Prospects of Metal-Free Perovskites for Piezoelectric Applications

Abstract

Metal-halide perovskites have emerged as versatile materials for various electronic and optoelectronic devices such as diodes, solar cells, photodetectors, and sensors due to their interesting properties of high absorption coefficient in the visible regime, tunable bandgap, and high power conversion efficiency. Recently, metal-free organic perovskites have also emerged as a particular class of perovskites materials for piezoelectric applications. This broadens the chemical variety of perovskite structures with good mechanical adaptability, light-weight, and low-cost processability. Despite these achievements, the fundamental understanding of the underlying phenomenon of piezoelectricity in metal-free perovskites is still lacking. Therefore, this perspective emphasizes the overview of piezoelectric properties of metal-halide, metal-free perovskites, and their recent progress which may encourage material designs to enhance their applicability towards practical applications. Finally, challenges and outlooks of piezoelectric metal-free perovskites are highlighted for their future developments.

Keywords: metal-free perovskites; piezoelectric devices; piezotronics; symmetry breaking.

Figure 1

Schematic of the halide perovskite structure.

Figure 2

The schematic representation of the metal‐free MDABCO‐NH₄X₃ perovskite.

Figure 3

a) Modification of molecular symmetry. b) Initial structural phase transition. c) Modified phase transition. Reproduced with permission.^{[ 32 ]} Copyright 2019, American Chemical Society.

Figure 4

a) The calculated piezoelectric strain tensor of MDABCO‐NH₄X₃. b) The calculated elastic compliance tensor of MDABCO‐NH₄X_3. Reproduced under terms of Creative Commons Attribution 4.0 International license.^{[ 57 ]} Copyright 2019, The Authors, published by Springer Nature.

Figure 5

a) Schematic of a biodegradable piezoelectric Poly‐L‐lactic acid (PLLA) sensor. b) Distinct force signal produced by PLLA sensor when the mouse was alive and under anesthesia (black), and when the mouse was euthanized by an overdose of anesthetics (red). Reproduced with permission.^{[ 87 ]} Copyright 2018, National Academy of Sciences. c) Schematic of fiber optic and PVDF pressure sensors inserted into the round window of a gerbil cochlea. d) Output voltage measured with PVDF sensor (red) and pressure in the scala tympani measured with fiber optic sensor (black). e) Phase measured with fiber optic pressure sensor (black circle), PVDF sensor pre‐mortem and before disarticulation (red squares), postmortem (blue triangles), and after disarticulation (greed diamonds). f) Output voltage measured with PVDF sensor pre‐mortem or before disarticulation (red squares), postmortem (blue triangles), and after disarticulation (green diamonds). Reproduced under terms of Creative Commons Attribution 4.0 International license.^{[ 116 ]} Copyright 2018, The Authors, published by SAGE. g) Illustration of PVDF‐based actuators and tissue stimulators of the cell culture exposed to micro‐vibration. Reproduced with permission.^{[ 126 ]} Copyright 2010, Elsevier.

Figure 6

a) Device schematic of a CsPbBr₃ nanogenerator and self‐powered physiological signal characterizations from b) coughing/yawning. Reproduced with permission.^{[ 129 ]} Copyright 2020, Royal Society of Chemistry. Output of the real‐time sensor in terms of waveforms measured from c) wrist, d) neck e) arm, and f) drinking movements. Reproduced with permission.^{[ 130 ]} Copyright 2020, American Chemical Society. Schematics of g) aligned M13 bacteriophage nanopillars and h) the piezoelectric dipole on vertical direction. Reproduced with permission.^{[ 21 ]} Copyright 2015, Royal Society of Chemistry.

Figure 7

a) A SnO₂/PVDF PENG with self‐cleaning ability. Reproduced with permission.^{[ 134 ]} Copyright 2019, Elsevier. Schematic representation of b) self‐powered integrated wireless electronic node (SIWEN) applications in hybrid perovskite‐based nanocomposites and c) signal transmission by cellphones. d) Charging a 1 µF capacitor by a single perovskite/polymer PENG while exciting by an automobile engine and e) engine vibration detection scene. Reproduced with permission.^{[ 138 ]} Copyright 2020, Royal Society of Chemistry.

Figure 8

a) Principles of piezotronics in a nanowire (up) and a field‐effect transistor (bottom). Reproduced with permission.^{[ 139 ]} Copyright 2007, Wiley‐VCH. b) Strain‐gated ZnO nanowire Schottky diode. Reproduced with permission.^{[ 140 ]} Copyright 2007, Wiley‐VCH. c) Strain‐gated field‐effect transistor. Reproduced with permission.^{[ 141 ]} Copyright 2017, Wiley‐VCH. d) Piezotronic effect‐enhanced perovskite solar cell. Reproduced with permission.^{[ 143 ]} Copyright 2019, American Chemical Society. e) Metal‐insulator‐semiconductor structured photodetector based on ZnO nanorods. Reproduced with permission.^{[ 142 ]} Copyright 2014, Elsevier. f) Piezotronic effect‐enhanced organic light‐emitting diode. g) Piezopotential distribution in a ZnO nanowire and enhanced current and light emission of the device. Reproduced with permission.^{[ 144 ]} Copyright 2017, American Chemical Society.