Field effect and charge injection in hybrid nanorod heterostructure
- 作者：H.L. Kwok ; hlkwok@ece.uvic.ca ; Weicong Li
- 关键词：Charge injection ; Hybrid nanorod heterostructure ; Light emission ; Conduction mechanism ; Space-charge limited current ; Barrier height modification
- 刊名：Physica B
- 出版年：2012
- 期刊代码：53_09214526
- 类别：ph
- 出版时间：15 May, 2012
- 卷：407
- 期：10
- 页码：1513-1516
- 文件大小：218 K
摘要
Recent studies on organic/inorganic heterostructures have indicated that interface morphology plays an important role in determining the charge transport properties. Hybrid heterostructure light-emitting diodes mixing donor and acceptor semiconductors appear to offer the best opportunity in achieving superior performance and there are indications that a network of percolated heterojunctions can be very effective in promoting light absorption/emission. Charge transport however can be more complex in a nanorod heterostructure as the charge flow at the interface will depend on the injection mechanism(s) as well as the interface field strength. In this work, we examined the current density-voltage characteristics of the hybrid NPB (N, N鈥?di(napth-2-yl)-N-N鈥?diphenylbenzidine)-ZnO nanorod heterostructure and attempted to identify the transport mechanism(s) close to the tips of the nanorods. Our study indicated that charge flow essentially followed the conventional pattern changing from a linear regime (emission-limited) to a quadratic regime (space-charge limited) and possibly to a rapid rise in current (trap-free injection). Detailed evaluation of the changes in the reported conductivity data further suggested the conduction mechanism (up to a p-layer thickness of 400 nm) was dominated by space-charge limited current in the NPB layer, which also resulted in substantial charge pile-up near the tips of the nanorods. An interface charge layer responsible for the barrier height modification effect could be used to explain the observed 鈥渂lue-shift鈥?in the emission spectra of the nanorod heterostructure light-emitting diode as reported by Sun et al. .