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Charge generation junction (CGJ) is widely used in tandem organic light emitting diodes (OLEDs), mainly fabricated by vacuum deposition. But solution processed CGJs are used for quantum-dot light emitting diodes (QLEDs). It is demonstrated in this work that the QLEDs with top and bottom CGJs have similar device performance with conventional QLED. The current and power efficiencies of the QLED with top and bottom CGLs are almost independent on the work function of cathode metal, which demonstrates the effectiveness of the CGJs. Double stack QLED is designed and fabricated with the same three CGJs with 3 kinds of materials and two different quantum-dots materials.

We report in this wok the improvement of current efficiency (CE) roll-off and power efficiency (PE) roll-off of QLED by shell engineering of quantum-dots (QDs). The inverted QLEDs using the green QDs (G-QDs) with optimized shell exhibited the extremely reduced CE roll-off of 9% at 10,000 cd/m2 and also 10 times longer lifetime compared with the QLED with conventional G-QDs.

An inverted tandem quantum-dot light-emitting diode (QLEDs) is demonstrated using solution processed charge generation layers (CGLs) for the first time. The tandem QLEDs with the CGL, consisting of green QDs (G-QDs) for bottom and red QDs (R-QDs) for top cells, exhibited yellow emission with current efficiency of 15.9 cd/A at 1,000 cd/m2.

We reviewed n- and p-type metal oxides for quantum-dot light-emitting diode (QLED) application. N-type metal oxides such as ZnO, Al doped ZnO and Cs2CO3 doped ZnO and Li doped ZnO could be used for electron injection/transport layer and p-type oxides such as NiOx, doped NiOx, CuOx, SnO for hole injection/transport layer. And, the metal oxide n-p junction can be also used as charge generation layer for QLED. We have applied these n-type and p-type metal oxides for QLEDs.

Objective Limited research has examined the quality of life (QOL) and its correlates among family caregivers (FCs) during the final stage of terminal cancer. The purpose of this study was to investigate the determinants of overall QOL and its subdomains among Korean FCs at the very end of life. Methods For this cross-sectional study, we enrolled 299 FCs of terminal cancer patients from seven palliative care units. To assess FCs' QOL and its predictors, we used the Caregiver Quality Of Life Index-Cancer, which contains four domains. Possible determinants of caregiver QOL were categorized into patient, caregiver, and environmental factors. A multiple regression model was used to identify factors associated with FCs' QOL. Results Variance in each Caregiver Quality Of Life Index-Cancer domain was explained by different factors. FCs of younger patient felt more burden but were more likely to adapt positively. Emotional distress of FCs was strongly associated with total QOL, burdensomeness, and disruptiveness. Positive adaptation was related to more visits for care, FCs' religiousness, more social support, and satisfactory perceived quality of care. Financial concerns were more likely in married FCs, FCs with less social support, or low incomes. Conclusion Emotional distress of FCs was the most important factor determining the overall and negative aspects of FCs' QOL, whereas various environmental factors were associated with positive coping. Appropriate support programs directed at these factors are needed to maintain and improve FCs' QOL. Copyright © 2015 John Wiley & Sons, Ltd.

We report the design and fabrication of a high resolution AMOLED with integrated gate driver using bulk-accumulation amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) on a plastic substrate. The gate driver consisting 7 TFTs and 1 capacitor is small in physical size which is only 40 µm in width (pitch). At the supply voltage (VDD) of 20 V, the clock frequency of the gate driver approaches 250 kHz, corresponding to a pulse width of 2 µs. The gate driver could be operated under mechanical bending radius of 2mm, making it applicable to flexible high resolution active-matrix displays. The demonstrated AMOLED on flexible substrate achieves good image quality with very high resolution.

We report the solution processed charge generation layers (CGLs) used for inverted quantum-dot light emitting diodes (QLEDs). The inverted green, yellow and red QLEDs with solution processed CGLs exhibit the maximum current efficiency (CEmax) of 19.2, 13.6 and 6.1 cd/A, respectively. Therefore, solution processed CGL can be used for low cost QLEDs with high efficiency.

We studied the solution processed vanadium pentoxide (V2O5) doping effect in PEDOT:PSS for use in hole injection layer (HIL), and as a result, V2O5 doped PEDOT:PSS improved the performance of polymer light-emitting diode (PLED) significantly. The improvement is related to the increased conductivity of PEDOT:PSS by V2O5 doping. This improvement enhances hole injection into the emission layer, and it will improve the charge balance. The PLED with PEDOT:PSS HIL and super yellow polymer has maximum current and power efficiencies of 12.01 cd A−1 and 9.67 lm W−1, respectively. On the other hand, the device with V2O5 (10:1) doped PEDOT:PSS indicates the maximum current and power efficiencies of 15.12 cd A−1 and 12.66 lm W−1, respectively, indicating that the efficiencies increase over 20% compared to the control device. The leakage currents of the PLED decrease to ∼10% of the control PLED. Note also that V2O5 suppressed the diffusion of indium from anode to PEDOT:PSS, and also prevented the acidic damage from sulfate ions of PEDOT:PSS to IZO and active layer.

We present the first display panels exploiting the nVerPix CN-VOLET technology that reduces the pixel circuit of the conventional AMOLED display to two discrete components: the switching transistor and the CN-VOLET. This permits high aperture ratio bottom emission displays—as high as 70% here— and greatly simplifies the manufacturing. Mono-color QVGA AMOLED displays (6.4 cm diagonal) playing video will be shown.

Quick View Other Sources By Kim, Hyeong Pil; Kim, Jeongmo; Kim, Byung Soon; Kim, Hyo-Min; Kim, Jeonggi; bin Mohd. Yusoff, Abd. Rashid; Jang, Jin; Nazeeruddin, Mohammad Khaja From Advanced Optical Materials (2017), Ahead of Print.

We report the state-of-art technologies of quantum-dot light-emitting diodes, focused on the current and power efficiencies. And our recent results on QLEDs are also added. A high-efficiency inverted green quantum-dot light emitting diodes (QLEDs) was demonstrated in ADRC using stacked electron transporting layer (ETL), exhibiting maximum current efficiency of 28.29 cd/A and power efficiency of 22.11 lm/W, respectively. The additional ETL layer could improve the device performance by around 3 times compare to that of a QLED with single ETL.

A semi-transparent inverted quantum dot light emitting diode (QLED) is demonstrated using tri-layer QDs, exhibiting bottom emission of 6,485 cd/m2 and top emission of 1,911 cd/m2. And its transmittance in the visible region is ∼30 % with 18 nm Ag top semi-transparent electrode.