Sequential Deposition Method Research Articles

Constructing Graded Perovskite Homojunctions by Adding Large Radius Phenylmethylamine Ions for Sequential Spin-Coating Deposition Method To Improve the Efficiency of Perovskite Solar Cells

Cs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method due to its outstanding photovoltaic and stability performances. This work constructs a quadruple-...

New insights into interaction of proteins in extracellular polymeric substances of activated sludge with ciprofloxacin using quartz crystal microbalance with dissipation

Proteins in extracellular polymeric substances play a vital role in adsorbing organic contaminants in biological wastewater treatment processes, but there is still lack of a fast and effective approach to monitor their interaction. Quartz crystal microbalance with dissipation (QCM-D) was used to investigate the binding and viscoelastic properties of ciprofloxacin (CIP) on extracellular proteins from activated sludge by a two-step sequential deposition method. A saturated viscoelastic monolayer of proteins was formed on the crystal by injecting 500 mg L−1 extracellular proteins. Binding of CIP with the extracellular proteins film followed the pseudo-first-order kinetic equation and Langmuir model, with the maximum binding capacity of 172.4 mg g−1. The binding mass, energy dissipation, and reaction rate constant increased with increasing CIP concentration. A strong binding was obtained at pH 5, suggesting electrostatic interactions as the dominating binding mechanism. Cations inhibited CIP binding with extracellular proteins, probably due to cations competition. Two binding periods were distinguished according to the viscoelastic properties of CIP layer: viscous binding in the initial period and elastic towards binding saturation. Results highlighted QCM-D as an effective and real-time technique to evaluate the role of extracellular proteins in contaminants removal.

Novel mixed solution of ethanol/MACl for improving the crystallinity of air-processed triple cation perovskite solar cells

In recent years, perovskite solar cells (PSCs) have attracted considerable attention due to their low-cost and simple fabrication. Among the perovskite materials, Cs/FA/MA triple cation perovskites, because of its outstanding photovoltaic (PV) properties and stability, have been developed. In this research, triple cation PSCs were fabricated by using a sequential deposition method (SDM) without anti-solvent in ambient air. A novel low-cost mixed solution of ethanol/MACl (Et-M) was introduced into the FAI/MABr precursor to boost crystal grain size and surface quality of triple cation perovskite films. Photovoltaic devices based on Et-M additive demonstrate a higher averaging efficiency of 13.18% than 9.49% of the without additive devices. Results revealed that our new suggested Et-M additive increase crystal grain size more than the conventional MACl additive method in ambient air. Additionally, the defects passivation by Et-M additive increased the ambient and thermal stability of devices. It led to Et-M based devices retain 84% of their initial efficiency (76% for devices with MACl additive) within the 1500 h aging time in dry airbox (30% RH). Obtained results show a low-cost and simple method to improve PV performance and stability of fully ambient air processed triple cation PSCs.

Design of a thermally resistant core@shell/halloysite catalyst with optimized structure and surface properties for a Pd-only three-way catalyst

In this study, two types of core@shell nanoparticles, CeO2@Pd and inverse Pd@CeO2 nanoparticles, were synthesized by sequential deposition and electrostatic attraction-induced deposition method, respectively. Then, the core@shell nanoparticles supported on halloysite were thermally treated at different temperatures, and the nascent core@shell/H-x catalysts were characterized and evaluated for their three-way catalytic performance. During the thermal treatment (650 °C, 800 °C, and 1100 °C), the CeO2@Pd/H-x catalysts showed strong temperature sensitivity, resulting in aggregation of the active metal particles, degradation of the textural properties, and weak interactions between the active sites and support, accompanied by the deactivation of the three-way reaction. Remarkably, Pd@CeO2/H-800 exhibits excellent catalytic performance because it has an appropriate Pd-CeO2 interaction and high thermal stability, which effectively suppresses the encapsulation and aggregation of Pd@CeO2 nanoparticles and imparts a high content of Ce3+ species and oxygen vacancies and equivalent of Pd2+/Pd° ratio.

Optimized active layer morphology toward efficient and polymer batch insensitive organic solar cells

Morphology control in laboratory and industry setting remains as a major challenge for organic solar cells (OSCs) due to the difference in film-drying kinetics between spin coating and the printing process. A two-step sequential deposition method is developed to control the active layer morphology. A conjugated polymer that self-assembles into a well-defined fibril structure is used as the first layer, and then a non-fullerene acceptor is introduced into the fibril mesh as the second layer to form an optimal morphology. A benefit of the combined fibril network morphology and non-fullerene acceptor properties was that a high efficiency of 16.5% (certified as 16.1%) was achieved. The preformed fibril network layer and the sequentially deposited non-fullerene acceptor form a robust morphology that is insensitive to the polymer batches, solving a notorious issue in OSCs. Such progress demonstrates that the utilization of polymer fibril networks in a sequential deposition process is a promising approach towards the fabrication of high-efficiency OSCs.

Nanocrystalline Heterogeneous Multiferroics Based on Yttrium Ferrite (Core) with Calcium Zirconate (Titanate) Shell

Nanocrystalline YFeO3–CaZr(Ti)O3 powders were synthesized by the sequential deposition method. The structure of the YFeO3–CaZr(Ti)O3 nanocrystals fits into the core–shell spherical particle model. The nanocrystalline YFeO3–CaZr(Ti)O3 powders synthesized contain yttrium orthoferrite and calcium zirconate (titanate) single phases. Materials based on YFeO3–CaZr(Ti)O3 are magnetically soft.

Alternative sequential deposition for optimization-free multi-component organic bulk heterojunctions

Multi-component (ternary, quaternary, and beyond) bulk heterojunction (BHJ) active layers are considered one of the most effective ways of increasing the performance of organic photovoltaics (OPVs). Herein, an alternative sequential deposition method for the development of efficient multi-component OPVs without the need for the complex optimization steps typical for blend parameters is discussed. Simple sequential spin-coating of two binary donor:acceptor blends was applied to produce modified quaternary BHJ layers, making full use of the optoelectronic advantages offered by the two binary blends and their optimized morphological features. A combination of theoretical and experimental analyses revealed the occurrence of molecular reorganization during sequential deposition which facilitated self-optimized molecular stratification and cascade energy level alignment. By using expanded universality test to account for the diverse BHJ systems, this sequential deposition methodology creates new opportunities as an alternative fabrication platform to secure high-performance multi-component BHJ OPVs for versatile (i.e., indoor and outdoor) irradiation environments while overcoming many of the drawbacks of conventional manufacturing procedures. • Alternative manufacturing process of organic photovoltaics (OPVs) is demonstrated. • Sequential spin-coating of two binary blends produces modified multi-component bulk heterojunction layers. • Performance is optimized for both indoor and outdoor light conditions without the need for fine-tuned blend optimization. • Sequential deposition is a universal platform to achieve optimization-free, high-performance multi-component OPVs.

SiO2 nanoparticle-regulated crystallization of lead halide perovskite and improved efficiency of carbon-electrode-based low-temperature planar perovskite solar cells**Project supported by the Fundamental Research Funds for the Central South University, China (Grant No. 2019zzts426), the National Natural Science Foundationof China (Grant Nos. 61172047, 61774170, and 51673218), the Scientific and Technological Project of Hunan Provincial Development and Reform Commission, China, the National Science

SiO2 nanoparticles were used to regulate the crystallizing process of lead halide perovskite films prepared by the sequential deposition method, which was used in the low-temperature-processed, carbon-electrode-basing, hole-conductor-free planar perovskite solar cells. It was observed that, after adding small amount of SiO2 precursor (1 vol%) into the lead iodide solution, performance parameters of open-circuit voltage, short-circuit current and fill factor were all upgraded, which helped to increase the power conversion efficiency (reverse scan) from 11.44(± 1.83)% (optimized at 12.42%) to 14.01(±2.14)% (optimized at 15.28%, AM 1.5G, 100 mW/cm2). Transient photocurrent decay curve measurements showed that, after the incorporation of SiO2 nanoparticles, charge extraction was accelerated, while transient photovoltage decay and dark current curve tests both showed that recombination was retarded. The improvement is due to the improved crystallinity of the perovskite film. X-ray diffraction and scanning electron microscopy studies observed that, with incorporation of amorphous SiO2 nanoparticles, smaller crystallites were obtained in lead iodide films, while larger crystallites were achieved in the final perovskite film. This study implies that amorphous SiO2 nanoparticles could regulate the coarsening process of the perovskite film, which provides an effective method in obtaining high quality perovskite film.

Sequential RTV/(TiO2/SiO2) nanocomposite deposition for suppressing the leakage current in silicone rubber insulators

The sequential deposition method is introduced for suppressing the leakage current in silicone rubber insulators. Room temperature vulcanizing silicone and TiO2/silica nanocomposites are sequentially deposited on silicone insulators surface. TEM results showed that TiO2 nanoparticles size is about 20–30 nm, and the structural study revealed their anatase crystalline structure. Silica nanoparticles are deposited on the surface of insulators by spray deposition. The contact angle was enhanced from 104° to 149° after nanoparticles deposition, which confirms the hydrophobicity improvement. Results show that leakage current for nanocomposite samples in a contaminated environment reduced to about 0.02 mA, which was 1 mA in insulators without any coating, indicating a remarkable improvement after coating. The stability of bare and coated insulators was examined under kaolin, salt, NH4Cl-contaminated environment, and also UV radiation for more than 500 h. Results show that the sequential deposition could be utilized as a cost-effective and scalable method for enhancing the hydrophobicity and stability of insulators.

Facile Deposition of Mesoporous PbI2 through DMF:DMSO Solvent Engineering for Sequentially Deposited Metal Halide Perovskites

Sequential deposition is one of the most promising approaches toward achieving scalable fabrication of metal halide perovskite thin films. However, this fabrication approach conventionally lends itself to the incomplete conversion of the lead halide, which impacts the stability, performance, and reproducibility of functional devices featuring such thin films. In this work, we have overcome this limitation by using a simple solvent and process engineering approach. We show that through the use of an optimized dimethylformamide and dimethyl sulfoxide solvent mixture in the precursor solution, and through the judicious control of this solution, the substrate, and final annealing temperatures, highly uniform and mesoporous PbI2 thin films can be deposited. The porous structure of these films is found to accelerate the interdiffusion of CH3NH3I (MAI) during the second-step process when carried out at room temperature, enabling their complete conversion into CH3NH3PbI3 perovskite. Detailed investigations using scanning electron microscopy, X-ray diffraction, grazing-incidence wide-angle X-ray scattering, thermogravimetric analysis, UV–vis absorption, photoluminescence, and time-of-flight secondary ion mass spectrometry have been used to provide mechanistic insights into the porous PbI2 film formation and the interdiffusion process. Solar cells based on planar fluorine-doped tin oxide (FTO)/TiO2/CH3NH3PbI3/spiro-OMeTAD/Au device architectures yield optimized device efficiencies of 19%, which is among the highest for this device structure and perovskite absorber material. The applicability of this enhanced sequential deposition method to other perovskite systems has been further validated through the fabrication of efficient FAxMA1–xPbIxBr3–x and CsPbIxBr3–x solar cells.

Precursor engineering for performance enhancement of hole-transport-layer-free carbon-based MAPbBr3 perovskite solar cells

An optimized two-step sequential deposition method to fabricate hole-transport-layer-free carbon-based methyl ammonium lead bromide (MAPbBr3) perovskite solar cells is reported. Small amounts of MABr are introduced into the PbBr2 precursor solution during the first step to prepare MAPbBr3 perovskite films (labeled as MAPB-xMABr), which promotes the conversion of PbBr2 into perovskite phase and results in denser perovskite films with increased crystallinity, lower trap density, and longer carrier lifetime. After optimization, a maximum power conversion efficiency (PCE) of 7.64% (VOC = 1.36 V) is obtained for MAPB-0.2MABr based solar cells. Significantly, the non-encapsulated devices exhibit excellent long-term stability in ambient air (25–30 °C and 20–30% relative humidity), showing no degradation after a year’s exposure. While, it also shows superior thermal stability with PCE retaining 95% of the initial efficiency after 120 h under thermal stress of 80 °C and 40–70% relative humidity.

A cation-regulation strategy for achieving high-performance perovskite solar cells via a fully-evaporation process

Mixed-cation halide perovskite solar cells (PSCs) have received extensive attention due to their excellent optoelectronic properties and long-term stability. How to further promote its facile and large-scale film-formation procedure is of great significance for commercialization. In this work, a CsMA-based perovskite film was prepared via a two-step evaporation process. By regulating the cation ratio systematically, uniform and large-scale perovskite films can be obtained with excellent stability and high crystallization. Based on the perovskite active layer, typical PSCs were developed with a fully-evaporation technology, and the power conversion efficiency (PCE) of the champion device is 17.15% (J SC = 22.59 mA cm −2 , V OC = 1.03 V, FF = 73.71%). In addition, the PSC module was also explored (active area ≈10 cm 2 ), achieving a PCE of 10.24%. It prospects that our efforts could draw inspiration for pushing ahead the industrialization of the perovskite photovoltaic. • A simplified but powerful sequential vapor deposition method for perovskite films was proposed and developed. • Doping with the optimal concentration of Cs + can improve the PCE of PSC by more than 20%. • The PSC device maintains 85% PCE after stored in ambient condition (40% RH) for half a month. • The PSC module with an effective area of 10.8 cm 2 achieved a PCE of 10.24%.

A Polymerization-Assisted Grain Growth Strategy for Efficient and Stable Perovskite Solar Cells.

Intrinsically, detrimental defects accumulating at the surface and grain boundaries limit both the performance and stability of perovskite solar cells. Small molecules and bulkier polymers with functional groups are utilized to passivate these ionic defects but usually suffer from volatility and precipitation issues, respectively. Here, starting from the addition of small monomers in the PbI2 precursor, a polymerization-assisted grain growth strategy is introduced in the sequential deposition method. With a polymerization process triggered during the PbI2 film annealing, the bulkier polymers formed will be adhered to the grain boundaries, retaining the previously established interactions with PbI2 . After perovskite formation, the polymers anchored on the boundaries can effectively passivate undercoordinated lead ions and reduce the defect density. As a result, a champion power conversion efficiency (PCE) of 23.0% is obtained, together with a prolonged lifetime where 85.7% and 91.8% of the initial PCE remain after 504 h continuous illumination and 2208 h shelf storage, respectively.

Outstanding Photocurrent Density and Incident Photon‐to‐Current Conversion Efficiency of Liquid‐State NiO Perovskite‐Sensitized Solar Cells

The efficiency and photocurrent density reported for p‐type‐sensitized solar cells up to now are still lagging behind that of the n‐type counterparts, limiting the successful development of p–n tandem cells. To circumvent this issue, NiO thin film is fabricated by the aerosol‐assisted chemical vapor deposition (AACVD) technique and used in p‐type solar cells. A systematic study is conducted to comprehend the correlation between NiO thickness and the power conversion efficiency (PCE) of liquid‐state NiO‐based sensitized solar cells. By carefully designing the cell components, this type of device demonstrates the highest photocurrent density (Jsc) exceeding 18 mA cm−2 when using iodine/triiodide as the redox shuttle matching the one produced by the TiO2 counterpart. This is accomplished by 1) using the AACVD technique for the one‐step deposition of compact and mesoporous NiO electrodes, 2) optimizing the thickness of the NiO layer through controlling the deposition time, and 3) adopting methylammonium lead iodide (CH3NH3PbI3) as a light harvester prepared via a sequential deposition method.

Advanced Interface Engineering of CH3NH3PbI3 Perovskite Solar Cells: The Unique Role of Layered Double Hydroxide Precursor

Top-performing metal halide perovskite solar cells (PSCs) with a solar-to-electric power conversion efficiency (PCE) beyond 22% often are fabricated using sequential deposition method under a controlled atmosphere in a glovebox. Meanwhile, a maximum efficiency of 13.59% was reported for CH3NH3PbI3-based PSC using a vapor-assisted solution processing method (VASP) at fully ambient air condition (in terms of both atmosphere and pressure). Herein, we introduce island-like ZnAl-layered double hydroxide (ZnAl-LDH) precursor as middle layer arrays assembling onto the TiO2 nanoparticles (NPs) of mesoporous TiO2 (mp-TiO2) texture to obtain a surged PCE up to 18.54% with a significant performance improvement of 36.4% for fully ambient VASP processed PSCs. Moreover, this enables us to fabricate hole transporting material-free PSC with a maximum efficiency of 14.45% by using ZnAl-LDH permeated mp-TiO2 as the underneath scaffold. The synergistic effect between ZnO and ZnAl2O4 semiconductors—resulting from LDH calcination—and TiO2 NPs leads to more effective electron extraction, reduces electron back transfer as a recombination barrier, and acts as an interfacial barrier between the UV-photocatalytically active TiO2 NPs and perovskite film as well.

Alkali-cation-enhanced benzylammonium passivation for efficient and stable perovskite solar cells fabricated through sequential deposition

Compositional perovskites were developed by a sequential deposition method for highly efficient and stable solar cells. The inclusion of alkali cation and benzylammonium showed synergistic passivation-effect and demonstrated 22.5% efficiency with over 1500 h stability.

Effects of alkali and transition metal-doped TiO2 hole blocking layers on the perovskite solar cells obtained by a two-step sequential deposition method in air and under vacuum.

Planar perovskite solar cells (PPSCs) have received great attention in recent years due to their intriguing properties, which make them a good choice for photovoltaic applications. In this work, the effect of alkali and transition metal-doped TiO2 (cesium-doped TiO2 (Cs-TiO2) and yttrium-doped TiO2 (Y-TiO2)) compact layers on the optical, structural and the photovoltaic performance of the PPSCs have been investigated. The perovskite layer syntheses were carried out by depositing a lead iodide (PbI2) layer via spin-coating; converting PbI2 into methyl ammonium iodide (CH3NH3PbI3) by chemical vapor deposition (CVD) and spin-coating at 60 min and 60 s conversion times respectively. The as-deposited PPSCs were studied layer-by-layer using an X-ray diffractometer, scanning electron microscope, and UV-vis diffuse reflectance, transmittance and absorbance. The power conversion efficiency for stable processed perovskite solar cells were 3.61% and 12.89% for air and vacuum processed, respectively.

δ‐CsPbI3 Intermediate Phase Growth Assisted Sequential Deposition Boosts Stable and High‐Efficiency Triple Cation Perovskite Solar Cells

AbstractCs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method, attributable to its outstanding photovoltaic and stability performances. However, a facile and effective strategy is still lacking for fabricating high‐quality large‐grain triple cation perovskite films via sequential deposition method a, which is one of the key technologies for high efficiency perovskite solar cells. To address this issue, a δ‐CsPbI3 intermediate phase growth (CsPbI3‐IPG) assisted sequential deposition method is demonstrated for the first time. The approach not only achieves incorporation of controllable cesium into (FAPbI3)1–x(MAPbBr3)x perovskite, but also enlarges the perovskite grains, manipulates the crystallization, modulates the bandgap, and improves the stability of final perovskite films. The photovoltaic performances of the devices based on these Cs/FA/MA perovskite films with various amounts of the δ‐CsPbI3 intermediate phase are investigated systematically. Benefiting from moderate cesium incorporation and intermediate phase‐assisted grain growth, the optimized Cs/FA/MA perovskite solar cells exhibit a significantly improved power conversion efficiency and operational stability of unencapsulated devices. This facile strategy provides new insights into the compositional engineering of triple or quadruple cation perovskite materials with enlarged grains and superior stability via a sequential deposition method.

Tetrahydrofuran as an Oxygen Donor Additive to Enhance Stability and Reproducibility of Perovskite Solar Cells Fabricated in High Relative Humidity (50%) Atmosphere

In sequential deposition method of lead‐halide perovskite material, the PbI2 layer morphology and remnant PbI2 play an important role in enhancing the power conversion efficiency (PCE) of the perovskite solar cell. However, humidity levels affect the PbI2 and perovskite film morphology, resulting in defect sites and recombination centers on the surface and within the bulk of the material, thus impeding the overall device performance and stability. To address this, incorporation of tetrahydrofuran (THF) additive in PbI2–dimethylformamide (DMF) precursor solution is reported, to improve the quality of PbI2 thin films and to prevent the water interaction directly with PbI2 under high humidity environments. The O‐donor THF interacts with PbI2, resulting in a homogeneous, dense, and pinhole‐free layer as compared with the PbI2 layer without additive. The perovskite layer so obtained from the pinhole‐free PbI2 layer is compact, resulting in a significant reduction of defects/traps. The device is fabricated with modified perovskite in ≈50% humidity atmosphere, resulting in 15% efficiency with high reproducibility. Moreover, the THF‐modified non‐encapsulated perovskite device retains 80% PCE after exposure to 50% relative humidity for 20 days. A strategy to fabricate perovskite solar cells, with reproducible efficiency in high humidity atmosphere viable for large‐scale production, is demonstrated.

Sulfur-Vacancy Passivation in Solution-Processed Sb2S3 Thin Films: Influence on Photovoltaic Interfaces

We have presented a modified two-step sequential deposition method in forming Sb2S3 thin films. In contrast to conventional chemical bath deposition (CBD) route, this sequential deposition approach...