Organic-inorganic lead halide perovskite microcrystal (MC) films are attractive candidates for fabricating high-performance large-area self-powered photodetectors (PDs) because of their lower trap state density and higher carrier mobility than their polycrystalline counterparts and more suitability of synthesizing large lateral area films than their single-crystal counterparts. Here, we report on the fabrication of self-powered all-inorganic CsPbBr perovskite MC PDs with high detectivity, using a modified solution synthesis method. The MCs are up to about 10 μm in size, and the MC layer is also about 11 μm in thickness. Under 473 nm laser (100 mW) illumination, the CsPbBr MC PDs show responsivity values of up to 0.172 A W, detectivity values of up to 4.8 × 10 Jones, on/off ratios of up to 1.3 × 10, and linear dynamic ranges of up to 113 dB. These performances are significantly better than those of PDs based on polycrystalline perovskite thin films and comparable with those of PDs based on perovskite single crystals.
All-inorganic halide perovskite is considered as outstanding candidate of organic-inorganic hybrid perovskite due to its superior stability. However, the low solubility of precursor and uncontrollable film growth result in poor film quality and impede the application of polycrystalline films greatly. In this work it is reported on a space-confined growth strategy to overcome the low solubility and fast crystal growth disadvantages via freezing the precursor solution within the gaps of ordered polystyrene sphere templates. Then, the dense CsPbBr 3 polycrystalline films realize low trap density (3.07 × 10 12 cm −3 ) and high carrier mobility (9.27 cm 2 V −1 s −1 ) after stoichiometric modulation. Photodetectors based on these films exhibit high performance in all figures of merit. Specifically, high responsivity up to 216 A W −1 and ultrashort response time (<5 µs) are achieved, which are better than those of all the CsPbBr 3 based PDs. A record detectivity of 7.55 × 10 13 and 3.1 × 10 5 Hz −3 dB bandwidth are also achieved. This work opens the window of high quality all-inorganic halide perovskite polycrystalline films and can be extended to rational application of more optoelectronic devices including solar cells, photoelectrodes, and ray detectors.
Perovskite photodetectors (PDs) with tunable detection wavelength have attracted extensive attention due to the potential application in the field of imaging, machine vision, and artificial intelligence. Most of the perovskite PDs focus on I‐ or Br‐based materials due to their easy preparation techniques. However, their main photodetection capacity is situated in the visible region because of their narrower bandgap. Cl‐based wide bandgap perovskites, such as CsPbCl3, are scarcely reported because of the bad film quality of the spin‐coated Cl‐based perovskite, due to the poor solubility of the precursor. Therefore, ultraviolet detection using high‐quality full inorganic perovskite films, especially with high thermal stability of materials and devices, is still a big challenge. In this work, high‐quality single crystal CsPbCl3 microplatelets (MPs) synthesized by a simple space‐confined growth method at low temperature for near‐ultraviolet (NUV) PDs are reported. The single CsPbCl3 MP PDs demonstrate a decent response to NUV light with a high on/off ratio of 5.6 × 103 and a responsivity of 0.45 A W−1 at 5 V. In addition, the dark current is as low as pA level, leading to detectivity up to 1011 Jones. Moreover, PDs possess good stability and repeatability.
Compared with a single nanowire (NW) or NW array, the simpler preparation process of an NW network (NWN) enables it to be fabricated in large-scale, flexible, and wearable applications of photodetectors (PDs). However, the NWN behaves many microinterfaces (MIs) between NWs, seriously limiting the device performance and stability. Here, we demonstrate a welding strategy for an MAPbI3 NWN, which enhances the crystallinity of the NWN and enhances the radial transmission of photogenerated carriers, leading to a better device performance with ultrahigh stability. Our NWN PDs fabricated by using the welding strategy showed ultrahigh performance with an on/off ratio and detectivity of 2.8 × 104 and 4.16 × 1012 Jones, respectively, which are the best performance for reported metal–semiconductor–metal (MSM) perovskite NWN PDs and are comparable to those of single-NW or NW array PDs. More importantly, our unpackaged NWN PDs show ultrahigh storage stability in air with a humidity of 55–65%, and the flexible NWN PDs can enable 250 bending cycles at different bending radii and 1000 bending cycles at fixed bending radii with no performance degradation being observed. These results indicate our welding strategy is very powerful for improving the performance of the NW device with applications in the wearable field.
Broadband transparent electrodes based on a two-dimensional grid of topological insulator Bi2Se3 are synthesized by a facile selective-area van der Waals epitaxy method. These two-dimensional grid electrodes exhibit high uniformity over large area, outstanding mechanical durability, and excellent chemical resistance to environmental perturbations. Remarkably, the topological grid electrode has high transmittance of more than 85% from the visible to the near-infrared region.
Covalent grafting of methyl groups onto the basal plane of graphene is achieved through a photochemical reaction between graphene and di-tert-butyl peroxide. The methylation of graphene is found to be reversible. The edge of single-layer graphene shows the largest methylation reactivity, which provides a route to tailor the edge state of graphene.
devices in VLC are essential because their response speed, detectivity (D*), and stability determine the quality and speed of the signal acceptance. All-inorganic perovskites are very attractive for their application in the PDs with requirements of high durability, wide-range spectral responses, ultra-high D*, and fast response speed, due to their merits of high thermal stability, tunable bandgaps, high light absorption coefficients, and long carrier diffusion lengths. [2][3][4][5] Particularly, cesium lead bromide (CsPbBr 3 ), a prototypical all-inorganic perovskite with a bandgap energy of 2.4 eV, has been widely used for fabricating solar cells and PDs. [6] The preparation of high-quality CsPbBr 3 films with a large lateral area is crucial for their commercialization. Luchkin et al. fabricated inorganic CsPbBr 3 perovskite solar cells with the best efficiency of 3.9% by using a vacuum deposition process. The poor efficiency was attributed to the off-stoichiometric ratios of the vacuum-processed precursors. [7] Recently, inorganic perovskite quantum dots (QDs) were developed to fabricate perovskite photoelectronic devices, demonstrating decent device performance. [8,9] However, these perovskite films consisted of mosaic QDs capped with a large amount of organic ligands and surface traps, which hinder the carrier transport and limit the device performance. Solutionprocessed CsPbBr 3 polycrystalline (PC) films are an attractive alternative due to better process controllability, endowing them with great potential for large-scale commercial fabrication of perovskite photoelectronic devices. [10][11][12][13] Unfortunately, the fabrication of high-quality CsPbBr 3 PC films via solution processes is challenging. The low solubility of CsBr in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solvents causes insufficient and unbalanced reaction of the precursors, which leads to discontinuous and porous morphology and off-stoichiometric compositions in solution-processed perovskite films. [14,15] Additionally, due to the much lower solubility of CsBr than that of PbBr 2 in the solvents, CsBr behaves as the growth seeds during the nucleation of perovskite crystallites, which aggravates the formation of voids and impurity phases, hindering the achievement of the high-performance PDs. [16] Cesium lead bromide (CsPbBr 3 ) perovskite photodetectors (PDs) are attractive for applications in visible light communication (VLC) due to ultra-high detectivity and fast response speed. However, the fabrication of high-quality CsPbBr 3 polycrystalline films using solution-based process is very challenging. Due to the low solubility of CsBr in precursor solutions, solution-processed CsPbBr 3 films are typically discontinuous and porous, hindering the performance of resulting PDs. Herein, a facile and modified sequential spin-coating method is introduced to prepare high-crystallinity, pinhole-free CsPb 2 Br 5 -CsPbBr 3 perovskite films with an average grain size of ≈1 µm. The hole-transport-layer-free (HTL-free) PDs based on the CsPb ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.