The study of the open-circuit thermally stimulated discharge on the guest-host nonlinear optical polymer electret DR1/PMMA film

In this paper the charge dynamic characteristic of the guest-host NLO polymer electret DR1/PMMA films after corona poling is investigated by means of the thermally stimulated discharge (TSD) technology. The results indicate that in the sample poled by the constant voltage corona charging near the glass transition temperature (Tg) there are two kinds of charges: space charge trapped by the traps of sample and dipole charge originating from the oriented dipole, and the dipole charge is completely compensated by the space charge. Most of trap energy levels of the space charges are higher than the bound levels of dipole charges at the suitable poling temperature. The breadth B of site distribution in the KWW stretched exponential expression applied to fit the relaxation of the oriented dipole is correlated to the interaction between dipole and space charge. Aging can lead to the space charge transferring to deeper traps due to the fast retrapping effect, which makes the space charge more stable, and consequently improves the orientation stability of the dipole and optical nonlinear stability.