Correlation Study of Structural and Optical Properties of ZnO/PTAA Hybrid Heterojunction Layer

Abstract

Zinc Oxide (ZnO) thin films have been deposited onto an ITO glass by RF sputtering method in a controlled condition followed by a layer of Poly(triarylamine) as an electron acceptor to form a hybrid-heterojunction thin film. In this work, Poly(triarylamine) is deposited by using spin coating method at different spin rate ranging from 1000 RPM to 5000 RPM. The correlation between the structural and optical properties of this hybrid heterojunction were investigated. The crystallographic structure of ZnO and PTAA is analysed by obtaining its Full width half maximum and grain size value by using X-ray diffractometer. UV-Vis result strongly reveal that all the thin films exhibits high transparency (>80%) in visible region with wide band gap of 3.38 eV for ZnO and 3.1 eV for PTAA at 5000 RPM sintering. Surface morphology of the hybrid film is observed using an advance material microscope (HIROX) with 3 different lenses of low range, mid-range and high range. It is shown that, as the RPM speed is increasing the distribution of PTAA on the ZnO layer is smoother and uniform. The correlation value obtained for grain size and band gap is 0.9344 and 0.9136. Thus, concluded that grain size and bandgap of device is highly correlated.