Quasi-Two-Dimensional Halide Perovskite Single Crystal Photodetector

Abstract

The robust material stability of the quasi-two-dimensional (quasi-2D) metal halide perovskites has opened the possibility for their usage instead of three-dimensional (3D) perovskites. Further, devices based on large area single crystal membranes have shown increasing promise for photoelectronic applications. However, growing inch-scale quasi-2D perovskite single crystal membranes (quasi-2D PSCMs) has been fundamentally challenging. Here we report a fast synthetic method for synthesizing inch-scale quasi-2D PSCMs, namely (CHNH) (CHNH) PbI (index n = 1, 2, 3, 4, and ∞), and demonstrate their application in a single-crystal photodetector. A quasi-2D PSCM has been grown at the water-air interface where spontaneous alignment of alkylammonium cations and high chemical potentials enable uniform orientation and fast in-plane growth. Structural, optical, and electrical characterizations have been conducted as a function of quantum well thickness, which is determined by the index n. It is shown that the photodetector based on the quasi-2D PSCM with the smallest quantum well thickness ( n = 1) exhibits a strikingly low dark current of ∼10 A, higher on/off ratio of ∼10, and faster response time in comparison to those of photodetectors based on quasi-2D PSCMs with larger quantum well thickness ( n > 1). Our study paves the way toward the merging the gap between single crystal devices and the emerging quasi-2D perovskite materials.

Light Generation in Lead Halide Perovskite Nanocrystals: LEDs, Color Converters, Lasers, and Other Applications

“…In quasi‐2D LHP‐NCs, ion migration out‐of‐plane planes can be suppressed by an inhomogeneous structure of an inorganic [PbX 6 ] 4− sandwiched by insulating ligands with strong dielectric confinement, which improves the stability of the NCs and resulting devices . However, a side‐effect is that the charge carrier mobility and conductivity is also suppressed by one order of magnitude ( Figure a), leading to a high driving voltage in the resulting LEDs …”

“…a) Comparison of in‐plane and out‐of‐plane mobility and conductivity with respect to the number of monolayer quasi‐2D LHP‐NCs. Reproduced with permission . Copyright 2018, American Chemical Society.…”

“…Hence, the slightly increased bandgap (≈0.3 eV) does not require as high as a voltage to drive the resulting LEDs . As in quasi‐2D LHP‐NCs, insulating ligands arranged in a preferred orientation block the charge carrier transfer out of the [PbX 6 ] 4− plane (Figure a), which could be the dominant factor in the high driving voltage . The current–voltage characteristics of some LEDs using quasi‐2D LHP‐NC emissive films exhibit a low driving voltage, which may be attributed to the leakage current generated by a rough morphology or pinholes in low‐quality emissive films.…”

Switchable Two‐Terminal Transparent Optoelectronic Devices Based on 2D Perovskite

“…Since, ZnO have a rich defect state and are more likely to form an interface state with the perovskite, which prompts the charge tunneling, consequentially, a photoresponse appears. [35][36][37][38] In short, our lithography free two-terminal device can be electrically triggered into on/off states for optoelectronic applications. [35][36][37][38] In short, our lithography free two-terminal device can be electrically triggered into on/off states for optoelectronic applications.…”

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

“…The response speed can be increased by the low trap density and high carrier mobility. Compared to n = 1–2 perovskite nanowire arrays, n = 3 perovskite nanowire arrays integrate lower trap density and higher carrier mobility, yielding photodetectors with a fast response speed of 36.2 µs for the rise and 31.5 µs for decay, respectively . To compare the photodetection performance of nanowires with different crystallinity, the photocurrents of nanowires fabricated by different solvents were measured.…”