Low band gap conformal polyselenophene thin films by oxidative chemical vapor deposition

Abstract

Low band gap conjugated polymers are attractive for their applications in many devices including field-effect transistors, light-emitting diodes, electrochromic devices and photovoltaics. Selenophene-based polymers have many advantageous properties over polythiophene. However, poor solubility of solution-synthesized polyselenophene restricts its applications in the form of thin films. Electrochemical deposition of polyselenophene thin films is possible, but this process is limited to conductive substrates only. In this work, for the first time, we report deposition of polyselenophene (pSe) thin films on non-conductive substrates by a vapor based method, known as oxidative chemical vapor deposition (oCVD). oCVD synthesized pSe thin films were characterized by FT-IR, UV-Vis and X-ray photoelectron spectroscopies. Moreover, the oCVD made pSe shows 0.14 eV lower band gap than its calculated values. Vapor phase deposition of pSe by oCVD provides conformal thin films in a single and dry step. The conformal and dry nature of the pSe film deposition by oCVD may be employed for fabrication of devices on paper based substrates.