Analysis of carrier behavior in C60/P(VDF-TrFE) double-layer capacitor by using electric-field-induced optical second-harmonic generation measurement

Abstract

By using displacement current measurement (DCM) and electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the carrier behavior in the indium-tin oxide (ITO)/Poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/C60/Au(or Al) capacitors. Two DCM peaks appeared asymmetrically at around −35.5 V and +30.0 V in the dark. Correspondingly, the EFISHG response from the C60 layer was observed, but the peak positions were different with respect to DCM ones. The results show that the spontaneous polarization of the ferroelectric P(VDF-TrFE) polymeric layer directly affects the electric field in the C60 layer, and thus governs the carrier motion in this layer. As a result, the C60 layer serves like an insulator in the dark, while electrons and holes are captured and released at the interface in response to the turn-over of spontaneous polarization of ferroelectric layer. On the other hand, under white light illumination, C60 layer serves like a conductor due to the increase of photogenerated mobile carriers, and these carriers dominate the carrier motions therein. Our findings here will be helpful for analyzing carrier behaviors in organic electronic devices using ferroelectric polymers.

A way for studying the impact of PEDOT:PSS interface layer on carrier transport in PCDTBT:PC71BM bulk hetero junction solar cells by electric field induced optical second harmonic generation measurement

“…As a result, the SH intensity in the BHJ layer is generated in proportion to jE b þ E e (t)j 2 , where E e (t) ¼ (V ex /d)(1-exp(-t/t RC )). [7][8][9]12 Here, d is the thickness of BHJ layer, and t RC is the circuit response time that can be given by t RC ¼ RC (R is the series The decrease or increase in the electric field in the BHJ layer depends on the polarity of the "E b ". Results given in Figure 5(a) show that the electric fields "E b1 " in PCDTBT and "E b2 " in PC 71 BM are pointing in the direction from ITO to Al electrode.…”

“…Here,Ẽ b is formed due to work function difference of the electrodes, whereasẼ ext andẼ sc are mainly formed under voltage application. [7][8][9] In the presence of local electric field Eð0Þ, the EFISHG is activated. During the EFISHG measurements, we used red light (660 nm wavelength, 10 Hz repetition, 50 ms duration) emitted from a laser diode to induce photo current.…”

Modeling and visualization of carrier motion in organic films by optical second harmonic generation and Maxwell-displacement current

“…These studies are mainly carried out by means of electrical measurements such as displacement current measurement (DCM) using ramp voltage [150,151], but these are no longer sufficient to account for carrier behaviors in a variety of organic semiconductor devices being utilized with ferroelectric P(VDF-TrFE) layers. Using EFISHG probes the electric field change induced in organic devices with a ferro-electric layer gives much information on the carrier behavior in these devices [152][153][154]. Figure 16 shows a typical example of DCM measurements for MFM and MFSM (the inset of Fig.…”

“…layers. Using the EFISHG measurement is an effective way for clarifying the contribution of organic semiconductor layers [153,155].…”

Direct visualization of polarization reversal of organic ferroelectric memory transistor by using charge modulated reflectance imaging

“…In our previous paper, we studied the displacement current-voltage characteristics of metal/ ferroelectric/ organic semiconductor/ metal (MFS) diodes by using the EFISHG measurement [26]. Results showed that the EFISHG measurement coupled with displacement current measurement (DCM) is useful for analyzing the relationship between the polarization reversal process in the ferroelectric layer and associated carrier behaviors in the semiconductor layer, in terms of the three-peak generation in the DCM [27][28][29]. We also used the charge modulation spectroscopy (CMS) to study the relationship between the related energetics of carriers in semiconductor layer and polarization reversal in MFS diodes [26].…”