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Minutea??Scale Rapid Crystallization of a Highly Dichroic 2D Hybrid Perovskite Crystal toward Efficient Polarizationa??Sensitive Photodetector
摘要： 2D hybrid perovskites demonstrate better performances than 3D counterparts in certain optoelectronic devices, whereas their natural attributes cannot be extracted from microcrystalline films, such as the natural dichroism for polarized light detection. Herein, for the first time, unusual minute-scale rapid crystallization is developed to grow bulk crystals of 2D hybrid perovskite, (FPEA)2PbI4 (1, FPEA is p-fluorophenethylammonium), which enables superior carrier transport property (≈64.1 ns) and low trap density (≈1010 cm?3). The rapid growth rate of 27.3 mm3 h?1 is almost two orders of magnitude higher than for other 2D counterparts. Strikingly, its natural quantum-confined motif results in extraordinary dichroism with optical absorption ratio αc/αa ≈ 2.05, revealing great promises for polarized light detection. Consequently, crystal-based photodetectors exhibit large photocurrent dichroic ratio Imax/Imin ≈ 2.1, fast response time (400 μs), and high detectivity (1011 Jones) to the polarized light. This is the record-fast crystallization of highly dichroic 2D hybrid perovskites, which opens a new prospect for their future optoelectronic device applications.
关键词： optical dichroism,rapid crystallization,polarized light detectors,hybrid perovskites
更新于2025-09-19 17:13:59
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A novel approach for preparation of CH3NH3PbBr3 via direct transformation of electrodeposited PbO2 for photodetector application
摘要： Organic–inorganic hybrid perovskites are crystals with efficient light absorption, high charge carrier mobility and long electron/hole diffusion path that have been developed to enhance sunlight energy application. In particular, lead-based compounds by establishing excellent performance in 3rd generation solar cells led to an increased interest in testing them in other areas such as photodetectors, diodes, and transistors. Herein, we report a simple, scalable and versatile fabrication process of CH3NH3PbBr3 layer through electrodeposition technique without using a glove box or a high vacuum system. Measurements demonstrated that a high quality crystalline structure in a pinhole free perovskite layer was obtained. The fabricated photodetector devices made of electrodeposited MAPbBr3 films displayed significant performance with the on/off current ratio of 3 × 106 under white light radiation at 0.1 V bias voltage. Increasing the thickness of photoactive absorber layer up to 1 μm led to 7% external quantum efficiency and 34.4% improvement of EQE compared to 546 nm film.
关键词： photodetector,electrodeposition,MAPbBr3,PbO2,Organic–inorganic hybrid perovskites
更新于2025-09-11 14:15:04
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Hydrophilicity and Water Contact Angle on Methylammonium Lead Iodide
摘要： Surface properties are often assessed with measurements of the contact angle of a water drop. The process is however flawed for the very important class of hybrid perovskite materials, extensively employed in solar cells and optoelectronics research, because they are water soluble and their surface degrades during contact angle measurements. While hybrid perovskites are considered to be highly hydrophilic, a contact angle with water of 83° can be measured, as if they were almost hydrophobic. By combining experiments and simulations, the actual value is explained as the result of the interaction of water with degraded superficial layers that form over sub-millisecond time scale at the water/perovskite interface. The models are validated against contact angle measurements for water on a variety of substrates, and are referenced to with the Young–Dupré relation between liquid–solid adhesion and contact angle. Present work reconciles the hydrophilic nature of methylammonium lead iodide with the apparent hydrophobic behavior in contact angle measurements, proposing a methodology for the study of contact angle on evolving substrates.
关键词： hybrid perovskites,atomistic simulations,degradation,molecular dynamics,PbI2
更新于2025-09-09 09:28:46
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Single crystal hybrid perovskite field-effect transistors
摘要： The fields of photovoltaics, photodetection and light emission have seen tremendous activity in recent years with the advent of hybrid organic-inorganic perovskites. Yet, there have been far fewer reports of perovskite-based field-effect transistors. The lateral and interfacial transport requirements of transistors make them particularly vulnerable to surface contamination and defects rife in polycrystalline films and bulk single crystals. Here, we demonstrate a spatially-confined inverse temperature crystallization strategy which synthesizes micrometre-thin single crystals of methylammonium lead halide perovskites MAPbX3 (X = Cl, Br, I) with sub-nanometer surface roughness and very low surface contamination. These benefit the integration of MAPbX3 crystals into ambipolar transistors and yield record, room-temperature field-effect mobility up to 4.7 and 1.5 cm2 V?1 s?1 in p and n channel devices respectively, with 104 to 105 on-off ratio and low turn-on voltages. This work paves the way for integrating hybrid perovskite crystals into printed, flexible and transparent electronics.
关键词： hybrid perovskites,field-effect transistors,single crystals,ambipolar transport,inverse temperature crystallization
更新于2025-09-09 09:28:46
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Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice
摘要： Materials science evolves to a state where the composition and structure of a crystal can be controlled almost at will. Given that a composition meets basic requirements of stoichiometry, steric demands, and charge neutrality, researchers are now able to investigate a wide range of compounds theoretically and, under various experimental conditions, select the constituting fragments of a crystal. One intriguing playground for such materials design is the perovskite structure. While a game of mixing and matching ions has been played successfully for about 150 years within the limits of inorganic compounds, the recent advances in organic–inorganic hybrid perovskite photovoltaics have triggered the inclusion of organic ions. Organic ions can be incorporated on all sites of the perovskite structure, leading to hybrid (double, triple, etc.) perovskites and inverse (hybrid) perovskites. Examples for each of these cases are known, even with all three sites occupied by organic molecules. While this change from monatomic ions to molecular species is accompanied with increased complexity, it shows that concepts from traditional inorganic perovskites are transferable to the novel hybrid materials. The increased compositional space holds promising new possibilities and applications for the universe of perovskite materials.
关键词： hybrid perovskites,inverse hybrid perovskites,materials design,photovoltaic,DFT calculations
更新于2025-09-04 15:30:14
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Layered Hybrid Perovskites for Highly Efficient Three-Photon Absorbers: Theory and Experimental Observation
摘要： Multiphoton absorption may find many technological applications, such as enhancing the conversion efficiency of solar cells by the utilization of sub-band-energy photons, below-bandgap photodetection through the simultaneous absorption of several infrared photons for photocurrent generation, or light frequency upconversion for high-resolution, 3D imaging. To enhance multiphoton absorption in semiconducting materials, one of the strategies is to explore low-dimensional excitons. Here, a quantum perturbation theory on a giant enhancement in three-photon absorption (3PA) arising from 2D excitons in multilayered crystals of organic–inorganic hybrid perovskites is presented. The maximal 3PA coefficient is predicted to be in the range of 2–7 cm3 GW?2 at 1100 nm, the largest values reported so far for any 2D and bulk semiconductors at room temperature. Excellent agreement between theory and the experimental findings unambiguously demonstrates a pivotal role in the enhancement of 3PA played by 2D excitons. The theory predicts that the resonant 3PA coefficient should be enhanced further by at least two orders of magnitude with very low temperature. The findings are essential for understanding giant 3PA arising from 2D excitons in layered hybrid perovskites and may open new pathways for highly efficient conversion from infrared light energy to either electrical energy or higher-frequency light emission/lasing.
关键词： nonlinear optics,three-photon absorbers,2D excitons,hybrid perovskites
更新于2025-09-04 15:30:14