Investigation on the Facet-Dependent Anisotropy in Halide Perovskite Single Crystals

Abstract

Metal halide perovskite (MHP) single crystals (SCs) are proven to possess superior optoelectronic properties compared to those of their polycrystalline thin film analogues. With the advancement and progress in the study of MHP SCs, it is found that the properties at the surface and bulk of SCs are significantly different. However, there are only a few studies present for the facet-dependent performance of MHP SCs. In this work, we have systematically investigated the anisotropic properties of naturally exposed facets (( 100) and ( 112)) in MAPbI 3 SCs. We studied the influence of temperature and illumination on the properties of these facets. It was found that hysteresis at the (112) facet is higher than that at the (100) facet because of the higher trap density of 1.17 × 10 13 cm −3 at this facet as compared to the trap density of 2.11 × 10 12 cm −3 for the (100) facet. Although there exist different kinds of defects at both the facets, the ion migration mechanism remains the same at both facets, which is confirmed by the obtained almost same activation energy of 0.378 and 0.308 eV for (100) and ( 112) facets, respectively, for ion migration. The photocurrent, responsivity, and EQE values further confirm anisotropic properties of both the facets in MAPbI 3 SCs although they are the same from the crystallography point of view. Thus, this study provides a detailed and systematic investigation of the facet-dependent properties in MHP SCs.

Electronic-Ionic Transport in MAPbBr3 Single Crystal: The Evidence of Super-Linear Power Law in AC Conductivity

“…The photocurrent increases with light intensity due to higher photocarrier generation at higher light intensities (Figure b). We have also calculated the responsivity ( R ) and detectivity ( D ) of the single-crystal detectors according to the following equations Here, I p is the photocurrent, I D is the dark current, S is the active area of the detector, and P j is the power of incident light …”

“…We have also calculated the responsivity (R) and detectivity (D) of the single-crystal detectors according to the following equations Here, I p is the photocurrent, I D is the dark current, S is the active area of the detector, and P j is the power of incident light. 39 The maximum values of R and D are 12.35 mA/W and 5.89 × 10 9 Jones, respectively. The corresponding EQE = hc/eλ (where h is the Planck constant, c is the speed of light, and λ is the wavelength of illuminated light) of these detectors is 38.8% at 5 V.…”

Role of Heterocyclic Organic Compounds on the Optoelectronic Properties of Halide Perovskite Single Crystals

“…This results in a relatively high defect density on the surface than on the bulk region . In view of this, the exact nature of traps and their effect on the optoelectronic properties are under active investigation. − Many efforts have been devoted to passivate the defects to increase the stability and performance of the halide perovskite SCs. To this end, one approach is to treat the crystals with various Lewis acid- or base-based ligands after synthesis ,, or to control the growth of SCs using additives. , Duim et al investigated the mechanism of surface passivation of methylammonium lead tribromide (MAPbBr 3 ) SCs using benzylamine, and it was reported that exposure to benzylamine results in the formation of two-dimensional (2D) (BA) 2 PbBr 4 on the surface of a three-dimensional (3D) perovskite by replacing the methylammonium cations .…”

Asymmetrical Electrical Performance across Different Planes of Solution-Grown MAPbBr3 Crystals of mm Dimensions

“…These discrepancies in the case of electronic and dielectric properties across various faces of the synthesized MAPbBr 3 crystals are due to structural defects, and these could be due to multiple types of defects. For example, density functional theories have been performed on various halide perovskite crystals to understand defects such as Frenkel defects due to the absence of Pb 2+ , I – , or MA + vacancies, and Schottky pair defects are due to PbBr 2 or MAI defects that do not generate trap states. − Since the current reaches the saturation domain for the more significant path along face III, contradicting the I–V nature across the crystals, we further investigated the correlations between electron transport and structural characterization across the various faces of our synthesized MAPbBr 3 crystals.…”