Methylammonium Acetate Research Articles

Enhanced amplified spontaneous emission performance through effective regulation of phase distribution in Ruddlesden-Popper perovskite films.

Ruddlesden-Popper (RP) perovskites promise next-generation gain media for laser devices. However, most RP perovskite lasers are still suffering from inferior performance characteristics, such as inadequate energy transfer, unstable emission, and short lifetime. To address the above problems, high crystalline quality, compact, and smooth PEA2FA2Pb3Br10 films with uniform phase distribution were successfully prepared by ionic liquid (IL) methylammonium acetate (MAAc) in an air environment. Compared with the PEA2FA2Pb3Br10 film prepared by the traditional solvent dimethyl sulfoxide (DMSO), an enhanced amplified spontaneous emission (ASE) with a lower threshold of 58 µJ·cm-2 from the MAAc-treated film was obtained under nanosecond laser excitation. The transient absorption (TA) spectroscopy revealed that a uniform phase distribution and more efficient energy transfer processes were achieved in the PEA2FA2Pb3Br10-MAAc film, leading to an enhanced band-to-band spontaneous emission process. Furthermore, the films exhibited better stability, showing no signs of degradation under the 120 min pulsed laser pumping in air and stability of ASE spectra at even 95% humidity conditions. This study provides an important foundation for achieving high-performance optically pumped lasers based on the unique RP perovskites.

Solution chemistry strategies to construct a stable MAPbI3 film toward high performance of amplified spontaneous emission

Lead-halide perovskites are being explored as potential light sources for short-distance data communication lasers. However, their practical applications are hindered by defects and poor stability. Ionic liquids (ILs), which are known for their environmentally friendly properties, are being investigated as alternative solvents to address these issues. In this study, methylammonium propionate (MAP), a more viscous IL solvent, was employed to regulate the crystallization process of the perovskite films through the strength of Lewis adducts. Compared with another frequently-used IL, methylammonium acetate (MAAc), the use of MAP solvent was observed to have a significant influence on the morphology and crystalline characteristics of the prepared MAPbI3 film. The findings of this comparative study provide strong evidence for the viability and preferability of using MAP solvent over MAAc in the preparation of MAPbI3 films, specifically for achieving an improved ASE performance and stability. The threshold of the MAPbI3-MAP film was only 12 μJ cm−2, which is lower than one-fourth of that observed for the MAPbI3-MAAc film (56 μJ cm−2) under nanosecond laser excitation. In addition, MAP-based devices can maintain stable ASE output emissions under harsh environments of long-term stimulation and high-humidity preservation.

Ionic liquid tailoring defect/interface-induced recombination loss toward efficient Dion-Jacobson quasi-2D perovskite solar cells

Dion-Jacobson (DJ) quasi-two-dimensional (quasi-2D) perovskites have emerged as a potential photovoltaic material due to their versatile n-layer variation and superior stable structure. However, compared to their three-dimensional counterparts, the power conversion efficiency (PCE) of quasi-2D perovskite solar cells (PSCs) reported to date still lags behind the detailed balance (DB) limit for single-junction PSCs, which derives from the presence of non-radiative recombination loss. Herein, we demonstrated that the defect/interface-induced recombination loss in DJ quasi-2D PSCs could be significantly suppressed by introducing a green ionic liquid methylammonium acetate (MAAc) into (BDA)(MA)4Pb5I16 (n = 5) (BDA, 1,4-butanediamine) perovskite precursor. Both the film quality of 2D perovskites and the interfacial property of perovskite/charge transporting layer (CTL) were improved after introducing MAAc in precursor solution. Correspondingly, a champion PCE of 18.76 % with a remarkable open-circuit voltage (Voc) of 1.24 V was achieved. Through the quantitative loss analysis, which involved the calculation of photovoltaic parameters relative to DB limit and quasi-Fermi level splitting values, the improvement of PCE and Voc by introducing MAAc was mainly attributed to the reduction of defects in perovskite films and at perovskite/CTL interfaces, and the optimization of interfacial energy-level alignment. The present work provides a green solvent strategy for improving the performance of quasi-2D PSCs, and offers an insight into the fundamental physics of non-radiative recombination loss tailored by ionic liquid.

Integration of Large-Area Halide Perovskite Single Crystals and Substrates via Chemical Welding Using an Ionic Liquid for Applications in X-ray Detection.

The large carrier lifetime mobility product and strong stopping power for high-energy X-rays make halide perovskites an attractive candidate for next-generation X-ray detectors. In particular, high-energy X-rays in the range of several tens of keV require halide perovskite absorber layers with thicknesses exceeding a few millimeters. To avoid carrier scattering caused by grain boundaries at such thicknesses, the utilization of single crystals is desirable. Large-area single crystals are predominantly grown in a freestanding form, and integration onto a substrate is necessary for the fabrication of commercial devices. However, an effective method for integrating large single crystals onto a substrate has not yet been developed. In this study, a large-area (20 cm2) MAPbBr3 single crystal is bonded to an indium tin oxide (ITO) substrate using an ionic liquid, showing strong adhesion strength of 164 kPa. X-ray detectors based on ITO/MAPbBr3 single crystal bonded by methylammonium acetate achieved excellent sensitivity of 91,200 μC Gyair-1 cm-2, the highest among substrate-integrated halide perovskite single crystal X-ray detectors.

The characteristics of hole-transport material-free perovskite solar cells with carbon electrode made by using ion liquid methylammonium acetate solvent

Ion liquid is one of the eco-friendly solvent which has many special properties such as high viscosity, low vapor pressure and incombustibility and also has the polarity which can dissolve the perovskite precursor and thus it has a potency which can replace the toxic solvent including dimethylformamide (DMF) and dimethylsulfoxide (DMSO). This work researched the characteristics of perovskite and the influence on the performance of hole transport material-free perovskite solar cells with carbon electrode when we use ion liquid – methylammonium acetate (MAAc) as the solvent of precursor. Perovskite film prepared by using ion liquid is more even and denser than one using DMF and we could improve its crystallinity and increase the crystal size of perovskite. Analysis result shows that the nonradiative recombination of devices was decreased and the open circuit voltage could be improved when we using MAAc instead of DMF. The efficiency of device is 15.16%; higher than the control (13.18%) and especially its stability was maintained 90% of initial value after 1500 h without any seal when the relative humidity was 80%.

Sequential Co-Passivation in InAs Colloidal Quantum Dot Solids Enables Efficient Near-Infrared Photodetectors.

III-V colloidal quantum dots (CQDs) are promising materials for optoelectronic applications, for they avoid heavy metals while achieving absorption spanning the visible to the infrared (IR). However, the covalent nature of III-V CQDs requires the development of new passivation strategies to fabricate conductive CQD solids for optoelectronics: this work shows herein that ligand exchanges, previously developed in II-VI and IV-VI quantum dots and employing a single ligand, do not fully passivate CQDs, and that this curtails device efficiency. Guided by density functional theory (DFT) simulations, this work develops a co-passivation strategy to fabricate indium arsenide CQD photodetectors, an approach that employs the combination of X-type methyl ammonium acetate (MaAc) and Z-type ligands InBr3 . This approach maintains charge carrier mobility and improves passivation, seen in a 25% decrease in Stokes shift, a fourfold reduction in the rate of first-exciton absorption linewidth broadening over time-under-stress, and leads to a doubling in photoluminescence (PL) lifetime. The resulting devices show 37% external quantum efficiency (EQE) at 950nm, the highest value reported for InAs CQD photodetectors.

Competitive Solvation-Induced Interphases Enable Highly Reversible Zn Anodes

Aqueous Zn-metal batteries have been recognized as promising energy storage devices due to their high theoretical energy density and cost-effectiveness. However, side reactions and Zn dendrite growth during cycling limit their practical application. Herein, we investigated methylammonium acetate as an electrolyte additive to enhance the reversibility and stability of the Zn anode. The results revealed that the acetate anions would competitively engage the Zn2+ solvation structure to reduce the water reactivity and promote the anion-enriched structure in the electrolyte, which can efficiently suppress the byproducts and dendrite formation. These occurs thanks to the formation of an anion-derived, robust solid electrolyte interphase with an inorganic/organic hybrid structure. Such an electrolyte enables a long cycle life over 2000 h in the Zn||Zn cell and a high Coulombic efficiency of >99.5% for 700 cycles in the Zn||Ti cell. Therefore, both Zn||Na3V2(PO4)3 batteries and Zn||activated carbon capacitors in this electrolyte exhibit improved cycling performance.

Anti-inflammatory, analgesic and antitubercular activity of 4,6-diphenyl-4,5,6,7-tetrahydro-3-selena-1,2,5-triazo-indene derivatives

Several 4,6-diphenyl-4,5,6,7-tetrahydro-3-selena-1,2,5-triazo-indene derivatives have been synthesized by the Mannich reaction (condensation) of ethyl methyl ketone, substituted aldehyde and ammonium acetate and selenium dioxide. The chemical structures have been confirmed by means of IR, 1H NMR and mass spectral data. The synthesized compounds have been evaluated for anti-inflammatory, analgesic and antitubercular activity. The compounds have emerged as the most promising active compounds to that of standards. In addition, the inhibition effect increases with the increase in concentration of these compounds.

Constructing Additives Synergy Strategy to Doctor-Blade Efficient CH3 NH3 PbI3 Perovskite Solar Cells under a Wide Range of Humidity from 45% to 82.

Perovskite solar cells (PSCs) have emerged as one of the most promising and competitive photovoltaic technologies, and doctor-blading is a facile and robust deposition technique to efficiently fabricate PSCs in large scale, especially matching with roll-to-roll process. Herein, it demonstrates the encouraging results of one-step, antisolvent-free doctor-bladed methylammonium lead iodide (CH3 NH3 PbI3, MAPbI3 ) PSCs under a wide range of humidity from 45% to 82%. A synergy strategy of ionic-liquid methylammonium acetate (MAAc) and molecular phenylurea additives is developed to modulate the morphology and crystallization process of MAPbI3 perovskite film, leading to high-quality MAPbI3 perovskite film with large-size crystal, low defect density, and ultrasmooth surface. Impressive power conversion efficiency (PCE) of 20.34% is achieved for doctor-bladed PSCs under the humidity over 80% with a device structure of ITO/SnO2 /MAPbI3 /Spiro-OMeTAD/Ag. It is the highest PCEs for one-step solution-processed MAPbI3 PSCs without antisolvent assistance. The research provides a facile and robust large-scale deposition technique to fabricate highly efficient and stable PSCs under a wide range of humidity, even with the humidity over 80%.

Bidirectional Anions Gathering Strategy Afford Efficient Mixed PbSn Perovskite Solar Cells.

Mixed lead-tin (PbSn) perovskite solar cells (PSCs) possess low toxicity and adjustable bandgap for both single-junction and all-perovskite tandem solar cells. However, the performance of mixed PbSn PSCs still lags behind the theoretical efficiency. The uncontrollable crystallization and the resulting structural defect are important reasons. Here, the bidirectional anions gathering strategy (BAG) is reported by using Methylammonium acetate (MAAc) and Methylammonium thiocyanate (MASCN) as perovskite bulk additives, which Ac- escapes from the perovskite film top surface while SCN- gathers at the perovskite film bottom in the crystallization process. After the optoelectronic techniques, the bidirectional anions movement caused by the top-down gradient crystallization is demonstrated. The layer-by-layer crystallization can collect anions in the next layer and gather at the broader, enabling a controllable crystallization process, thus getting a high-quality perovskite film with better phase crystallinity and lower defect concentration. As a result, PSCs treated by the BAG strategy exhibit outstanding photovoltaic and electroluminescent performance with a champion efficiency of 22.14%. Additionally, it demonstrates excellent long-term stability, which retains ≈92.8% of its initial efficiency after 4000 h aging test in the N2 glove box.

Stabilization of Perovskite Lattice and Suppression of Sn2+/Sn4+ Oxidation via Formamidine Acetate for High Efficiency Tin Perovskite Solar Cells

AbstractTin halide lead‐free perovskite solar cells (TPSCs) have received tremendous research interest recently due to their nearly ideal bandgap, broad light absorption, non‐toxicity, and environmental friendliness. However, the uncontrollable crystallization process and the facile oxidation of Sn2+ limit the further increase of power conversion efficiency (PCE). To solve these problems, a series of acetates are introduced into the perovskite precursor solution to regulate the crystallization process. It is revealed that formamidine acetate (FAAc) has strong COSn coordination with Sn2+ compared with acetic acid (HAc) and methylammonium acetate (MAAc), which can stabilize the lattice structure, minimize defect states and suppress the oxidation of Sn2+. Meanwhile, benefiting from this coordination ability, it not only leads to large‐size colloidal clusters in precursor but also slows down the crystallization process and improves the crystallinity of tin halide perovskite films. The device with FAAc achieved an increased PCE from initially 9.84% to 12.43%, and it could maintain 94% of its initial value for 2000 h in N2 atmosphere. This work provides a feasible strategy for depositing high‐quality tin perovskite films with low defect density and lattice distortion, which will be crucial for related photovoltaics and other optoelectronic devices.

Dual Sub‐Cells Modification Enables High‐Efficiency n–i–p Type Monolithic Perovskite/Organic Tandem Solar Cells

AbstractMonolithic perovskite/organic tandem solar cells (POTSCs) have attracted increasing attention owing to ability to overcome the Shockley–Queisser limit. However, compromised sub‐cells performance limits the tandem device performance, and the power conversion efficiency (PCE) of POTSCs is still lower than their single‐junction counterparts. Therefore, optimized sub‐cells with minimal energy loss are desired for producing high‐efficiency POTSCs. In this study, an ionic liquid, methylammonium acetate (MAAc), is used to modify wide‐bandgap perovskite sub‐cells (WPSCs), and bathocuproine (BCP) is used to modify small‐bandgap organic solar cells. The Ac− group of MAAc can effectively heal the Pb defects in the all‐inorganic perovskite film, which enables a high PCE of 17.16% and an open‐circuit voltage (Voc) of 1.31 V for CsPbI2.2Br0.8‐based WPSCs. Meanwhile, the BCP film, inserted at the ZnO/organic bulk‐heterojunction (BHJ) interface, acts as a space layer to prevent direct contact between ZnO and the BHJ while passivating the surface defects of ZnO, thereby mitigating ZnO defect‐induced efficiency loss. As a result, PM6:CH1007‐based SOSCs exhibit a PCE of 15.46%. Integrating these modified sub‐cells enable the fabrication of monolithic n–i–p structured POTSCs with a maximum PCE of 22.43% (21.42% certified), which is one of the highest efficiencies in such type of POTSCs.

Perovskite solar cells based on screen-printed thin films.

One potential advantage of perovskite solar cells (PSCs) is the ability to solution process the precursors and deposit films from solution1,2. At present, spin coating, blade coating, spray coating, inkjet printing and slot-die printing have been investigated to deposit hybrid perovskite thin films3-6. Here we expand the range of deposition methods to include screen-printing, enabled by a stable and viscosity-adjustable (40-44,000 cP) perovskite ink made from a methylammonium acetate ionic liquid solvent. We demonstrate control over perovskite thin-film thickness (from about 120 nm to about 1,200 nm), area (from 0.5 × 0.5 cm2 to 5 × 5 cm2) and patterning on different substrates. Printing rates in excess of 20 cm s-1 and close to 100% ink use were achieved. Using this deposition method in ambient air and regardless of humidity, we obtained the best efficiencies of 20.52% (0.05 cm2) and 18.12% (1 cm2) compared with 20.13% and 12.52%, respectively, for the spin-coated thin films in normal devices with thermally evaporated metal electrodes. Most notably, fully screen-printing devices with a single machine in ambient air have been successfully explored. The corresponding photovoltaic cells exhibit high efficiencies of 14.98%, 13.53% and 11.80% on 0.05-cm2, 1.00-cm2 and 16.37-cm2 (small-module) areas, respectively, along with 96.75% of the initial efficiency retained over 300 h of operation at maximum power point.

The Role of Ionic Liquids in Performance Enhancement of Two‐Step Perovskite Photovoltaics

Much of the research efforts of late that are directed toward enhancement of the efficiency of perovskite‐based photovoltaics are focused on the application of ionic liquids (ILs) in a one‐step approach. On the contrary, the details of the alternative two‐step approach, such as the role of the ILs in the perovskite film solidification and its optoelectronic properties, remain poorly understood despite the increasing evidence that this latter method might offer considerable advantages, including better reproducibility and control over crystallization. Herein, the effect of IL methylammonium acetate (MAAc) introduced into the PbI2 layer by a sequential deposition process on the optoelectronic properties of the perovskite film and the performance of the ensuing photovoltaic devices are studied. The addition of MAAc lowers the MAAc–perovskite formation enthalpy, leading to an accelerated solidification process. Moreover, MAAc suppresses the formation of Pb0, thereby facilitating the perovskite formation while lowering the deep defect states caused by Pb0. In addition to grain boundary passivation, the acetate ions can diffuse into the bulk of the perovskite material, filling up the halide vacancies with reduced trap state density. As a result, a decent power conversion efficiency of 23.36% is achieved, with noticeably improved durability.

Methyl 5-Imino-2-methyl-1,10a-dihydro-5H-chromeno[2,3-b]pyridine-3-carboxylate

Multicomponent reactions are valuable synthetic tools to deliver highly functionalized motifs starting from simple building blocks in only one step and in an atom-economical way. Herein we disclose the structure of a new and unexpected compound, the methyl 5-imino-2-methyl-1,10a-dihydro-5H-chromeno[2,3-b]pyridine-3-carboxylate, which was formed in the ohmic-heating-assisted multicomponent Hantzsch reaction of 3-formylchromone with methyl acetoacetate and ammonium acetate, in aqueous medium, in the presence of tetrabutylammonium bromide as phase transfer catalyst. The title compound was isolated with no need of chromatographic separation and was analyzed by nuclear magnetic resonance (1H and 13C-NMR, HSQC and HMBC) spectroscopy, mass spectrometry (MS) and high-resolution mass spectrometry (HRMS). Its formation as the main reaction product was observed when the reaction was performed using ohmic heating, which may lead to some speculations about the possible existence of specific effects of ohmic heating in the reactivity pathway because of the passage of an alternating electric current of high frequency within the reaction media, opening new opportunities for further investigations of the potential of this thermal processing method in organic synthesis and reactivity optimization.

Achieving Low Threshold and High Optical Gain Amplified Spontaneous Emission in MAPbI3 Perovskite Films via Symmetric Waveguide Effect

AbstractLead halide perovskites are attractive light source candidates for new amplifiers and lasers in the growing field of short‐distance data communication. However, the presence of plenty of defects and poor stability are the major obstacle to the production and application of perovskite optoelectronic devices. Three strategies are proposed to prepare MAPbI3 perovskite films with high stability and enhanced light amplification in this study: 1) MAPbI3 films are prepared with ionic liquid methylammonium acetate (MAAc) to improve the quality of the films; 2) a poly(methyl methacrylate) (PMMA) passivation layer is used to improve the optical and thermal stability of the MAPbI3 film; 3) a symmetric waveguide (SWG) structure is designed to enhance the amplified spontaneous emission (ASE) properties of the MAPbI3 film. The formed SWG exhibits increased mode confinement and reduced propagation loss, thus enabling a lower ASE threshold, a higher optical gain and improved photostability, thermal and humidity stability compared with the pristine MAPbI3 film. Femtosecond transient absorption spectroscopy and electric field distribution calculation are utilized to elucidate the carrier dynamics and carrier‐phonon effect and the microscopic origin of the observed effects of functionalization. This study indicates the possibility of simple and effective approaches for realizing efficient ASE and lasing.

Effect of Ionic Liquid Methylammonium Acetate on the Performance of Hole-Transport Material-Free Mesoporous Perovskite Solar Cells with Carbon Electrode

Effect of Ionic Liquid Methylammonium Acetate on the Performance of Hole-Transport Material-Free Mesoporous Perovskite Solar Cells with Carbon Electrode

Improving the Air Resistance of the Precursor Solution for Ambient-Air Coating of an Sn-Pb Perovskite Film with Superior Photovoltaic Performance.

Owing to narrow band gap and low toxicity, tin-lead (Sn-Pb) hybrid perovskites have shown great potential in photovoltaic applications, and the highest power conversion efficiency (PCE) of Sn-Pb perovskite solar cells (PSCs) has recently reached 23.6%. However, it is still challenging to prepare Sn-Pb films in open-air condition due to the Sn2+ oxidation of the precursor solution under this condition. In this work, we report the stabilizing of the Sn-Pb perovskite precursor solution by using ionic liquid methylammonium acetate (MAAc) as the solvent, which enables the fabrication of Sn-Pb films in air. MAAc is found to coordinate with the Sn-Pb precursor via abundant hydrogen bonding, which stabilizes the colloids and protects the Sn2+ stability in the precursor solution in air. Therefore, the durability of the Sn-Pb precursor solution based on the MAAc solvent is greatly improved, which enables the fabrication of efficient PSCs and achieves a champion PCE of ∼16% with robust device stability. Moreover, due to the chemical interactions of MAAc with Sn-Pb perovskites, the Pb leakage is also suppressed in the MAAc-based Sn-Pb PSCs. This work demonstrates a feasible strategy for reliable fabrication of Sn-Pb PSCs, which could also be applied in many other optoelectronic devices.

Pin-hole free MAPb0.75 Sn0.25 (I0.5 Br0.5 ) 3 films spin casted without anti- solvent by adding MAAc additive to perovskite ink

To start the crystallization of the tin (Sn) based perovskite materials, anti-solvent treatment is a useful technique. But the use of anti-solvents increases the complexity of the deposition process thus hinders the applicability in mass production processes. Here we have developed an anti-solvent free MAPb0.75Sn0.25(I0.50Br0.50)3 perovskite thin film deposition method based on a one step spin coating process. Addition of 0 - 100 mol% of methylammonium acetate (MAAc) to the precursor ink allows for the deposition of continuous films. Films casted from ink with less than 60 mol% MAAc show pinholes and are rough. A decent crystalline and pin-hole free perovskite thin film can be obtained from 60 or more mol% MAAc additive. These results are confirmed by XRD, AFM and SEM measurements. MAPb0.75Sn0.25(I0.50Br0.50)3 has a wide bandgap and is currently being considered for applications in tandem solar cells and under water solar cells.

Direct and stable α-phase formation via ionic liquid solvation for formamidinium-based perovskite solar cells

<h2>Summary</h2> Direct and stable α-phase formation of formamidinium lead triiodide (FAPbI₃) perovskite serves as an indispensable prerequisite for constructing stable and efficient perovskite solar cells. However, the α-phase formation is highly limited by molecular additives. Here, we report a strategy for directly fabricating stable α-phase of FAPbI₃ perovskite by controlling the precursor solution on the molecular level using methylammonium acetate (MAAc) ionic liquid. We found that a strong interaction between Ac⁻ and Pb²⁺ via C=O···Pb chelation enables the relaxation of Pb–I bonds and thus allows the effective insertion of formamidinium iodide (FAI) into soft Pb–I framework. Molecular dynamics simulations also show that the precursor solution has undergone an exchange of coordination between I⁻ and Ac⁻ to provide the reaction sites for FAI. With a one-step, antisolvent-treatment-free, and air-processing approach regardless of humidity, the corresponding photovoltaic cell exhibits an efficiency close to 24% along with long operational stability over 1,000 h.