Ferroelectric materials, which exhibit switchable polarization, are potential candidates for photovoltaic applications owing to their intriguing charge carrier separation mechanism associated with polarization and breaking of inversion symmetry. To overcome the low photocurrent of ferroelectrics, extensive efforts have focused on reducing their bandgaps to increase the optical absorption of the solar spectrum and thus the power conversion efficiency. Here, a new avenue of enhancing photovoltaic performance via engineering the polarization across a morphotropic phase boundary (MPB) is reported. Tetragonal compositions in the vicinity of the MPB in a PbTiO3‐Bi(Ni1/2Ti1/2)O3solid solution are shown to generate up to 3.6 kV cm−1photoinduced electric field and 6.2 µA cm−2short‐circuit photocurrent, multiple times higher than its pseudocubic counterpart under the same illumination conditions with excellent polarization retention. This enhancement allows the investigation of the correlation between the polarization switching and photovoltaic switching, which enables a controllable multistate photocurrent. Combined with a bandgap of 2.2 eV, this material exhibits a sizable photoresponse over a broad spectral range. These findings provide a new approach to improve the photovoltaic performance of ferroelectric materials and can expand their potential applications in optoelectronic devices.
Ferroelectric materials exhibit coupled degrees of freedom and possess a switchable electric polarization coupled to strain, making them good piezoelectrics and enabling numerous devices including nonvolatile memories, actuators, and sensors. Moreover, novel photovoltaic effects are encountered through the interplay of electric polarization with the material optical properties. Consequently, light‐induced deformation in ferroelectrics, or photostriction, combining photovoltaic and converse piezoelectric effects, is under investigation in the quest for multifunctional materials. Using time‐resolved X‐ray diffraction, the first control of ultrafast photoinduced strain is demonstrated through in situ tuning of the polarization state in ferroelectric‐based devices. Both the magnitude and the sign of the photoinduced strain strongly depend on the transient photoinduced change of the internal electric field in the ferroelectric layer, and can be actively engineered to achieve two distinct remanent photostrictive responses. These results provide fundamental insight into light–matter interaction in ferroelectrics and exciting new avenues for materials functionality engineering.
more » « less- NSF-PAR ID:
- 10461209
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 5
- Issue:
- 6
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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