The influence of dipoles orientation on the charge transport mechanism of Au/rr-P3HT/P(VDF-TrFE) heterojunction diode in the form of 1D-line grating nanostructure arrays

Abstract

One dimension line grating nanostructure arrays of organic ferroelectric/semiconductor (P3HT/PVDF-TrFE) hetero-junction was developed via nanoimprinted lithography technique. The nanoimprinted ferroelectric heterojunction showed excellent piezoelectric and ferroelectric properties. The influence of dipoles orientation on the I-V characteristics of the developed nanoimprinted heterojunction was examined. The state of polarization showed a band bending of the HOMO and LUMO levels of the P3HT. This band bending lowered the barrier between the P3HT semiconductor and the Au electrode when the P(VDF-TrFE) was negatively poled. The charge conduction mechanism of the developed nanoimprinted heterojunction was investigated by mean of Schottky model. It was found that the state of polarization affects the barrier height and caused a modulation of the band offset. This modulation was confirmed by the photoelectron emission and inverse photoemission spectroscopies measurement. The change of state of polarization from positive to negative poling caused a clear shift in the valence band toward the Fermi level by 2.1 eV and shifted the conduction band toward the Fermi level by 0.4 eV. Moreover, The band gap of the developed organic heterojunction is decreased by 2.5 eV when the state of polarization of the ferroelectric P(VDF-TrFE) is changed from positive to negative poling.