Polarization Switching and Light-Enhanced Piezoelectricity in Lead Halide Perovskites

Abstract

We investigate the ferroelectric properties of photovoltaic methylammonium lead halide CH3NH3PbI3 perovskite using piezoelectric force microscopy (PFM) and macroscopic polarization methods. The electric polarization is clearly observed by amplitude and phase hysteresis loops. However, the polarization loop decreases as the frequency is lowered, persisting for a short time only, in the one second regime, indicating that CH3NH3PbI3 does not exhibit permanent polarization at room temperature. This result is confirmed by macroscopic polarization measurement based on a standard capacitive method. We have observed a strong increase of piezoelectric response under illumination, consistent with the previously reported giant photoinduced dielectric constant at low frequencies. We speculate that an intrinsic charge transfer photoinduced dipole in the perovskite cage may lie at the origin of this effect.

Ionic charging by local imbalance at interfaces in hybrid lead halide perovskites

“…In the configuration of the circuit in Figure 1(b), a voltage signal V app is applied to the sample C x across a reference linear capacitor C 0 (C x ( C 0 ) connected in series, thereupon the charge in C x (as in C 0 ) is Q ¼ C 0 V 0 , V 0 being the potential drop across the reference capacitor that is monitored with a high input impedance oscilloscope. Related experiments on CH 3 NH 3 PbI 3Àx Cl x based cells using ST circuit have shown in previous works 16, 21 the absence of ferroelectric behavior at room temperature. Alternatively to the ST circuit, dielectric responses are better checked by using other techniques as impedance spectroscopy for higher accuracy in the high-frequency (short time) range.…”

Effect of Internal Electric Fields on Charge Carrier Dynamics in a Ferroelectric Material for Solar Energy Conversion

“…[7][8][9] The organohalide lead perovskite materials currently yielding very promising photovoltaic device effi ciencies are also reported to be ferroelectric, although the importance of their ferroelectric properties in achieving such high effi ciencies is currently unclear. [10][11][12][13] In almost all cases where enhanced solar conversion performance has been attributed to ferroelectric materials properties, this enhancement has been assigned to reduced recombination losses. [ 11,14,15 ] However to date, to the best of our knowledge, there are no reports directly probing the extent to which spontaneous polarization can indeed increase charge carrier lifetimes.…”

Defect Dynamics in Proton Irradiated CH3NH3PbI3 Perovskite Solar Cells

“…high efficient solar cells [4,5] , photo-capacitors and piezoelectric sensors [6] , memristors [7] , etc.…”