The rectifying characteristics of the electropolymerized ultro-thin films of thiophene and thiophene derivatives

Summary form only given. The conjugated organic ultra-thin films of 2,2-bithiophene(PT), 3-methythio-phene (PMT) and 3-bromothiophene (PBrT) are prepared dy electrochemical polymerization. The electrochemical properties of the single layer films well studied. And the absorption spectra of the films in reduction and oxidation conditions were measured respectively. The data of thermo-emf confirmed that the film of PBrT is p-type behaviore, while the films of PT and PMT exhibited the feature of weak donor. The single-layer and bilayer film cells, with ITO/polymer/Au and ITO/polymer1/polymer2/Au sandwich structure, were composed of PT, PMT and PBrT. No distinct reatifying behaviore was observed all of the single-layer film cells. This fact suggests that there should be no any juction or Schottky berrier between ITO and polymer or Au and polymer interface. The bilayer film cells, e.g. ITO/PBrT/PMT/Au and ITO/PBrT/ PT/Au, show excellent rectifying ability similar to a p-n junction diode and some extent of photo-electric conversion. The rectifying ratio reach about 200. However, the cells of ITO/PT/PBrT/Au and ITO/PMT/PBrT did not show rectifying characteristic. The phenomenon should be attributed to the overoxidation during electropolymerization.