Polymer/ZnO Micro-Nano Array Composites for Light-Emitting Layer of Flexible Optoelectronic Devices

We prepared PAM/ZnO micro-nano arrays on indium tin oxide (ITO) conductive films based on poly(ethylene terephthalate) (PET) substrates (PET/ITO) by a low cost and low temperature chemical solution approach. The morphology and crystal structure of the nanorod arrays were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the ordered arrays of the ZnO and PAM/ZnO arrays grew vertically on the substrates and revealed that the nanorods grew along the [0001] direction of the ZnO crystallites. SEM images showed that most of the ZnO arrays had an average diameter of 150 nm and their typical length was about 3 μm. The optical properties of the ZnO and PAM/ZnO micro-nano arrays were characterized by photoluminescence at room temperature. The growth mechanism of the PAM/ZnO arrays and their possible application in flexible optoelectronic devices are discussed. Defect peaks of the blue peak at 457 nm and the green peak at 530 nm were observed in the photoluminescence (PL) spectrum of the ZnO micro-nano arrays in the absence of PAM. The blue and green emissions are attributed to electron transitions from the extended state Zn_i to the valance band and from the conduction band to antisite oxygen (O_Zn), respectively. The PAM/ZnO arrays only had a UV peak at 400 nm, and this was caused by electron transitions from the interstitial Zn (Zn_i) to the valance band. Flexible PAM/ZnO devices with good diode characteristics are suitable for flexible optoelectronic applications.