Macroscopic Piezoelectricity of Halide Perovskite Single Crystals and Their Highly Sensitive Self-Powered X-ray Detectors.

The FAxMA1-xPbI3 single crystal has excellent semiconductor photoelectric performance and good stability; however, there have been conflicting opinions regarding its macroscopic piezoelectricity. Here, the FAxMA1-xPbI3 (x = 0-0.1) single crystals (FAx SCs) exhibit a high macroscopic piezoelectric d33 coefficient of over 10 pC/N. The single crystal transforms from a tetragonal ferroelectric phase to a cubic paraelectric phase at x = 0.1-0.125. Furthermore, the fully polarized MAPbI3 and FA0.05 SCs were applied to prepare self-powered X-ray detectors with vertical structures. The sensitivity of the detector reaches 5.1 × 104 µC·Gy-1·cm-2 under a 0 V bias voltage, and its detection limit is as low as 50 nGy/s. This work provides an approach to designing self-powered and high-quality detectors with piezoelectric semiconductors.

Strain-Manipulated Photovoltaic and Photoelectric Effects of the MAPbBr3 Single Crystal.

Lead halide perovskite materials, such as MAPbBr3 and MAPbI3, show excellent semiconductor properties, and thus, they have attracted a lot of attention for applications in solar cells, photodetectors, etc. Here, a periodic strain can dynamically manipulate the build-in electric field (Ebi) of the depletion region with piezoelectricity at the Au/MAPbBr3 interface. As a result, the photovoltaic short-circuit current density (Jsc) and the open-circuit voltage (Voc) are increased by 670 and 82%, respectively, by applying an external strain upon an asymmetric solar-cell-like Au/MAPbBr3/Ga structure. Furthermore, the equivalent piezoelectric d33 values of ∼3.5 pC/N are confirmed in the Au/MAPbBr3/Au structure with both the sinusoidal strain and the 405 nm light illumination with 220 mW/cm2 upon one semitransparent Au electrode. This study not only proves that pressure can effectively enhance the energy conversion efficiency of the halide perovskite-based solar cells and light detectors but also supposes a multifunctional sensor, which can detect light intensity, sense dynamic pressure, explore accelerated speed, etc. simultaneously.