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Investigation on crystallization of CH3NH3PbI3 perovskite and its intermediate phase from polar aprotic solvents
摘要： Perovskite films are usually fabricated by solution-processed method due to its low cost and ease of fabrication. The organic solvent plays multiple roles in growth of perovskites. Here, we investigate the growth of methylammonium lead iodide perovskite and its intermediate phase from micro-droplets containing with various solvents. Perovskite intermediate phase inclines to grow in the direction of its (020) plane from polar aprotic solvents at low temperature. At high temperature, the growth of perovskites depends on the structure of solvent molecules. The intermediate phase still grows from the solvents with short chain structure. It tends to form smooth films containing radial domains with dimension in tens of microns, which consist of nanocrystals due to annealing effects. However, perovskite grains grow directly from the solvents with ring structure. It tends to form smooth thin films by joining the large hexagonal perovskite crystals together. It provides a guidance to prepare high quality perovskite films for high performance optoelectronic devices.
关键词： micro-droplet,polar aprotic solvent,perovskite,crystallization
更新于2025-09-04 15:30:14
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Multi-inch single-crystalline perovskite membrane for high-detectivity flexible photosensors
摘要： Single crystalline perovskites exhibit high optical absorption, long carrier lifetime, large carrier mobility, low trap-state-density and high defect tolerance. Unfortunately, all single crystalline perovskites attained so far are limited to bulk single crystals and small area wafers. As such, it is impossible to design highly demanded ?exible single-crystalline electronics and wearable devices including displays, touch sensing devices, transistors, etc. Herein we report a method of induced peripheral crystallization to prepare large area ?exible single-crystalline membrane (SCM) of phenylethylamine lead iodide (C6H5C2H4NH3)2PbI4 with area exceeding 2500 mm2 and thinness as little as 0.6 μm. The ultrathin ?exible SCM exhibits ultralow defect density, superior uniformity and long-term stability. Using the superior ultrathin membrane, a series of ?exible photosensors were designed and fabricated to exhibit very high external quantum ef?ciency of 26530%, responsivity of 98.17 A W?1 and detectivity as much as 1.62 × 1015 cm Hz1/2 W?1 (Jones).
关键词： high-detectivity,single-crystalline perovskite,flexible photosensors,induced peripheral crystallization,ultrathin membrane
更新于2025-09-04 15:30:14
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Phosphomolybdic acid as an efficient hole injection material in perovskite optoelectronic devices
摘要： Efficient perovskite devices consist of a perovskite film sandwiched between charge selective layers, in order to avoid non-radiative recombination. A common metal oxide used as a p-type or hole transport layer is molybdenum oxide. MoO3 is of particular interest for its very large work function, which allows it to be used both as an interfacial charge transfer material and a dopant for organic semiconductors. However, high quality and high work function MoO3 is typically thermally evaporated in a vacuum. An alternative solution-processable high work function material is phosphomolybdic acid (PMA), which is stable, commercially available and environmentally friendly. In this Communication, we show the first application of PMA in efficient vacuum processed perovskite devices. We found that the direct growth of perovskite films onto PMA leads to strong charge carrier recombination, hindering the solar cell photovoltage. Using an energetically suitable selective transport layer placed between PMA and the perovskite film, solar cells with efficiency >13% as well as LEDs with promising quantum efficiency can be obtained.
关键词： LEDs,optoelectronic devices,perovskite,hole injection material,phosphomolybdic acid,solar cells
更新于2025-09-04 15:30:14
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X-ray study of anisotropically shaped metal halide perovskite nanoparticles in tubular pores
摘要： Recently, we have reported that metal halide perovskite nanoparticles formed in nanoporous alumina and silicon thin films exhibit blue shifted photoluminescence due to spatial confinement, thus allowing for color tuning of the emission by varying the pore size. While perovskite nanoparticles grown in nanoporous alumina films have been integrated into LEDs, similar approaches have failed with silicon. Here, we report the results of investigating the structure of the alumina pore system and the perovskite crystallites forming within. We use two x-ray diffraction techniques, namely, small-angle x-ray scattering (SAXS) and high-energy microbeam wide-angle x-ray scattering (WAXS). SAXS reveals that the alumina pore system diffracts like regularly arranged tubes with the average diameter and nearest neighbor distance of 12 nm and 20 nm, respectively. High-energy microbeam WAXS shows that perovskite nanoparticles within the nanoporous alumina have a distinctly anisotropic shape with the average particle length along and perpendicular to the pore axis of 26 nm and 13 nm, respectively. In contrast, no shape anisotropy has been detected for nanoparticles inside the silicon pores in a previous study. This suggests that utilizing nanoporous alumina has a twofold advantage. First, the tubular alumina pores, spanning the entire insulating film, offer percolated paths for the perovskite to fill. Second, the elongation of the nanoparticles in the tubular alumina pores can be expected to aid device performance as the length of the nanoparticles approaches the active layer thickness (ca. 40 nm) of LEDs, while the small diameter of the crystallites accounts for the observed blue shifted emission.
关键词： LEDs,anisotropic shape,nanoporous alumina,SAXS,WAXS,nanoparticles,metal halide perovskite
更新于2025-09-04 15:30:14
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Confinement of Perovskite‐QDs within a Single MOF Crystal for Significantly Enhanced Multiphoton Excited Luminescence
摘要： The development of the photostable higher-order multiphoton-excited (MPE) upconversion single microcrystalline material is fundamentally and technologically important, but very challenging. Here, up to five-photon excited luminescence in a host–guest metal–organic framework (MOF) and perovskite quantum dot (QD) hybrid single crystal ZJU-28?MAPbBr3 is shown via an in situ growth approach. Such a MOF strategy not only results in a high QD loading concentration, but also significantly diminishes the aggregation-caused quenching (ACQ) effect, provides effective surface passivation, and greatly reduces the contact of the QDs with the external bad atmosphere due to the confinement effect and protection of the framework. These advantages make the resulting ZJU-28?MAPbBr3 single crystals possess high PLQY of ≈51.1%, a high multiphoton action cross-sections that can rival the current highest record (measured in toluene solution), and excellent photostability. These findings liberate the excellent luminescence and nonlinear optical properties of perovskite QDs from the solution system to the solid single-crystal system, which provide a new avenue for the exploitation of high-performance multiphoton excited hybrid single microcrystal for future optoelectronic and micro–nano photonic integration applications.
关键词： single crystals,multiphoton excited luminescence,metal–organic frameworks,perovskite-QDs
更新于2025-09-04 15:30:14
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Multiple Resistive Switching Behaviours of CH3NH3PbI3 Perovskite film with Different Metal Electrodes
摘要： The utilization of defects in organic-inorganic hybrid perovskite materials such as CH3NH3PbI3 is beneficial for memory applications. In this work, a simple CH3NH3PbI3 memory device with various commonly used electrodes such as aluminium (Al), silver (Ag), and gold (Au) yielded different switching behaviours. Using Al in ITO/CH3NH3PbI3/Al device reveals Resistive Random Access Memory (ReRAM) behaviour with a SET voltage of 4.5 V and can be RESET by applying a negative sweep voltage above 1.3 V due to the formation of iodide vacancy filament. Interestingly, by using Ag and Au cathodes to replace Al, yielded Write-Once-Read-Many (WORM) resistive switching characteristics. The conversion process from OFF to ON occur at around 4.7 V and 4.0 V for Ag and Au, respectively. The “shorting effect” remains even though a reverse voltage was applied indicating data retention. These fabricated devices could contribute to further understanding of selecting the right electrodes and open up new possibility of studies in the direction of resistive switching memory applications.
关键词： organic-inorganic perovskite,resistive switching,filamentary conduction,charge trapping
更新于2025-09-04 15:30:14