Design Growth of Triangular Pyramid MAPbBr₃ Single Crystal and Its Photoelectric Anisotropy between (100) and (111) Facets

Abstract

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.

Fluorine‐Substituted Benzotriazole Core Building Block‐Based Highly Efficient Hole‐Transporting Materials for Mesoporous Perovskite Solar Cells

“…The typical PSCs usually possess a sandwich structure, including a fluorine‐doped tin oxide (FTO) layer, electron transport layer (ETL), perovskite absorber layer, hole transporting layer (HTL), and metal electrodes. The improved performance of PSCs relies on the optimization of perovskite composition, the design of outstanding charge collecting materials, and the device fabrication techniques . Specifically, hole transport material (HTM) is a key element for obtaining PSCs with excellent PCE and good stability.…”

Charge Transport Properties of Methylammonium Lead Trihalide Hybrid Perovskite Bulk Single Crystals

“…[ 47 ] Interestingly, work done by Jung et al has shown that at least for specially designed triangular pyramid MAPbBr 3 single crystals, the growth rate for each facet is anisotropic, in that the (111) facet grows faster than the (100) facet, due to the smaller interplanar distancing within the facet of 3.418 and 5.920 Ǻ, respectively. [ 51,52 ] So while, for the cubic‐shaped MAPbBr 3 , this will not have much of an impact, it will have a considerable impact on MAPbI 3 tetragonal crystals where each of the facets have differing interplanar distancing.…”

“…Also, to gain consistent reproducible results, a method such as vapor deposition of the electrodes is necessary, as this will deposit a thin uniform layer on the order of a hundred nanometers, of a gold or silver electrodes on the surface of the semiconductor, allowing for enough thickness for charge carriers to collect, while not thick enough for causing relatively large resistance. [ 52,79–81 ]…”

Perovskite Single Crystals: Synthesis, Optoelectronic Properties, and Application

“…Recently, Wei and co‐workers proposed a novel strategy to grow MAPbBr 3 SCs in dodecahedron shape with (110) facet naturally exposed rather than typical cuboid shape with (100) facet. Given the low bulk resistivity and large device noise of (111) facet of MAPbBr 3 SCs, [ 133 ] it is critical to compare the properties of (110) and (100) facets for high‐performance detectors. Surprisingly, the (110) facet has advantages in all properties, such as stronger PL intensity, longer carrier recombination lifetime, lower trap density, larger bulk resistivity and higher charge carrier mobility than that of (100) facets, as well as one order of magnitude larger μτ product of 0.0259 cm 2 V −1 .…”