Distinct Carrier Transport Properties Across Horizontally vs Vertically Oriented Heterostructures of 2D/3D Perovskites

Abstract

Two-dimensional-on-three-dimensional (2D/3D) halide perovskite heterostructures have been extensively utilized in optoelectronic devices. However, the labile nature of halide perovskites makes it difficult to form such heterostructures with well-defined compositions, orientations, and interfaces, which inhibits understanding of the carrier transfer properties across these heterostructures. Here, we report solution growth of both horizontally and vertically aligned 2D perovskite (PEA)2PbBr4 (PEA = phenylethylammonium) microplates onto 3D CsPbBr3 single crystal thin films, with well-defined heterojunctions. Time-resolved photoluminescence (TRPL) transients of the heterostructures exhibit the monomolecular and bimolecular dynamics expected from exciton annihilation, dissociation, and recombination, as well as evidence for carrier transfer in these heterostructures. Two kinetic models based on Type-I and Type-II band alignments at the interface of horizontal 2D/3D heterostructures are applied to reveal a shift in balance between carrier transfer and recombination: Type-I band alignment better describes the behaviors of heterostructures with thin 2D perovskite microplates but Type-II band alignment better describes those with thick 2D microplates (>150 nm). TRPL of vertically aligned 2D microplates is dominated by directly excited PL and is independent of the height above the 3D film. Electrical measurements reveal current rectification behaviors in both heterostructures with vertical heterostructures showing better electrical transport. As the first systematic study on comparing models of 2D/3D perovskite heterostructures with controlled orientations and compositions, this work provides insights on the charge transfer mechanisms in these perovskite heterostructures and guidelines for designing better optoelectronic devices.

Design of two-dimensional halide perovskite composites for optoelectronic applications and beyond

“…Zhao et al 38 fabricated a 2D/3D perovskite composite by adding Cs + to 2D (PEA) 2 PbBr 4 nanoplate, which combined the excellent stability of 2D perovskites and low exciton binding energy of 3D perovskites and was promising for practical LEDs. Wright et al 39 reported the heterostructure of both horizontally and vertically aligned perovskite (PEA) 2 PbBr 4 grown on 3D CsPbBr 3 in solution, which provided an ideal platform to study the physical properties and cross-heterojunction charge transfer process in a more explicit 37 ; (e). Morphology of perovskite thin films (The scale bar is 10 μm.).…”

Formamidinium-based Ruddlesden–Popper perovskite films fabricated via two-step sequential deposition: quantum well formation, physical properties and film-based solar cells

“…Previous studies have shown that the n = 1 phase tends to be aligned parallel to the substrate and is unfavorable for carrier transport in the device. 48 This peculiarity may indicate efficient charge transport in these three films. A key merit of the PMAI : FAI ratio in precursors is that a higher FAI ratio leads to the transformation of dominant layered perovskites from PMA 2 FA nÀ1 Pb n I 3n+1 to FA 2 FA nÀ1 Pb n I 3n+1 .…”

Hydration Intermediate Phase Regulated In‐Plane and Out‐Plane Epitaxy Growth of Oriented Nano‐Array Structures on Perovskite Single Crystals

“…[21] Besides, Wright et al fabricated a horizontally versus vertically oriented heterostructures of 2D/3D perovskites and carrier transport properties were studied in detail. [22] Xu et al developed a highly controllable homoepitaxial growth method of hybrid perovskites for LED arrays. [23] The dry and wet etching and vapor deposition process could result in accurately controlled and highly ordered patterned structures, but these arrays growth always required complex fabrication process and equipment when scale up fabrication.…”

“…fabricated a horizontally versus vertically oriented heterostructures of 2D/3D perovskites and carrier transport properties were studied in detail. [ 22 ] Xu et al. developed a highly controllable homoepitaxial growth method of hybrid perovskites for LED arrays.…”