Lead halide perovskite materials, such as MAPbBr 3 and MAPbI 3 , 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 (E bi ) of the depletion region with piezoelectricity at the Au/MAPbBr 3 interface. As a result, the photovoltaic short-circuit current density (J sc ) and the open-circuit voltage (V oc ) are increased by 670 and 82%, respectively, by applying an external strain upon an asymmetric solarcell-like Au/MAPbBr 3 /Ga structure. Furthermore, the equivalent piezoelectric d 33 values of ∼3.5 pC/N are confirmed in the Au/MAPbBr 3 /Au structure with both the sinusoidal strain and the 405 nm light illumination with 220 mW/cm 2 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.

MAPbI3, MAPbBr3, and CsPbBr3 are excellent halide perovskite semiconductors with super long carrier diffusion length, long minority carrier lifetime, and large light absorption coefficient. Compared with the small intrinsic electrostriction, photocarriers induce a large photostriction in the surface layer. Furthermore, an electric field can efficiently separate the light excited electron–hole pairs, enhance photocarriers diffusion, and finally increase the crystal expansion, i.e., photo-electro-striction. For each crystal under 30 V/mm and in light with 450 nm wavelength and 840 mW/cm2, the photo-electro-striction is over four times of the pure electrostriction and is larger than the sum of photostriction and electrostriction. Most importantly, MAPbI3 single crystal shows a large photostriction of ∼0.35% and the photo-electro-striction of ∼0.64%. This work proves a very large photo-electro-striction as a result of the strong coupling among photocarriers, electric fields, and crystal lattices, which is important to develop semiconductor devices.

Flexible devices have aroused great interest due to their potential for wearable and portable applications. In this paper, the [001]-oriented all-inorganic perovskite CsPbBr3 films were grown on a flexible polyimide substrate, and the corresponding flexible self-powered photodetectors (PDs) were prepared. The [001]-oriented CsPbBr3 films have an atomically flat surface and a low defect density. Under zero bias voltage and 405 nm irradiation, the flexible PD presents a responsivity of 151.9 mA W–1 and a specific detectivity of 1.895 × 1013 Jones under a light intensity of 2 μW cm–2 and a photocurrent on/off ratio of 4.54 × 106 under a light intensity of 165 mW cm–2. The CsPbBr3 PDs can work without an external power supply and are typical self-powered detectors. In addition, the detector still exhibits excellent flexibility and electrical stability after the repeated bending with the 4 mm radius. This study is expected to promote the commercial application of large-area flexible perovskite-based photoelectronic devices.

CsPbBr3 shows excellent photoelectric properties such as a direct bandgap of 2.25 eV, large optical absorption coefficient, and strong luminescence intensity. Therefore, it is promising to be applied in LED devices. It is important to modulate and enhance photoluminescence (PL) intensity through external stimulus. Here, (001) CsPbBr3 films with nanocrystals were grown on the PMN-PT ferroelectric single crystal substrate, and its PL can be largely modulated by the ferroelectric polarization switching of PMN-PT. The saturated polarization of a 90 nm thick CsPbBr3 film induces a 67% increase in the PL intensity, which is due to piezoelectric strain passivated defects, resulting in decreased nonradiative recombination. However, the upward saturated polarization of the 40 nm thick CsPbBr3 film introduces a 55% decrease in the PL intensity, which can be attributed to the inner electric field separating the light-excited electron–hole pairs, thereby decreasing their radiative combination. This reversible and tunable photoluminescence is important for the development of advanced multifunctional optoelectrical devices.