The demonstration of hybrid n-ZnO nanorod/p-polymer heterojunction light emitting diodes on glass substrates

We report a demonstration of heterojunction light emitting diode (LED) based on a hybrid n-ZnO-nanorod/p-polymer layered structure. The ZnO was grown using the aqueous chemical growth (ACG) on top of the polymer(s) which were deposited on glass. The current–voltage (I–V) behavior of the heterojunctions showed good rectifying diode characteristics. Room-temperature electroluminescence (EL) spectra of the LEDs provided a broad emission band over a wide LED color range (430–650 nm), in which both zinc and oxygen vacancy peaks are clearly detected. We present here luminescent devices based on the use of ZnO-nanorods in combination with two different blended and multi-layered p-type polymers. Electroluminescence of the first batch of devices showed that white bluish strong emission for the presently used polymers is clearly observed. We obtained a turn-on voltage of 3 V and break-down voltage equal to −6 V for PVK-TFB blended device. The corresponding values for the NPD-PFO multilayer device were 4 V and −14 V, respectively. The rectification factors were equal to 3 and 10 for the two devices, respectively. The films and devices processed were characterized by scanning electron microscopy (SEM), DEKTAK 3ST Surface Profile, Semiconductor Parameter Analyzer, photoluminescence (PL), and electroluminescence (EL).