Polarization Switching and Light-Enhanced Piezoelectricity in Lead Halide Perovskites.
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.
†Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193, Bellaterra, Catalonia, Spain.
Mariona
M
Coll
†Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193, Bellaterra, Catalonia, Spain.
Andrés
A
Gomez
‡Photovoltaics and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, 12071, Castelló, Spain.
Elena
E
Mas-Marza
‡Photovoltaics and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, 12071, Castelló, Spain.
Osbel
O
Almora
‡Photovoltaics and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, 12071, Castelló, Spain.
Germà
G
Garcia-Belmonte
†Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193, Bellaterra, Catalonia, Spain.
Mariano
M
Campoy-Quiles
‡Photovoltaics and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, 12071, Castelló, Spain.|§Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 22254, Saudi Arabia.
Juan
J
Bisquert
CH3NH3PbI3; dipole; dipole moment; ferroelectric; hysteresis; loops; perovskite solar cells; piezoelectric force microscopy; polarization