Layered‐Perovskite Nanowires with Long‐Range Orientational Order for Ultrasensitive Photodetectors

Abstract

2D layered metal‐halide perovskites combine efficient exciton radiative recombination in crystal interior with long‐distance free‐carrier conduction at layer edges, which are promising candidates for realizing high‐performance photovoltaic, light‐emission and photodetection devices. The anisotropic electrical conductivity in layered perovskites imposes an additional requirement of orientational control for enabling favorable charge transport. However, rational fabrication of single‐crystalline nanostructures with pure crystallographic orientation is still elusive. Herein, large‐scale pure (101)‐orientated 2D‐perovskite single‐crystalline nanowire arrays are realized by combining solvent engineering with the capillary‐bridge lithography technique. Ordered nucleation at liquid–air interface and unidirectional growth along the dewetting direction are demonstrated by fluorescence microscopy and grazing‐incidence X‐ray scattering in discrete capillary bridges. In consideration of crystal interior exhibiting high resistance arising from the serial insulating organic barriers and ultrafast dissociation of excitons to generate long‐lived free carriers at layer edges, ultrasensitive photodetectors are demonstrated with average responsivity exceeding 1.1 × 104 A W−1 and detectivity exceeding 9.1 × 1015 Jones.

Ultrasensitive Photodetectors Promoted by Interfacial Charge Transfer from Layered Perovskites to Chemical Vapor Deposition‐Grown MoS2

“…To facilitate the charge transfer between layered perovskites and MoS 2 , crystallographic orientation of layered perovskites is significant. Thanks to the self‐assembly behavior of bulky organic cations and perovskite slabs at liquid–air interface, [ 16,36 ] pure crystallographic orientation can be achieved by a hot spin‐coating process (see Experimental Section). Due to the preferential crystallization at liquid–air interface, this crystallographic orientation is insensitive to substrate, which has been demonstrated in the fabrication of photovoltaic devices.…”

“…Layered perovskites, a category of natural quantum wells self‐assembled by conductive few‐layer perovskites and insulating bulky organic cations, [ 10–14 ] have been proved with ultralow noise levels stemming from the high‐resistance interlayer cations. [ 15–17 ] These self‐assembled quantum wells also exhibit considerable photocurrent conduction along layer edges, but requires sophisticated fabrication of single‐crystalline nanowires. [ 15,16 ] 2D transition‐metal dichalcogenides (TMDCs) and graphene are prototypical materials with inherent high carrier mobility and strong light–matter interactions, [ 18–20 ] thus suitable for photodetection applications.…”

“…[ 15–17 ] These self‐assembled quantum wells also exhibit considerable photocurrent conduction along layer edges, but requires sophisticated fabrication of single‐crystalline nanowires. [ 15,16 ] 2D transition‐metal dichalcogenides (TMDCs) and graphene are prototypical materials with inherent high carrier mobility and strong light–matter interactions, [ 18–20 ] thus suitable for photodetection applications. [ 2,21,22 ] However, limited light absorption originating from their atomic thickness and high conductivity in dark state inhibit both responsivity and detectivity of photodetectors.…”

Influence of the Vibrational Modes from the Organic Moieties in 2D Lead Halides on Excitonic Recombination and Phase Transition

“…[ 1–4 ] Owned for their unique optoelectronic properties, these semiconductors are prominent in the development of a series of new‐generation photonic devices such as solar cells, [ 5–8 ] LEDs, [ 9–11 ] and photodetectors. [ 12–14 ] Their structure is commonly compared to 3D metal halide perovskites with structure ABX 3 (where A is monovalent cation, B is a divalent cation, more frequently Pb 2+ and Sn 2+ , and X is a halide different from F − ) and, very commonly, are regarded as reduced dimensional perovskites or 2D perovskites. [ 2 ] The fundamental structural difference between 3D perovskites and 2D metal halides is that, in the latter, the A‐site cation is too large to fit the cavity within the octahedrons, generating a layered structure where the inorganic slabs are separated by a bilayer of organic cations ( Figure a).…”

Anisotropic shape of CsPbBr3 colloidal nanocrystals: from 1D to 2D confinement effects

“…26,32,33 Long nanowires can be cut to obtain nanoobjects with two confinement directions leading to nanorods or nanosticks (NSTs). 34 Several applications have also been proposed that could exploit such nanostructured perovskite materials, as for example, low-threshold lasers, [35][36][37] LEDs, 38,39 photodetectors 40,41 and flexible optoelectronic devices. 42 Size effects were mainly addressed in NPLs dispersed in solutions by measuring absorption or PL spectra at room temperature.…”