Optical and electronic properties in new conducting polymer and interfacial electronic phenomena

Optical properties and electronic structure of new fusible and soluble conducting polymer based on poly(p-phenylene), poly(1,4-bis(2-thienyl)-2,5-dialkoxyphenylene) ROPBTP, and poly(2,5-dialkoxy-1,4-phenylene-alt-2,5-thiophene), ROPPT, are investigated. Thermochromic behavior observed in ROPBTP and ROPPT is a little different from poly(3-alkylthiophene) (P3AT), which are discussed by taking differences in molecular structures into account. The interfacial electronic energy diagrams of conducting polymer/metal interfaces were evaluated by the photoelectron spectroscopy. The shifts of the vacuum level were observed at all the measured interfaces and could be expressed as a linear relationship of work function of the metal, showing the formation of an interfacial electric dipole layer. For good understanding the properties of the organic electronic devices such as electroluminescent devices and organic photovoltaic cells, it is extremely important to directly clarify the interfacial electronic structures by non-contact technique such as photoemission spectroscopy.