using a Gaq layer between Alq (or Bphen) and TBADN as step barrier. Since the LUMO (Lowest Unoccupied Molecular Orbital) of Gaq (2.9 eV) lies in between ...
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ISBN:
(纸本)9787561752289
The electron injection transportation in OLEDs were improved by using a Gaq layer between Alq (or Bphen) and TBADN as step barrier. Since the LUMO (Lowest Unoccupied Molecular Orbital) of Gaq (2.9 eV) lies in between that of Alq (3.1 eV) (or Bphen (3.0 eV)) and TBADN (2.8 eV), step barrier from Alq (or BPhen) though Gaq to TBADN can be formed. The experimental results indicate that: The J-V characteristics of both the electron only and the complete devices show the increase of the current density in devices with step barrier compared with the devices without step barrier. For electron only devices, the driving voltage at the current density of 20 mA/cm2 were reduced from 7.9 V to 4.9 V for devices with Alq, and from 4.2 V to 3.1 V for devices with Bphen respectively owing to the introduce of step barrier. For the complete devices, after Gaq step barrier was introduced, at 20 mA/cm2, the driving voltage were reduced from 7 V to 5. 8 V for devices with Alq and from 6.2 V to 5.1 V for devices with Bphen. When step barrier was introduced, the luminance at 200 mA/cm2 were increased from 1684 cd/m2 to 2 736 cd/m2 for device with Alq, and from 1026 cd/m2 to 2466 cd/m2 for devices with BPhen respectively. The phenomena were explained by using tunnel theory.
An organic thin-film transistor (OTFTs) having MoO3/Al electrode and OTS/SiO2 bilayer gate insulator configuration between gate insulator and source/drain electrodes is investigated. Thermal SiO2 layer grown is used a...
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ISBN:
(纸本)9787561752289
An organic thin-film transistor (OTFTs) having MoO3/Al electrode and OTS/SiO2 bilayer gate insulator configuration between gate insulator and source/drain electrodes is investigated. Thermal SiO2 layer grown is used as the OTFT gate dielectric;Copper phthalocyanine(CuPc) is used as an active layer. We have found that using silane coupling agents-octade-cyltrichlorosilane (OTS) to reduce the surface energy of the SiO2 gate dielectric and significantly improve device performance. This OTS/SiO2 bilayer gate insulator configuration increases the field-effect mobility, reduces the threshold voltage, and improves the on/off ratio at the same time. The device with MoO3/AI electrode had similar Ids compared to the device with Au electrode at same gate voltage. MoO3/AI was proved to be a superior electrode. Our results indicate that using double-layer of electrode and double-layer of insulator is an effective way to improve OTFT performance.
H.264 allows motion estimation performing on multiple reference frames. This new feature improves the prediction accuracy of inter-coding blocks significantly. However, the coding gain comes at the cost of a much high...
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H.264 allows motion estimation performing on multiple reference frames. This new feature improves the prediction accuracy of inter-coding blocks significantly. However, the coding gain comes at the cost of a much higher computational complexity. The reference software JM adopts full search scheme, and the computational complexity of motion estimation increases linearly with the number of allowed reference frames. In fact, the reduction of prediction residues is highly dependent on the nature of sequences, not on the number of searched frames. In this paper, with consideration of video nature and the available information from previous searched reference frames, an adaptive multi-frame selection algorithm (AMFSA) is proposed to speed up the matching process for multiple reference frames in the H.264 video coding system. The proposed algorithm can effectively reduce 63.6% on average.
H.264 employs 7 different size block types for motion estimation that can significantly improve the coding performance compared with the previous video coding standards. However, H.264 requires extremely high computat...
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H.264 employs 7 different size block types for motion estimation that can significantly improve the coding performance compared with the previous video coding standards. However, H.264 requires extremely high computation with the R-D optimized decision since so many prediction modes are used. In this paper, a novel inter mode decision algorithm (NIMDA) is proposed that utilizes SADs of each 4X4 block and texture characteristic to reduce the candidate mode set after the 16 X16 prediction mode is tested. The simulation results show that the proposed algorithm reduces the entire encoding time by 64.52% with only negligible coding loss.
Aiming at fully exploiting the temporal redundancy and spatial redundancy, we propose a multi-view video coding scheme based on resultant vector estimation. Combining the disparity vector and motion vector as one vect...
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ISBN:
(纸本)9780863418365
Aiming at fully exploiting the temporal redundancy and spatial redundancy, we propose a multi-view video coding scheme based on resultant vector estimation. Combining the disparity vector and motion vector as one vector, the novel "resultant vector" was first proposed. Meanwhile, by extending the loop constraint to multi-view images for a parallel camera geometry model, redundancy between views is greatly reduced by utilizing the linear relationship of adjacent views and the "resultant vector". Experimental results show that our scheme's performance is superior to conventional methods such as GOP (Group-of-picture) or M-picture. Coding efficiency is improved about 1.2-1.5 dB.
Since the current rate control schemes in H.264 do not present the capability of efficient GOP-level bit allocation, the video quality varies greatly for sequences with the scene change or the scene complexity varying...
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ISBN:
(纸本)9780863418365
Since the current rate control schemes in H.264 do not present the capability of efficient GOP-level bit allocation, the video quality varies greatly for sequences with the scene change or the scene complexity varying from one GOP to another. To overcome the limitation, we propose a novel rate control scheme based on incremental PID algorithm. The incremental PID algorithm is introduced to minimize video quality variations in GOP-level bit allocation. Extensive simulation results show that the proposed rate control scheme, without expensive computational complexity added, decreases the average video quality variations by 15.07%.
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