Effect of thermal annealing on ferroelectric domain structures in poly(vinylidene-fluoride-trifluorethylene) Langmuir-Blodgett thin films

Abstract

Xia, "Effect of thermal annealing on ferroelectric domain structures in poly(vinylidene-fluoride-trifluorethylene) Langmuir-Blodgett thin films" (2014 We report a piezo-response force microscopy study of the effect of thermal annealing on ferroelectric domain structures in 6 to 20 monolayer (11 to 36 nm) polycrystalline poly(vinylidene-fluoridetrifluorethylene) thin films prepared using the Langmuir-Blodgett approach. Stripe-shape domains have been created at room temperature and subjected to thermal annealing at progressively higher temperatures up to the ferroelectric Curie temperature T C of approximately 110 C. The static configuration of the domain walls exhibits no appreciable temperature dependence after thermal annealing, with the domain-wall roughness exponent f ranging from 0.4 to 0.5. Above 80 C, we observed spontaneous polarization reversal at randomly scattered local sites in both polarization states. The number of domain nucleation centers increases rapidly as a function of temperature. We compared the thermally driven domain formation in ferroelectric polymers with those observed in ferroelectric oxides and attributed the difference to the distinct mechanisms for domain formation in these two systems. V C 2014 AIP Publishing LLC. [http://dx

Enhanced Piezoelectric Response in Hybrid Lead Halide Perovskite Thin Films via Interfacing with Ferroelectric PbZr0.2Ti0.8O3

“…Such fluctuations in the PFM response may originate from the variation of the polar axis within a crystalline grain, pointing to a relatively low DW energy. 36 This is consistent with the polar liquid scenario for the molecular dipole reorientations, 37 where the electrostatic and elastic energy of the DW can be minimized through dielectric screening and local polaron formation. On the 300 nm MAPbI 3 film deposited on PZT, on the other hand, the PFM image exhibits a qualitatively different phase landscape with much larger variation (Figure 1d).…”

“…1(b)). This points to the existence of polar domains within a grain, suggesting that the DW energy in MAPbI 3 is relatively low [30]. The high phase angle also suggests that the polar axis for samples on PZT is close to the surface normal.…”

“…Once the domains with P up and P down states are seeded, it is energetically unfavorable for the growth of domains with other polar axis, as it requires the formation of charged DW. The long-range dipole interaction is known to be an important energy scale in ferroelectric materials that competes with the elastic energy in determining the DW energy and domain structures in epitaxial PbZr 0.2 Ti 0.8 O 3 thin films[37] and layered ferroelectric copolymer poly(vinylidene-fluoride-trifluorethylene) [P(VDF-TrFE)][30,38].…”

Ferroelectric-Domain-Patterning-Controlled Schottky Junction State in Monolayer MoS2

“…Rather, the conduction has to be modeled as a Schottky junction in series connection with a resistor [31]: As a control experiment, we erased the domain structure by thermally heating the sample in vacuum to 80 °C, close to its Curie temperature, for 2 hours. The copolymer film then recovers its as-deposited state with polarization randomly orientated, which can be attributed to its low DW energy [38]. After thermal depolarization, the I DS -V DS curve at V BG = -10 V agrees well with the linear behavior in the as-deposited state (Fig.…”

“…1(a)), where the copolymer film was deposited using the Langmuir-Blodgett (LB) technique [29][30][31]. Unlike the thick P(VDF-TrFE) films prepared by spin-coating [17,18,22,26], the ultrathin LB films possess smooth surfaces (~1 nm surface roughness) and low coercive voltage (< 10 V), making it possible to write and image ferroelectric domains with nanoscale precision via the conductive probe atomic force microscopy (AFM) and piezo-response force microscopy (PFM) [37,38]. The reported electrical results were based on 6 MoS 2 samples, denoted as D1-D6.…”