Hybrid Organic-inorganic Halide Perovskites Research Articles

A Lead-Free Ferroelectric 2D Dion-Jacobson Tin Iodide Perovskite.

2D hybrid organic-inorganic halide perovskites emerge as a new class of 2D semiconductors with the potential to combine excellent optoelectronic properties with symmetry-enabled properties such as ferroelectricity. Although many lead-based ferroelectric 2D halide perovskites are reported, there is yet to be a conclusive report of ferroelectricity in tin-based 2D perovskites. Here, the structures and properties of a new series of 2D Dion-Jacobson (DJ) Sn perovskites: (4AMP)SnI4, (4AMP)(MA)Sn2I7, and (4AMP)(FA)Sn2I7 (4AMP = 4-(aminomethyl)piperidinium, MA = methylammonium, and FA = formamidinium), are reported. Structural characterization reveals that (4AMP)SnI4 is polar with in-plane spontaneous polarization whereas (4AMP)(MA)Sn2I7 and (4AMP)(FA)Sn2I7 are centrosymmetric. Further, (4AMP)SnI4 displays second harmonic generation (SHG) and polarization-electric field hysteresis measurements confirm it is ferroelectric with a spontaneous polarization of 10.0 µC cm-2 at room temperature. (4AMP)SnI4 transitions into a centrosymmetric structure above 367 K. As the first direct experimental observation of the spontaneous ferroelectric polarization of a Sn-based 2D hybrid perovskite, this work opens up environmentally friendly 2D tin halide perovskites for ferroelectricity and other physical property studies.

Optimizing the depletion width to enhance the performance of CH3NH3PbI3 flexible photodetector based on the piezo-phototronic effect

The research on organic-inorganic hybrid halide perovskites in the field of optoelectronics has greatly advanced the field of photodetection. However, the reported heterojunction structure of perovskite results in complex preparation processes. A simple method was designed to enhance the performance of CH3NH3PbI3 flexible photodetector (PD) by optimizing the depletion width based on the piezo-phototronic effect. Under 5 V bias conditions, when the electrode width of PD is 3, 5, and 8 μm, where the response peaks at 760 nm are 0.06, 0.02, and 0.01 A/W, respectively. This depends on the decrease of electrode width and the increase of depletion width. As the strain increases, the PD response of the interdigital electrode at 3 μm increases from 0.020 to 0.0482 A/W. When the strain is 0.3, the responsiveness increases by 240 %. As the strain increases, the PD response of the interdigital electrode at 5 μm increases from 0.010 to 0.0255 A/W and the PD response of the interdigital electrode at 8 μm increases from 0.006 to 0.0137 A/W. Therefore, devices with a wide depletion width have significant performance advantages. This work improves the responsivity of perovskite flexible PD based on the piezo-phototronic effect by optimizing the depletion width, providing a simple and effective method for manufacturing perovskite thin film devices on high-performance flexible substrates.

Ab-initio study of hybrid perovskites Cs2AgGaCl6 for solar cells applications

Double perovskites have garnered significant attention for use in renewable energy applications, particularly solar cells. The development of organic-inorganic hybrid halide perovskite solar cells has advanced rapidly over the last ten years. In this article, fundamental aspects of transport properties of Cs2AgGaCl6 have been illustrated using DFT-based simulation. Constantly is covered that the calculated lattice constant agreed with the available experimental data. With an indirect band gap, the electronic profile demonstrates a semiconducting nature. Reporting bandgap of 1.20 eV for Cs2AgGaCl6. This bandgap remains suitable for solar cell semiconductors. The computed values of effective masses reveal that effective masses of holes are greater than those of electrons. Further various optical parameters have also been examined. The absorption of light in the visible and ultraviolet spectrums is guaranteed by the absorption bands 2.7–4.2 eV and 3.5–4.5 eV. We believe that such insights offer a new starting point and a framework for future research. So, knowledge and drive gained from these studies will stimulate more theoretical investigation into novel perovskite-based materials with novel applications.

Two-dimensional lead halide perovskite lateral homojunctions enabled by phase pinning

Two-dimensional organic-inorganic hybrid halide perovskites possess diverse structural polymorphs with versatile physical properties, which can be controlled by order-disorder transition of the spacer cation, making them attractive for constructing semiconductor homojunctions. Here, we demonstrate a space-cation-dopant-induced phase stabilization approach to creating a lateral homojunction composed of ordered and disordered phases within a two-dimensional perovskite. By doping a small quantity of pentylammonium into (butylammonium)2PbI4 or vice versa, we effectively suppress the ordering transition of the spacer cation and the associated out-of-plane octahedral tilting in the inorganic framework, resulting in phase pining of the disordered phase when decreasing temperature or increasing pressure. This enables epitaxial growth of a two-dimensional perovskite homojunction with tunable optical properties under temperature and pressure stimuli, as well as directional exciton diffusion across the interface. Our results demonstrate a previously unexplored strategy for constructing two-dimensional perovskite heterostructures by thermodynamic tuning and spacer cation doping.

Insights into the effect of methylammonium orientation on the crystal structural, electronic structure and optical properties of CH3NH3SnI3

Organic-inorganic hybrid halide perovskites have become an important new generation solar cell materials that are expected to significantly improve the solar conversion efficiency. In this work, the effect of methylammonium (CH3NH3) orientation on CH3NH3SnI3 perovskite is studied by using the first principles of density functional theory. We report the electronic and optical properties of methylammonium in different orientations. It is shown that CH3NH3 orientation leads to an increase in the absorption coefficient and complex refractive index of the material, a redshift in the absorption spectrum, and an enhanced absorption in the visible and near-infrared regions. We find that these changes are strongly influenced by organic-inorganic interactions and octahedral distortions. It suggests that the band gap and optical properties may be effectively modulated by the CH3NH3 rotation orientation, providing valuable insights into the behavior of CH3NH3 embedded in the inorganic octahedra of experiments.

Cognitively Driven Autonomous Flow Chemistry for Producing On-Demand Perovskite Quantum Dots Via Advanced Closed-Loop Feedback Control.

Recent developments in the synthesis of hybrid organic-inorganic halide perovskite quantum dots (HP-QDs) through compositional adjustments have highlighted their potential applications in the fields of photovoltaics and light sources due to their unique optoelectronic properties. However, traditional methods to fine-tune their composition involve repetitive, labor-intensive, and costly processes. Herein, the utilization of a continuous flow chemistry approach is developed, in combination with a Proportional-Integral (PI) feedback control system as an effective method for producing on-demand methylammonium lead bromoiodide (MAPbBrx I3-x ) HP-QDs. The PI feedback control allows for real-time optimization of the flow rates of halide precursor solutions (halide PSs), enabling the precise tuning of the emission wavelength of HP-QDs. HP-QDs having an emission wavelength of 550 and 650nm are synthesized through a blue-shifted and red-shifted algorithm, respectively, from any arbitrary reaction condition within 400 s. The iterative process through the PI feedback control produces the target HP-QDs with short rise time and low overshoot. The proposed automatic flow chemistry system integrated with a universal and accessible control algorithm of PI can generate the target HP-QDs with high accuracy, stability, and robustness, demonstrating a significant advancement in constructing an autonomous flow chemistry synthetic system.

Novel One-Dimensional Organic–Inorganic Hybrid Halide Perovskite Material with Coexistence of High Phase Transition Temperature and Corresponding Dielectric Response

Novel One-Dimensional Organic–Inorganic Hybrid Halide Perovskite Material with Coexistence of High Phase Transition Temperature and Corresponding Dielectric Response

(Invited) Efficient and Stable Perovskite Solar Cells Enabled By Surface Engineering with Bulky Organic Molecules

Organic-inorganic hybrid halide perovskites have attracted significant R&D attention in the photovoltaic (PV) community as a competitive technology for future PV applications. The certified efficiency of single-junction perovskite solar cell (PSC) has reached close to 26%. Using molecules/structures based on bulky organic cations (e.g., butylammonium or phenethylammonium) to improve the surface/interface properties has become a promising strategy to enhance PSC performance, including both efficiency and stability. However, significant issues still exist with the use of bulky organic molecules, such as structure control, charge transport, bulk and surface morphology, and interfacial energy alignment. In this talk, I will discuss our recent studies on surface engineering of 3D perovskites by using structures based on bulky organic molecules. The use of bulky organic molecules often results in the formation of 2D perovskite structures, which usually exhibit significant transport barriers, especially in the out-of-plane transport direction. In addition, the use of bulky organic structures can interrupt the growth of 3D perovskites. A good understanding and control of perovskite growth is critical to fully utilize the benefits associated with bulky organic molecules and related structures. I will present strategies for suppressing defect formation, improving bulk and surface morphology, and reducing transport barrier for better extraction. The physical and optoelectronic properties of perovskites can be affected by controlling the precursor chemistry and growth conditions. Some of our recent results on perovskite-based tandem devices will also be discussed. Finally, I will discuss our recent progress on selecting stability protocols to accelerate the development process of PSCs toward future commercialization.

Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells.

Organic-inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10-5 S cm-1 upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10-6 S cm-1) while only costing an estimated $5/g. We ascribe the increased optoelectronic properties to favorable molecular packing, as shown by single-crystal X-ray diffraction, which results in close spacing between the triphenylamine blocks. This, in turn, results in a short hole-hopping distance between molecules and therefore good mobility and conductivity. In addition, TPABT exhibits a higher bandgap and is as a result more transparent in the visible range of the solar spectrum, leading to lower parasitic absorption losses than Spiro-OMeTAD, and has increased moisture stability. We applied the molecule in perovskite solar cells and obtained good efficiency values in the ∼15% range. Our approach shows that engineering better molecular packing may be the key to developing high-efficiency, low-cost HTMs for perovskite solar cells.

A first‐principles investigation into the rational design of Sn‐halide perovskite materials as an alternative to Pb‐based perovskites

AbstractThe development of Pb‐free alternatives for perovskite‐based photovoltaics is extremely important due to the toxicity of Pb to the environment. Sn‐based organic inorganic hybrid halide perovskites are considered to be the most suitable alternative to Pb‐based ABX perovskites due to their similar optoelectronic properties. The selection of A site cation in ABX type perovskites is crucial for favorable structural and mechanical properties. Using first principle methods, we have designed and investigated Sn–I based hybrid halide perovskite materials with different organic cations mixed in equal proportions. Observed tolerance (TF) and octahedral factors () indicate the formation of stable three‐dimensional perovskite structure. Our studied materials also exhibit thermodynamic stability due to the negative value of their formation energies. Observed band gap values indicate the semiconducting nature of our studied perovskite materials. Calculated optical properties indicate that all of the compounds exhibit suitable dielectric functions and absorption coefficients in the visible range of the electromagnetic spectrum. The observed highest value of theoretical power conversion efficiency of MA‐AMSnI (11.24%) indicates its potential to be used in photovoltaics. Our investigation will be beneficial for researchers to develop less toxic and efficient perovskite materials for the fabrication of optoelectronic devices.

Dimension-Controlled Synthesis of Hybrid-Mixed Halide Perovskites for Solar Cell Application.

Despite the rapid improvement of photovoltaic (PV) efficiency in hybrid organic-inorganic metal halide perovskites (HOIPs), the fabrication procedure of a compact thin film in a large-area application is still a tedious work. Apart from the quality of the thin film, the stability of the perovskite materials and the expensive organic hole transport layer (HTL) within the HOIP-based PV device are the major issues that need to be addressed prior to their commercialization. Herein, a unique glass rod-based facile fabrication technique for producing a compact and stable thin film utilizing a mixed-halide-based perovskite precursor solution is demonstrated. The fabricated devices deliver high photoconversion efficiency (PCE) without the use of any HTL and show an excellent stability under ambient conditions. By varying the organic CH3NH3I (MAI) and inorganic PbBr2 content, perovskite materials with different dimensions, i.e., 3D, 2D, and 1D, are synthesized to produce an active layer for PV devices. Although a 2D single-halide perovskite is reported earlier, herein two different mixed-halide 2D perovskites, i.e., MA2PbI2Br2 and MAPb2IBr4, are synthesized successfully, and their performance is compared in detail along with that of 1D and 3D mixed-halide perovskites. The facile synthesized mixed-halide 2D-based MA2PbI2Br2 perovskite shows a PCE of 10.14% with a high stability of 92% after 100 days without encapsulation, which is much superior as compared to that of the mixed-halide 3D MAPbIBr2. The semiconducting behavior as well as the nature of the bandgap of the synthesized compounds is examined by pursuing density functional theory calculations. Specifically, the role of iodine doping to modify the electronic band structure is investigated, and introduction of iodine is found to reduce the effective masses of both electrons and holes in the perovskite material.

Efficient and stable Sn based perovskite solar cells by the modulation of crystallization with bulky organic cation for large nucleation cluster

Organic-inorganic hybrid halide perovskite have been attracting much attention as promising photovoltaic materials owing to their exceptional photovoltaic characteristics. However, even though the rise of progress for the perovskite solar cell was increased, it was still remained the concern for the toxicity of lead in hybrid organolead based perovskite solar cell, which is the harmful materials to the environmental system.Herein, we incorpoarted the homopiperazium (HP2+) into the FASnI3 perovskite to prepare a high-quality perovskite film with a lower defect density. Since the HP is the largest organic cation, that can not enter 3D perovskite but it played a significant role in modulating the crystallinity, morphology and optoelectronic properties of FASnI3 perovskite. When the HPI2 introduced the perovskite precursor solution, it affects the nucleation of perovskite solution by the formation of large pre-nulceation cluster through the linked colloids. It decrease the energy barrier, resulting in a high-quality perovskite film with a lower defect density. Highly oriented perovskite film exhibits the PCE up to a high at 6.88%, with high long-term stability as well which is much higher than that of the pristine FASnI3 perovskite film (4.71%).

Bandgap prediction of ABX3-type perovskites using Broad Learning System

Perovskite materials have attracted significant attention of scholars at home and abroad due to their excellent photoelectric properties, with the bandgap being a crucial factor that directly determines the performance of perovskite solar cells. However, density functional theory (DFT) calculations of bandgap are time-consuming and costly. To address this issue, Broad learning System (BLS), a data-driven machine learning algorithm, is proposed to predict the bandgap of hybrid organic-inorganic halide perovskites using a dataset of 227 ABX3-type perovskites with experimental bandgap values, and the stoichiometric ratio of positions A, B, X of perovskite as input features. The results demonstrate that BLS algorithm provides superior predictions compared to Support Vector Regression (SVR), Multi-Layer Perceptron (MLP) and Random Forest (RF). BLS algorithm has a lower root mean square error (RMSE), and a higher correlation coefficient (R2), with RMSE being 0.0855 eV and R2 reaching 92.24 %. This work indicates that BLS can be a powerful and potential tool for predicting the bandgap of perovskites.

Development of MnxCo0.015Zn1-xO electron transport layer for perovskite solar cells: Experimental and simulation study

The electron transport layer (ETL) plays an important role in the performance and stability enhancement of perovskite solar cells (PSCs). Zinc oxide is considered a cost-effective and low-temperature processed ETL for PSCs, which offers decent mobility. However, the interface reaction occurs via a reaction of zinc oxide with the organic-inorganic metal hybrid halide perovskite absorber, which results in the degradation of the PSCs. To overcome this issue, metal doping was carried out. However, metal doping causes a reduction in the transmittance of the zinc oxide ETL layer because of high absorption. Thus, the overall performance of the PSCs was reduced due to the lessening of the photogenerated current. In this regard metal co-doping (Mn and Co) was done to improve the electrical as well as electronic properties. Furthermore, the influence of Mn doping on the structural, optical, and photoluminescence properties of MnxCo0.015Zn1-xO (x = 0, 0.002, 0.008, and 0.012) hexagonal nanosheets was investigated. X-ray diffraction results revealed that the inter-planar spacing, cell parameters, unit cell volume, lattice strain, and dislocation density were maximum for the Mn content of 0.2%. The acquired values of the optical band gap (Eg) are 3.39, 3.52, 3.58, and 3.18 eV for x = 0, 0.2%, 0.8%, and 1.2%, respectively. The corresponding absorption coefficient is reduced with increasing Mn content. The obtained refractive indices are 1.437, 1.402, 1.428, and 1.426 for x = 0, 0.2, 0.8, and 1.2%, respectively. The above results confirm that the MnxCo0.015Zn1-xO with x = 0.8% provides the lowest absorption and the highest value of bandgap. Thus, it can be the most suitable ETL for high-performance PSCs. The simulation results reveal that via applying MCZO ETL, the efficiency can be achieved over 23%.

Tungsten dopant incorporation for bandgap and type engineering of perovskite crystals

Organic–inorganic hybrid halide perovskites have shown to be viable semiconductor materials, as the absorber layer of solar cells. Unfortunately, the polycrystalline qualities of perovskite films result in nonuniform coverage or a high recombination rate, which weakens the photoelectric capabilities of thin films. Here, the pure and tungsten (W)-doped methylammonium lead bromide (CH3NH3PbBr3 or MAPbBr3) films are deposited to FTO-glass substrates using the sol–gel spin coating method. The W-doping causes the nucleation and crystallization processes, which then have an impact on the film’s characteristics. It is discovered that the introduction of tungsten metal significantly enhances the quality of the perovskite film, resulting in larger grain sizes, lower band gap energy, and shorter recombination lifetimes, increasing the power conversion efficiency of perovskite thin film solar cells.

Synthesis and characterization of mehtylammonium bismuth iodide via solvent engineering

Hybrid organic–inorganic halide perovskites (OIHPs) are an emerging class of photovoltaic materials that have gained tremendous attention in the field of optoelectronics. This work aims to investigate the characteristics of bismuth-based halide perovskite via solvent engineering for solar cell application. A bismuth-based organo-inorganic perovskite was synthesized and characterized for solar cell application via solvent engineering using Gamma Butyrolactone (GBL) as the based solvent and enhanced with Methylamine (MA) and acetonitrile (ACN). A solution processing facile method was adopted in the synthesis of the perovskite. The solvent engineering aims to tune its band gap and a remarkable band gap of 1.58eV which is within the range of an ideal band gap (1.5-1.6) required for solar cell application. The XRD micrograph exhibited several narrow sharp peaks which indicated crystallinity formation of the synthesized sample with 86% crystallinity. The FESEM/EDS micrograph indicated nature of the formed crystals and the chemical composition of the sample. A multilayer heptagonal crystal was observed. The TGA result showed that the sample is thermally stable at a temperature of 200oC before degradation occurred.

Recent progress and rational design of perovskite-based chemosensors: A review

In the past decades, perovskite-based materials have demonstrated excellent performances in a wide range of applications, including chemosensing. Owing to their unique structure-property relationship, chemosensing applications have become a point of interest that intrigued researchers from various backgrounds. Recently, several studies have reported the application of perovskite in chemosensing using various methods and analytes. However, the development for stable, sensitive, and selective chemosensors requires multiple approaches and considerations. In this review, the recent progress on perovskite-based chemosensor is summarized, with regards to different sensing mechanisms and target analytes subject to detection. Several aspects and fundamental factors affecting the chemosensor designs are also briefly discussed. In addition to the type of perovskites (including oxide, all inorganic halide, and hybrid organic-inorganic halide perovskites), perovskite design should also consider the structural dimensionality as an important factor that influenced the chemical and physical properties of the materials. We describe the upcoming challenges and limitations that could potentially be encountered in the development of perovskite chemosensors to provide some potential solutions and outlook. The future prospect of perovskite-based chemosensors is expected to rise due to continued interests and attention, which might pave the way for the advancement of innovative sensing technology.

Density Functional Theory Insights into the Structural, Electronic, Optical, Surface, and Band Alignment Properties of BaZrS3 Chalcogenide Perovskite for Photovoltaics

Chalcogenide perovskites (CPs) have recently emerged as attractive thermally and chemically stable candidates to overcome the inherent instability and toxicity issues of the conventional hybrid organic–inorganic halide perovskites (OIHPs). However, before further progress can be made in CP thin-film photovoltaic (PV) cells, there is a need to gain fundamental insights into their bulk, surface, and interfacial properties. Herein, we employed density functional theory (DFT) calculations to systematically characterize the bulk (structural, electronic, and optical), surface (compositions, relative stabilities, crystal morphology, and work function), and interfacial (energy band alignment) properties of BaZrS3, one of the most promising members of the CP family. BaZrS3 is found to exhibit a direct bandgap of 1.74 eV with small photocarrier effective masses, high absorption coefficient (∼105 cm–1), low reflectivity (22%), and low refractive index (2.75), all of which are desirable characteristics for efficient PV applications. Comprehensive analyses of the structures, compositions, and relative stabilities of the low-Miller-index surfaces of BaZrS3 revealed that the (010), (100), and (111) surfaces are the most stable surfaces, which are also largely expressed in the Wulff-constructed equilibrium crystal morphology of BaZrS3. Based on the computed ionization potential (IP) and electron affinity (EA), we have constructed a vacuum-aligned energy band diagram of BaZrS3 with commonly used hole- and electron-transport materials (HTMs and ETMs, respectively). CuI (HTM) and CdS (ETM) are predicted as the best heterojunction materials to form favorable alignment (staggered type II) with optimum band offsets with the BaZrS3(111) surface for efficient charge-carrier separation and improved solar cell performance. Our results show great promise for developing more efficient and stable BaZrS3-based chalcogenide perovskite solar cells.

Taming Friedrich–Wintgen Interference in a Resonant Metasurface: Vortex Laser Emitting at an On-Demand Tilted Angle

Friedrich-Wintgen (FW) interference is an atypical coupling mechanism that grants loss exchange between leaky resonances in non-Hermitian classical and quantum systems. Intriguingly, such a mechanism makes destructive interference possible for scenarios in which a radiating wave becomes a bound state in the continuum (BIC) by giving away all of its losses. Here we propose and demonstrate experimentally an original concept to tailor FW-BICs with polarization singularity at on-demand wavevectors in an optical metasurface. As a proof-of-concept, using hybrid organic-inorganic halide perovskite as an active material, we empower this novel polarization singularity to obtain lasing emission, exhibiting both highly directional emission at oblique angles and a polarization vortex in momentum space. Our results pave the way to steerable coherent emission with a tailored polarization pattern for applications in optical communication/manipulation in free space, high-resolution imaging/focusing, and data storage.

Synthesizing and characterization of Lead Halide Perovskite Nanocrystals solar cells from reused car batteries

With the rapid increase of efficiency up to 23.7% during the past few years, hybrid organic-inorganic metal halide perovskite solar cells (PSCs) have become a research “hot spot” for many solar cell researchers. The perovskite materials show various advantages due to unique characteristics of perovskite materials, such as high photo-to-electric conversion efficiency, direct band gap, high light absorption coefficient, high charge-carrier mobility and long electron-hole electron transport distance. The low-cost fabrication techniques together with the high efficiency makes PSCs comparable with Si-based solar cells. This paper begins with the discussion of crystal structures of perovskite based on recent research findings. The following part of this paper discussion of synthetic process of lead iodide perovskite materials from lead-acid battery and Harvesting material from the anodes and cathodes of car battery; synthesizing PbI2 from the collected materials and compare with pure Lead iodide to know the absolute by XRD peak, depositing lead iodide perovskite nanocrystals. Efficient flexible PSCs are fabricated onto FTO glass substrate by a two-step coating method under ambient condition. By adjusting the concentration of precursor CH3NH3I (MAI), the morphology and thickness of perovskite layer is effectively tailored, according to SEM analysis and using TiO2 as electron transport layer instead of ZnO and CuI instead of spiro-OMeTAD as hole transport layer.