Browsing by Subject "Hole Injection"

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    Improved performance of organic light-emitting diodes with MoO3 interlayer by oblique angle deposition
    (Optical Society of America, 2011) Liu, S. W.; Divayana, Y.; Sun, X. W.; Wang, Y.; Leck, K. S.; Demir, Hilmi Volkan
    We fabricated and demonstrated improved organic light emitting diodes (OLEDs) in a thin film architecture of indium tin oxide (ITO)/molybdenum trioxide (MoO3) (20 nm)/ N,N'-Di(naphth-2-yl)-N,N'-diphenyl-benzidine (NPB) (50 nm)/tris-(8-hydroxyquinoline) (Alq(3)) (70 nm)/Mg:Ag (200 nm) using an oblique angle deposition technique by which MoO3 was deposited at oblique angles (theta) with respect to the surface normal. It was found that, without sacrificing the power efficiency of the device, the device current efficiency and external quantum efficiency were significantly enhanced at an oblique deposition angle of theta = 60 degrees for MoO3. (C) 2011 Optical Society of America
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    Influence of n-type versus p-type AlGaN electron-blocking layer on InGaN/GaN multiple quantum wells light-emitting diodes
    (AIP Publishing, 2013-08-01) Ji Y.; Zhang Z.-H.; Kyaw, Z.; Tan S.T.; Ju, Z. G.; Zhang, X. L.; Liu W.; Sun, X. W.; Demir, Hilmi Volkan
    The effect of n-AlGaN versus p-AlGaN electron-blocking layers (EBLs) on the performance of InGaN/GaN light-emitting diodes is studied in this work. Experimental results suggest that the n-type EBL leads to higher optical output power and external quantum efficiency, compared to the devices with p-AlGaN EBL, which is commonly used today. Numerical simulations on the carrier distribution and energy band diagram reveal that the n-AlGaN EBL is more efficient in preventing electron overflow, while not blocking the hole injection into the active region, hence leading to higher radiative recombination rate within the multiple quantum wells active region. © 2013 AIP Publishing LLC.