Junction properties of Schottky diode with chemically prepared copolymer having hexylthiophene and cyclohexylthiophene units

A Schottky diode has been constructed from chemically synthesised copolymer of cyclohexyl and hexyl substituted thiophene units, and various metals such as In, Ag, Al, Sn, etc. The polymer film was deposited on SnO2 coated glass substrate using spin casting technique. The electrical properties of the diode have been investigated by current–voltage and capacitance–voltage measurements. These characteristics were compared with those of poly(3-cyclohexylthiophene) (P3cHT) and poly(3-n-hexylthiophene) (P3nHT) based diode. Junction parameters, such as, ideality factor (n) and barrier height (χ) have been calculated by applying thermionic emission theory. The values of n and χ for copolymer/metal junctions were found to be in between the corresponding values for P3cHT/metal and P3nHT/metal junctions. Poor performance of the copolymer/metal diode, compared to P3cHT was attributed to the steric effects produced by hexyl substituents present in the copolymer.