Study of effect of inserted pentacene layer in ITO/P(VDF-TrFE)/α-NPD/Au capacitor using electric-field-induced optical second-harmonic generation and displacement current

The effect of inserted pentacene layers on the interface optimization was investigated in the indium- tin oxide (ITO)/Poly(vinylidene fluoride-trifluoroethylene) (P(VDF- TrFE))/N,N'-bis(1-naphthyl)-N,N'-diphenyl-1, 1'-biphenyl-4,4'-diamine (alpha-NPD)/Au capacitors, by using displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement. Results show that the inserted pentacene layer between the alpha-NPD and P(VDF-TrFE) layers effectively improves the contact between the semiconductor and the ferroelectric P(VDF-TrFE) and it further enhances dipolar switching, resulting in three peaks in the DCM, while the insertion of a pentacene layer between the alpha-NPD and the Au electrode can effectively acquire holes from the Au electrode to be conductive, only leading to peak shift in the DCM with only two peaks. It is concluded that pentacene is a good candidate available for the interface optimization of organic devices. (C) 2013 Elsevier B.V. All rights reserved.