A prerequisite to achieving high performance polymer/inorganic thin film diodes

An alternative approach to high performance polymeric rectifiers based on p-type polymer poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and an n-type zinc oxide (ZnO) films is demonstrated. It is evident that nanoscale grain compatibility at an interface does not ensure that the device has the highest performance, but only a prerequisite for the two materials to exhibit the interaction. Being a non-invasive probe, Raman spectroscopy is used to monitor the degree of interaction between PEDOT:PSS and ZnO films. High performance of devices is achieved by the control of grain matching and more essentially, by the strong interaction of molecules at the interface. The developed PEDOT:PSS/ZnO diode can rectify an incoming a.c. voltage signal at frequencies up to 18 MHz. Operating with a low turn-on voltage, the diode has a current density of 220 mA/cm2 and a rectification ratio of 4000 in the open atmosphere which are higher than previously reported polymer/inorganic vertical diodes.