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Cs/MAPbI3 composite formation and its influence on optical properties
摘要： The stability issue is very critical for organic hybrid perovskite CH3NH3PbI3 to be used in solar cell applications; whereas CsPbI3 is reported to be more stable than that of CH3NH3PbI3. In the present work, we attempt to substitute Cs+ in the organic hybrid perovskite CH3NH3PbI3 matrix to form Csx(CH3NH3)1-xPbI3 with 0 ≤ x ≤ 0.4 in ambient conditions i.e., at room temperature and in air via solid state reaction route. The structural studies reveal presence of both CH3NH3PbI3 (tetragonal, I4/mcm) and CsPbI3 (orthorhombic, Pnma) phases for x > 0. It is appearing that partial solid solution formation has occurred up to x = 0.2 but for x > 0.2, the composite formation dominates. The optical band gap is slightly increased by ~ 0.02 eV with substitution. These compounds keep the basic feature of parent CH3NH3PbI3 along with stability of CsPbI3.
关键词： Composite,Raman,Perovskite materials,XRD
更新于2025-09-23 15:23:52
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Disentangling topographic contributions to near-field scanning microwave microscopy images
摘要： We develop empirical models to predict the contribution of topographic variations in a sample to near-field scanning probe microwave microscopy (NSMM) images. In particular, we focus on |S11| images of a thin Perovskite photovoltaic material and a GaN nanowire. The difference between the measured NSMM image and this prediction is our estimate of the contribution of material property variations to the measured image. Prediction model parameters are determined from either a reference sample that is nearly free of material property variations or directly from the sample of interest. The parameters of the prediction model are determined by robust linear regression so as to minimize the effect of material property variations on results. For the case where the parameters are determined from the reference sample, the prediction is adjusted to account for instrument drift effects. Our statistical approach is fully empirical and thus complementary to current approaches based on physical models that are often overly simplistic.
关键词： Near-field scanning probe microwave microscopy,Signal extraction,GaN nanowire,Statistical methods,Perovskite materials,Atomic force microscopy
更新于2025-09-23 15:23:52
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Efficient Interconnection in Perovskite Tandem Solar Cells
摘要： Organic–inorganic hybrid perovskite materials are excellent candidates as light absorbers in tandem solar cells with advantages of tunable bandgaps, high absorption coefficients, facile fabrication processes, and low costs. Tandem devices offer a route to further improve the efficiency and reduce the cost for the solar cell practical applications. One critical challenge that limits the development of two-terminal perovskite-based tandem devices is the interconnection between two subcells. To achieve efficient interconnection in the tandem devices, it is required to simultaneously fulfill the high electrical, optical, and chemical requirements. In particular, chemical protection requirement is necessary to enable a tandem device in the case of solution-processed perovskite–perovskite tandem solar cells. In this work, recent advances of interconnection in perovskite-based two-terminal tandem solar cells are reviewed. A brief introduction to the topic is first given. The definition, functions, and requirements of interconnecting layers in two-terminal tandem devices are then discussed. Next, the insights into recent advances of interconnecting layers in two-terminal perovskite-based tandem solar cells (perovskite–perovskite, perovskite–polymer, perovskite–inorganic tandem solar cells) are further described. Finally, an outlook of the future research directions and a brief summary are drawn.
关键词： tandem devices,perovskite materials,interconnecting perovskite layers
更新于2025-09-23 15:19:57
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Emerging Conductive Atomic Force Microscopy for Metal Halide Perovskite Materials and Solar Cells
摘要： Metal halide perovskite materials, benefiting from a combination of outstanding optoelectronic properties and low-cost solution-preparation processes, show tremendous potential for optoelectronics and photovoltaics. However, the nanoscale inhomogeneities of the electronic properties of perovskite materials cause a number of difficulties, such as recombination, stability, and hysteresis, all of which seriously restrict device performance. Scanning probe microscopy, as a high-resolution imaging technique, has been widely used to connect local properties and micro-area morphologies to overall device performance. Conductive atomic force microscopy (C-AFM) can realize a real-space visualization of topography coupled with optoelectronic properties on a microscopic scale and thereby is uniquely suited to probe the local effects of perovskite materials and devices. The fundamental principles, alternative operation modes, and development of C-AFM are comprehensively reviewed, and applications in perovskite solar cells (PSCs) for electronic transport behavior, ion migration and hysteresis, ferroelectric polarization, and facet orientation investigation are discussed. A comprehensive understanding and summary of up-to-date applications in PSCs is beneficial to further fully exploit the potential of such an emerging technique, so as to provide a novel and effective approach for perovskite materials analysis.
关键词： ferroelectricity,perovskite solar cells,conductive atomic force microscopy,ion migration,perovskite materials,electronic transport behavior
更新于2025-09-19 17:13:59
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Predictions and Strategies Learned from Machine Learning to Develop High‐Performing Perovskite Solar Cells
摘要： Perovskite solar cells (PSCs) have recently received considerable attention due to the high energy conversion efficiency achieved within a few years of their inception. However, a machine learning (ML) approach to guide the development of high-performing PSCs is still lacking. In this paper ML is used to optimize material composition, develop design strategies, and predict the performance of PSCs. The ML models are developed using 333 data points selected from about 2000 peer reviewed publications. These models guide the design of new perovskite materials and the development of high-performing solar cells. Based on ML guidance, new perovskite compositions are experimentally synthesized to test the practicability of the model. The ML model also shows its ability to predict underlying physical phenomena as well as the performance of PSCs. The PSC model matches well with the theoretical prediction by the Shockley and Queisser limit, which is almost impossible for a human to find from an ensemble of data points. Moreover, strategies for developing high-performing PSCs with different bandgaps are also derived from the model. These findings show that ML is very promising not only for predicting the performance, but also for providing a deeper understanding of the physical phenomena associated with the PSCs.
关键词： perovskite solar cells,machine learning,perovskite materials,bandgap prediction
更新于2025-09-19 17:13:59
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High-brightness Perovskite Light-emitting Diodes Using a Printable Silver Micro-flake Contact
摘要： Achieving efficient devices while maintaining a high fabrication yield is a key challenge in the fabrication of solution-processed, perovskite-based light-emitting diodes (PeLEDs). In this respect, pinholes in the solution-processed perovskite layers are a major obstacle. These are usually mitigated using organic electron-conducting planarization layers. However, these organic interlayers are unstable under applied bias in air, and suffer from limited charge-carrier mobility. In this work, we present a high brightness p-i-n PeLED based on a novel blade-coated silver micro-flake (SMF) rear electrode, which allows for a low-cost and high performance nanocrystalline ZnO inorganic electron transporting layer to be used. This novel SMF contact is crucial for achieving high performance as it prevents the electrical shorting suffered when standard thermally evaporated silver rear contacts are used. The fabricated PeLEDs exhibit an excellent maximum luminance of 98000 cd/m2, a maximum current efficiency of 22.3 cd/A, and high external quantum efficiency of 4.6% under 5.9 V forward bias. The SMF rear contact can be printed and scaled at low cost to large areas and applied to flexible devices.
关键词： leakage current,light emitting diodes,nanocrystalline ZnO,silver micro-flakes,perovskite materials
更新于2025-09-19 17:13:59
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Device characteristics and material developments of indoor photovoltaic devices
摘要： Indoor photovoltaics (IPVs), which convert the indoor light energy into direct electricity, have attracted research attention due to their potential use as an excellent amicable solution of sustainable power source to drive low-power-needed sensors for the internet of things (IoT) applications. Our daily life adopts various indoor light sources, such as indirect sunlight, incandescent lamps, halogen lamps, ?uorescent lamps, and LED bulbs, that typically deliver lower light intensity (200–1000 lux) as compared to that of sun light (～100,000 lx). In this review, we ?rstly classi?ed the indoor lights depending on their working mechanism and resulting emission spectrum. Because the indoor light intensities are rather low that may lead to overestimate/underestimate the power conversion e?ciency (PCE) of IPV devices, then, the cautious points for correctly measuring the indoor light intensity as well as the device characteristics are summarized. Several light sources with various light intensities are reported so far, but for lack of common or standard calibration meter that induces a ambiguity in PCE determination, so we suggest/propose to use a universal LED lux meter with NIST-traceable calibration (e.g. Extech LT40-NIST) and also recommended the device results are expressed in maximum power point Pmax along with PCE values. It is generally believed that the materials play key roles on the performance of the IPV devices. Since the indoor light intensity is much weaker as compared to that of outdoor irradiation, the typical inferior photo-stability of organic materials under sunlight may not be as crucial as we considered to harvest indoor light energy, opening a great room for organic IPV material developments. In principle, all materials for outdoor PVs may also be useful for IPVs, but the fundamental material requirement for IPVs which needs su?ciently covering the absorption range between the 350–700 nm with high molar extinction coe?cient should be primarily concerned. In order to get the thorough knowledge of materials for achieving better e?cient IPVs, the reported IPVs were collected and summarized. According to these reports, the materials utilized for IPVs have been classi?ed into two major groups, inorganic and organic materials, then divided them into several sub-classes, including (1) silicon and III-V semiconductor photovoltaics, (2) dye-sensitized photovoltaics, (3) organic photovoltaics, and (4) perovskite-based photovoltaics, depend on their structural nature and device working principle. For every individual class, the structure-property-e?ciency relationship of the materials was analyzed together with the highlights on the best e?ciency material, challenge and perspective. For inorganic IPV materials, III-V semiconductor GaAs-based IPVs performed a very impressive PCE (28%). For dye sensitizers, there are more ?exible strategies to modulate the absorption pro?les of organic materials. A high e?ciency dye-sensitized solar cell (DSSC)-based IPV with a PCE up to 32% has been successfully realized with co-sensitized dyes. For organic solar cell (OSC)-based IPVs, fullerene-based acceptors are advantageous for their well-matching desired absorption range and superior electron transport features. A recent OSC-based IPV with the active layer composed of dithienobenzene-based donor and fullerene acceptor was reported to deliver a PCE of 28%. Among these emerging photovoltaic materials, it is no doubt that perovskites (e.g. CH3NH3PbI3) are superior for solar energy conversion due to the crystallinity for good charge transport, better spectral coverage and the low exciton binding energy. Until very recent, a perovskite-based IPV with a PCE of 35% was reported with good stability by the incorporation of an ionic liquid for e?ectively passivating the surface of the perovskite ?lm, indicating the bright prospect of perovskite for IPV application. Overall, the review on these reports implies the essential criteria of materials suitable for IPVs that may trigger new ideas for developing future champion materials for various devices and the realization of practical IPV applications.
关键词： Organic solar cells,Dye-sensitized solar cells,Silicon and III-V semiconductors,Perovskite materials,Power conversion efficiency,Internet of Things,Organic materials,Indoor photovoltaics
更新于2025-09-16 10:30:52
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Cs Oleate Precursor Preparation for Lead Halide Perovskite Nanocrystal Synthesis: The Influence of Excess Oleic Acid on Achieving Solubility, Conversion, and Reproducibility.
摘要： In the colloidal synthesis of inorganic perovskite materials, cesium oleate (CsOL) is the most commonly used Cs precursor. Yet despite its ubiquitous use in literature, CsOL has been observed to be insoluble at room temperature and leads to surprisingly inconsistent results in CsPbX3 nanocrystal synthesis depending on the Cs salt from which the precursor is derived. We show that under the conditions used in most reports, the amount of oleic acid (OA) added, while stoichiometrically sufficient, still leads to incomplete conversion of the Cs salts to CsOL. This results in a mixture of Cs sources being present during the reaction, causing decreased homogeneity and reproducibility. When a 1:5 Cs:OA ratio is used, complete conversion is readily obtained even under mild conditions, resulting in a precursor solution that is soluble at room temperature and yields identical synthetic results regardless of the initial Cs source. Further, 1H nuclear magnetic resonance (NMR) of solutions prepared using varying Cs:OA ratios shows that the maximum ratio of Cs:OA obtainable in solution is 1:5, with any excess Cs present in the precipitate. We believe the use of a soluble, fully converted CsOL reagent will improve reproducibility for Cs-based perovskite synthesis and directly benefit synthetic methods based on microfluidics.
关键词： reproducibility,inorganic perovskite materials,microfluidics,CsPbX3 nanocrystal synthesis,colloidal synthesis,oleic acid,solubility,cesium oleate
更新于2025-09-04 15:30:14