CH3 NH3 PbBr3 Research Articles

Low-Noise and Large-Linear-Dynamic-Range Photodetectors Based on Hybrid-Perovskite Thin-Single-Crystals.

Organic-inorganic halide perovskites are promising photodetector materials due to their strong absorption, large carrier mobility, and easily tunable bandgap. Up to now, perovskite photodetectors are mainly based on polycrystalline thin films, which have some undesired properties such as large defective grain boundaries hindering the further improvement of the detector performance. Here, perovskite thin-single-crystal (TSC) photodetectors are fabricated with a vertical p-i-n structure. Due to the absence of grain-boundaries, the trap densities of TSCs are 10-100 folds lower than that of polycrystalline thin films. The photodetectors based on CH3 NH3 PbBr3 and CH3 NH3 PbI3 TSCs show low noise of 1-2 fA Hz-1/2 , yielding a high specific detectivity of 1.5 × 1013 cm Hz1/2 W-1 . The absence of grain boundaries reduces charge recombination and enables a linear response under strong light, superior to polycrystalline photodetectors. The CH3 NH3 PbBr3 photodetectors show a linear response to green light from 0.35 pW cm-2 to 2.1 W cm-2 , corresponding to a linear dynamic range of 256 dB.

Photostriction of CH3 NH3 PbBr3 Perovskite Crystals.

Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices.

Top-Down Fabrication of Stable Methylammonium Lead Halide Perovskite Nanocrystals by Employing a Mixture of Ligands as Coordinating Solvents.

A top-down method is demonstrated for the fabrication of CH3 NH3 PbBr3 and CH3 NH3 PbI3 perovskite nanocrystals, employing a mixture of ligands oleic acid and oleylamine as coordinating solvents. This approach avoids the use of any polar solvents, skips multiple reaction steps by employing a simple ultrasonic treatment of the perovskite precursors, and yields rather monodisperse blue-, green-, and red-emitting methylammonium lead halide nanocrystals with a high photoluminescence quantum yield (up to 72 % for the green-emitting nanocrystals) and remarkably improved stability. After discussing all relevant reaction parameters, the green-emitting CH3 NH3 PbBr3 nanocrystals are employed as a component of down-conversion white-light-emitting devices.

CH3 NH3 PbBr3 Perovskite Nanocrystals as Efficient Light-Harvesting Antenna for Fluorescence Resonance Energy Transfer.

Hybrid perovskites have created enormous research interest as a low-cost material for high-performance photovoltaic devices, light-emitting diodes, photodetectors, memory devices and sensors. Perovskite materials in nanocrystal form that display intense luminescence due to the quantum confinement effect were found to be particularly suitable for most of these applications. However, the potential use of perovskite nanocrystals as a light-harvesting antenna for possible applications in artificial photosynthesis systems is not yet explored. In the present work, we study the light-harvesting antenna properties of luminescent methylammonium lead bromide (CH3 NH3 PbBr3 )-based perovskite nanocrystals using fluorescent dyes (rhodamine B, rhodamine 101, and nile red) as energy acceptors. Our studies revealed that CH3 NH3 PbBr3 nanocrystals are an excellent light-harvesting antenna, and efficient fluorescence resonance energy transfer occurs from the nanocrystals to fluorescent dyes. Further, the energy transfer efficiency is found to be highly dependent on the number of anchoring groups and binding ability of the dyes to the surface of the nanocrystals. These observations may have significant implications for perovskite-based light-harvesting devices and their possible use in artificial photosynthesis systems.

In Situ Growth of 120 cm2 CH3 NH3 PbBr3 Perovskite Crystal Film on FTO Glass for Narrowband-Photodetectors.

Organometal trihalide perovskites have been attracting intense attention due to their enthralling optoelectric characteristics. Thus far, most applications focus on polycrystalline perovskite, which however, is overshadowed by single crystal perovskite with superior properties such as low trap density, high mobility, and long carrier diffusion length. In spite of the inherent advantages and significant optoelectronic applications in solar cells and photodetectors, the fabrication of large-area laminar perovskite single crystals is challenging. In this report, an ingenious space-limited inverse temperature crystallization method is first demonstrated to the in situ synthesis of 120 cm2 large-area CH3 NH3 PbBr3 crystal film on fluorine-doped tin oxide (FTO) glass. Such CH3 NH3 PbBr3 perovskite crystal film is successfully applied to narrowband photodetectors, which enables a broad linear response range of 10-4 -102 mW cm-2 , 3 dB cutoff frequency (f 3 dB ) of ≈110 kHz, and high narrow response under low bias -1 V.

Colloidal Synthesis of CH3 NH3 PbBr3 Nanoplatelets with Polarized Emission through Self-Organization.

We report a combined experimental and theoretical study of the synthesis of CH3 NH3 PbBr3 nanoplatelets through self-organization. Shape transformation from spherical nanodots to square or rectangular nanoplatelets can be achieved by keeping the preformed colloidal nanocrystals at a high concentration (3.5 mg mL-1 ) for 3 days, or combining the synthesis of nanodots with self-organization. The average thickness of the resulting CH3 NH3 PbBr3 nanoplatelets is similar to the size of the original nanoparticles, and we also noticed several nanoplatelets with circular or square holes, suggesting that the shape transformation experienced a self-organization process through dipole-dipole interactions along with a realignment of dipolar vectors. Additionally, the CH3 NH3 PbBr3 nanoplatelets exhibit excellent polarized emissions for stretched CH3 NH3 PbBr3 nanoplatelets embedded in a polymer composite film, showing advantageous photoluminescence properties for display backlights.

High-Performance Color-Tunable Perovskite Light Emitting Devices through Structural Modulation from Bulk to Layered Film.

Adding 2-phenoxyethylamine (POEA) into a CH3 NH3 PbBr3 precursor solution can modulate the organic-inorganic hybrid perovskite structure from bulk to layered, with a photoluminescence and electroluminescence shift from green to blue. Meanwhile, POEA can passivate the CH3 NH3 PbBr3 surface and help to obtain a pure CH3 NH3 PbBr3 phase, leading to an improvement of the external quantum efficiency to nearly 3% in CH3 NH3 PbBr3 LED.

High-Purity Hybrid Organolead Halide Perovskite Nanoparticles Obtained by Pulsed-Laser Irradiation in Liquid.

Nanoparticles of hybrid organic-inorganic perovskites have attracted a great deal of attention due to their variety of optoelectronic properties, their low cost, and their easier integration into devices with complex geometry, compared with microcrystalline, thin-film, or bulk metal halides. Here we present a novel one-step synthesis of organolead bromide perovskite nanocrystals based on pulsed-laser irradiation in a liquid environment (PLIL). Starting from a bulk CH3 NH3 PbBr3 crystal, our PLIL procedure does not involve the use of high-boiling-point polar solvents or templating agents, and runs at room temperature. The resulting nanoparticles are characterized by high crystallinity and are completely free of any microscopic product or organic coating layer. We also demonstrate the straightforward inclusion of laser-generated perovskite nanocrystals in a polymeric matrix to form a nanocomposite with single- and two-photon luminescence properties.

Ultrastable, Highly Luminescent Organic-Inorganic Perovskite-Polymer Composite Films.

A simple yet general swelling-deswelling microencapsulation strategy has been developed to achieve well dispersed and intimately passivated crystalline organic-inorganic perovskites nanoparticles within polymer matrixes and results in a series of highly luminescent CH3 NH3 PbBr3 (MAPbBr3 )-polymer composite films with unprecedented water and thermal stabilities and superior color purity.

The Luminescence of CH3 NH3 PbBr3 Perovskite Nanoparticles Crests the Summit and Their Photostability under Wet Conditions is Enhanced.

CH3 NH3 PbBr3 perovskite nanoparticles (PAD ) are prepared with a photoluminescence quantum yield of ≈100% in air atmosphere by using the quasi-spherical shaped 2-adamantylammonium bromide (ADBr) as the only capping ligand. The photostability under wet conditions of this kind of nanoparticles is enhanced by using cucurbit[7]uril-adamantylammonium (AD@CB) host-guest complexes as the capping ligand.

Tunable bandgap in hybrid perovskite CH3NH3Pb(Br3−yXy) single crystals and photodetector applications

We report the synthesis of CH3NH3Pb(Br3−yXy) (X=Cl and I) single crystals via a stepwise temperature control approach. High-quality CH3NH3Pb(Br3−yXy) crystals with a tunable bandgap from 1.92eV to 2.53eV have been prepared successfully in this way. And further experiments revealed the influence of halogen content and preparation temperature on the structural and optical properties of these crystals. It is observed that chlorine can lower the critical nucleation energy, which results in crystallizing at lower temperature with the chlorine content increasing, while the nucleation energy increases slowly with increasing iodine content. Moreover, in contrast to Frank–van der Merwe growth with low heating rate, high heating rate leads to a mass of small size single crystals and Stranski-Krastanov growth. The single crystals with tunable band gap and impressive characteristics enable us to fabricate high performance photodetectors for different wavelengths.

Solution-Grown Monocrystalline Hybrid Perovskite Films for Hole-Transporter-Free Solar Cells.

High-quality perovskite monocrystalline films are successfully grown through cavitation-triggered asymmetric crystallization. These films enable a simple cell structure, ITO/CH3 NH3 PbBr3 /Au, with near 100% internal quantum efficiency, promising power conversion efficiencies (PCEs) >5%, and superior stability for prototype cells. Furthermore, the monocrystalline devices using a hole-transporter-free structure yield PCEs ≈6.5%, the highest among other similar-structured CH3 NH3 PbBr3 solar cells to date.

Self-template-directed synthesis of porous perovskite nanowires at room temperature for high-performance visible-light photodetectors.

The unique optoelectronic properties and promising photovoltaic applications of organolead halide perovskites have driven the exploration of facile strategies to synthesize organometal halide perovskites and corresponding hybrid materials and devices. Currently, the preparation of CH3 NH3 PbBr3 perovskite nanowires, especially those with porous features, is still a great challenge. An efficient self-template-directed synthesis of high-quality porous CH3 NH3 PbBr3 perovskite nanowires in solution at room temperature using the Pb-containing precursor nanowires as both the sacrificial template and the Pb(2+) source in the presence of CH3 NH3 Br and HBr is now presented. The initial formation of CH3 NH3 PbBr3 perovskite layers on the surface of the precursor nanowires and the following dissolution of the organic component of the latter led to the formation of mesopores and the preservation of the 1D morphology. Furthermore, the perovskite nanowires are potential materials for visible-light photodetectors with high sensitivity and stability.

Multicolored organic/inorganic hybrid perovskite light-emitting diodes.

Bright organic/inorganic hybrid perov-skite light-emitting diodes (PrLEDs) are realized by using CH3 NH3 PbBr3 as an emitting layer and self-organized buffer hole-injection layer (Buf-HIL). The PrLEDs show high luminance, current efficiency, and EQE of 417 cd m(-2) , 0.577 cd A(-1) , and 0.125%, respectively. Buf-HIL can facilitate hole injection into CH3 NH3 PbBr3 as well as block exciton quenching.

Planar CH3NH3PbBr3 hybrid solar cells with 10.4% power conversion efficiency, fabricated by controlled crystallization in the spin-coating process.

A power conversion efficiency of 10.4% is demonstrated in planar CH3 NH3 PbBr3 hybrid solar cells without hysteresis of the J-V curve, by way of controlled crystallization in the spin-coating process. The high efficiency is attributed to the formation of a dense CH3 NH3 PbBr3 thin film by the introduction of HBr solution because the HBr increases the solubility of the CH3 NH3 PbBr3 and forms a thinner CH3 NH3 PbBr3 layer with full surface coverage.