Large-scale cubic and triangular prism MAPbCl3 single crystals with (100) and (110) planes were grown, and the optoelectronic anisotropy of MAPbCl3 was revealed.

MAPbI is deemed as the most prominent member in hybrid perovskites family because of its extremely optoelectronic properties. However, some issues and puzzles are still in expectation of their answers, such as stabilities, hysteresis, ferroelectricity, and so on. To bridge the distinctions between MAPbI single crystal and thin films, large-size single crystals are demanded. On the contrary, crystal structure anisotropy-dependent optoelectronic properties is an inevitable topic. A series of large-size MAPbI single crystals with (220) facets exposed were successfully grown, using high concentration solutions and large-size seed crystals to match growth rates of (100) and (220) facets. The optoelectronic properties of photocurrents, responsivity, EQE, and detectivity clearly showed significant anisotropy of optoelectronic properties in MAPbI single crystal. According to ion migration theory, the anisotropy of optoelectronic properties was interpreted. We hope this result will be helpful to guide oriented growth MAPbI thin films.

Centimeter-size 2D layered Pb-free (CH3NH3)2MnCl4 single crystal was grown by using different ways and proved to have good luminous via fabricating LED device.

CH3NH3PbBr3 (MAPbBr3), one of the classical members in the organic–inorganic hybrid perovskite family that presents excellent advantages in high photon absorption efficiency and long carrier transport distance, is expected to break the record in responsiveness and efficiency as a photodetector, because single crystal is superior to its thin films, nanowires, and other counterparts. Moreover, single crystal provides adequate media to reveal the intrinsic photoelectric properties, such as defect-related dark current, mixed-ionic conductivities, etc. The mixed-ionic conductivities in MAPbBr3 single crystal are considered to be associated with the atomic packing densities, which are deemed as crystalline oriented or anisotropic. In this study, a series of large-sized MAPbBr3 single crystals with (100) and (111) facets exposed were successfully grown through a crystal-limiting method. By fabricating metal–semiconductor–metal planner photodetectors on both (100) and (111) facets with Au interdigital electrodes in only a MAPbBr3 single crystal, the photoelectric anisotropy was systematically compared in terms of ion migration and the anisotropy of current and on–off ratios. This reveals that the higher MA+ and [PbBr6]4– densities in (111) plane cause a higher built-in electric field, which ultimately affects the dark current, photocurrents, and on–off ratios.

Hybrid organic-inorganic lead halide perovskites (HOIPs) have received significant attention because of their impressive performances in the fields of solar cells and photoelectric detection. In the past five years, great efforts have been made to improve the crystallinity, reduce grain boundaries, and enhance the stabilities of perovskite films. Compared with films, HOIP single crystals possess fewer grain boundaries and stronger optoelectronic properties and can be applied in optoelectronic devices. As the most popular HOIP member, single crystals of MAPbX (X = Br, Cl) are deemed as important candidates for ultraviolet-visible photodetectors, in which the crystal structure anisotropy largely affects the detection performance. In this study, high-quality cubic single crystals of MAPbBr and MAPbCl were successfully grown from solutions. Taking advantages of their smooth (100) facets, planar metal-semiconductor-metal photodetectors were fabricated using Au interdigitated electrodes. The optoelectronic performances under nonpolarized and linearly polarized lights were explored. The optoelectronic performances were dependent on linearly polarized lights. Interestingly, both responsivity and external quantum efficiency were greatly enhanced under the excitation with linearly polarized lights. Moreover, the polarization-related optical absorptions and the electron densities within the (100) plane could be used to interpret different optoelectronic performances of single crystals of MAPbX (X = Br, Cl) under various linearly polarized lights.