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.

Metal‐Free PAZE‐NH4X3⋅H2O Perovskite for Flexible Transparent X‐ray Detection and Imaging

“…The high temperature of weight loss suggests that the PAZE-NH 4 X 3 •H 2 O constructed with hydrogen bonds would be comparable to the traditional MHPs of MAPbI 3 (348 °C) and FAPbI 3 (363 °C) consisting of coordination bonds. [16][17][18][19][20][21][22][23][24][25][26][27] Then, scanning electron microscope (SEM) and energy-dispersive spectrometric (EDS) are further utilized to study their morphology properties and components difference in film. [12] The density functional theory (DFT) simulation is applied to explore the inherent properties of PAZE-NH 4 X 3 •H 2 O with different halide components.…”

“…[18] Subsequently, their photoelectric, ferroelectric and mechanical properties were systematically explored as well. [19][20][21] Recently, Cui et al firstly expanded them into X-ray detection, and studied the function of hydrogen bonds in the metal-free perovskites of DABCO-NH 4 X 3 with different halide anions. [12] It is found that hydrogen bonding influenced the charge transport mobilities, and the structural stiffness of metal-free perovskites because of the changed crystal packing behaviors, which drove molecular selfassembly to co-crystals.…”

A Review of Metal-Free Organic Halide Perovskite: Future Directions for the Next Generation of Solar Cells

“…(3) The phase boundary’s slope in the phase diagram is pivotal for the phase stability under transition. The MPB phase stability in a wider temperature span is provided by composition modulating . In order to design polar metal-free perovskite series, quasi-spherical and momentum matching theories should be exerted.…”

“…(c) Schematic illustration of the metal-free MDABCO-NH 4 X 3 perovskite. [Reproduced with permission from ref . Copyright 2022, Wiley–VCH.]…”

“…This widens the perovskite structure’s chemical versatility, rendering improved mechanical adaptability, lightweight, and cost-effective procedures. Despite all attainments, the basis of comprehension of the piezoelectric phenomenon in metal-free perovskites is still needed . In order to design polar metal-free perovskite series, quasi-spherical and momentum matching theories should be exerted.…”