Ultraviolet electroluminescence from ZnO/polymer heterojunction light-emitting diodes.
We report ultraviolet electroluminescence at 390 nm from diode structures consisting of electrodeposited ZnO nanorods sandwiched between a transparent SnO(2) film and a p-type conducting polymer. The nanorods are embedded in an insulating polystyrene layer. ZnO deposition occurs at 90 degrees C and produces vertically oriented nanorods with very high uniformity over areas of approximately 20 cm(2). Electron diffraction shows the nanorods to be single crystalline wurtzite ZnO. As-grown films show a broad electroluminescence band over the visible spectrum. Annealing at moderate temperatures (T = 300 degrees C) increases the emission and strongly raises the excitonic contribution. Optimally processed films show a narrow ultraviolet electroluminescence line at approximately 390 nm.
Könenkamp
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Physics Department, Portland State University, 1719 Southwest 10th Avenue, Portland, OR 97201, USA. rkoe@pdx.edu
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Godinez
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