Inorganic Buffer Research Articles

Measures to Improve the Stability of Perovskite Solar Cells

Perovskite materials are considered to be the ideal materials in solar cell production because of their excellent natures, which have received a wide attention. Perovskite solar cell (PSC) is expected to replace the silicon-based solar cell and become the new generation of solar cell technology, because of its low cost, simple process flow and high photoelectric conversion efficiency (PCE). However, the stability of the PSC has been restricting its commercial development. In recent years, much research has been carried out to improve its stability. This review describes the construction of perovskite material, the composition of PSC and the key factors affecting the stability of PSC, including humidity stability, temperature stability and light stability, then takes inorganic buffer layer, ionic liquids and cation doping three methods as examples to summarize the mechanisms and strategies of improving the stability of PSC, and points out the great potential of multi-functional ionic liquids to improve the stability and efficiency of PSC in future.

The Investigation of the Influence of a Cu2O Buffer Layer on Hole Transport Layers in MAPbI3-Based Perovskite Solar Cells.

The passivation engineering of the hole transport layer in perovskite solar cells (PSCs) has significantly decreased carrier accumulation and open circuit voltage (Voc) loss, as well as energy band mismatching, thus achieving the goal of high-power conversion efficiency. However, most devices incorporating organic/inorganic buffer layers suffer from poor stability and low efficiency. In this article, we have proposed an inorganic buffer layer of Cu2O, which has achieved high efficiency on lower work function metals and various frequently used hole transport layers (HTLs). Once the Cu2O buffer layer was applied to modify the Cu/PTAA interface, the device exhibited a high Voc of 1.20 V, a high FF of 75.92%, and an enhanced PCE of 22.49% versus a Voc of 1.12 V, FF of 69.16%, and PCE of 18.99% from the (PTAA/Cu) n-i-p structure. Our simulation showed that the application of a Cu2O buffer layer improved the interfacial contact and energy alignment, promoting the carrier transportation and reducing the charge accumulation. Furthermore, we optimized the combinations of the thicknesses of the Cu2O, the absorber layer, and PTAA to obtain the best performance for Cu-based perovskite solar cells. Eventually, we explored the effect of the defect density between the HTL/absorber interface and the absorber/ETL interface on the device and recommended the appropriate reference defect density for experimental research. This work provides guidance for improving the experimental efficiency and reducing the cost of perovskite solar cells.

Room-temperature deposited fluorine-doped tantalum pentoxide for stable organic solar cells

Earth-abundant transition metal oxides deposited at room temperature with low-cost methods suitable for large area manufacturing can offer advances in many fields of energy related devices. Here we report the room-temperature deposition of a fluorine-doped tantalum pentoxide using a home-made, low-cost hot-wire deposition system. This novel tantalum oxyfluoride material is super hydrophobic, ultra-transparent within the visible spectrum, and possesses adequate conductivity and suitable valence band and conduction band extrema for acting as efficient hole extraction and electron blocking layer in organic solar cells with the forward architecture. By inserting this material in the form of nanoparticles deposited on top of the commonly used as hole transport layer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, higher efficiencies compared to the reference cells without the nanoparticles were demonstrated in solar cells based on blends of polymer donors with either a fullerene (where maximum achieved efficiency was improved from 6.07% to 7.90%) or a non-fullerene acceptor (reaching values of 13.48% compared to 11.32% of the reference cell). Moreover, significant improvement in device stability was achievd in unencapsulated devices continuously exposed in a humid environment for 500 h. This work demonstrates the unambiguous potential of well-designed metal oxide materials as charge transport and blocking interlayers and protective buffers in organic solar cells and beyond. Home-grown fluorine-doped tantalum pentoxide nanoparticles deposited on top of PEDOT:PSS hole transport layer results in around 19% improved power conversion efficiency and an improved stability in organic solar cells. • Room-temperature deposition of fluorine-doped tantalum pentoxide. • Improved hole extraction and electron blocking properties. • Ta 2 O 5 :F - an inorganic protective buffer layer. • A 19% improved efficiency in organic solar cells. • Improved stability of fullerene and non-fullerene acceptor.

A novel inorganic redox buffer of r-GO/Ag@AgCl/TMMCl utilized as an effective ion-to-electron transducer for a solid contact calcium ion-selective electrode

The Ag@AgCl/1-tetradecyl-3-methylimidazolium chloride (TMMCl) reported as an inorganic redox buffer for solid contact ion-selective electrodes (SC-ISEs) suffers from minimized specific area for an aggregation of Ag nanoparticles and decreased electron transfer for a presence of AgCl coating. Herein, a novel optimized inorganic redox buffer of r-GO/Ag@AgCl/TMMCl with improved capacitance and electron transfer behaving well as an effective ion-to-electron transducer for a SC-Ca2+-ISE has been highlighted. With reduced graphene oxide (r-GO) introduced as a substrate, the produced Ag nanoparticles as well as the subsequently synthesized core-shell Ag@AgCl nanomaterials display high dispersity with diameters decreased to 10–40 nm. Cyclic voltammetry with better redox reversibility and higher areas for the r-GO/Ag@AgCl/TMMCl verifies its improved redox capacitance and acceleration in electron transfer. Taking advantage of the r-GO/Ag@AgCl/TMMCl, the fabricated SC-Ca2+-ISE exhibits a near Nernst slope about 28.5 mV/dacade between potentials to Ca2+ concentrations ranging from 10−6 to 10−3M. Additionally, a diminished Rbc and Rct as well as an increased capacitance are also exemplified by the EIS and chronopotentiometric techniques, which would ensure a fast and stable potentiometric response. Moreover, the fabricated SC-Ca2+-ISE displays a good selectivity and water layer resistance. Thanks to the increased redox capacitance of the r-GO/Ag@AgCl/TMMCl, the fabricated SC-Ca2+-ISE demonstrates stable potentiometric response and good E0 reproducibility.

Improving water-resistance of inverted flexible perovskite solar cells via tailoring the top electron-selective layers

Inverted flexible perovskite solar cells (FPSCs) offer a promising route towards commercialization by using undoped inorganic hole transport layers and thermally-stable electron transport layers (ETLs), which deliver good environmental stability such as water resistance. But the power-conversion-efficiencies (PCEs) of inverted flexible perovskite cells are still far below those of FPSCs in regular configuration so far. One main challenge for achieving high-performance FPSCs lies in optimizing the ETLs and their adjacent buffering layers. Herein, we modify the fullerene derivatives (Phenyl-C61-butyric acid methyl ester, PCBM) ETLs by adding 3-aminopropyl triethoxysilane (APTS) molecules into the PCBM solutions. The addition of APTS results in smoother and denser PCBM layers via a physically steric-hindrance effect mechanism, which could benefit the electron collection between the PCBM layer and the perovskite layer. More importantly, APTS can offer nucleating sites, such as amine groups or hydroxy groups by partially hydrolyzing, to grow conformal tin oxide (SnO x ) layers by atomic layer deposition (ALD), which acts as robust buffer layers to replace traditional bathocuproine (BCP) layer. Finally, high-performance inverted FPSCs based on the optimized PCBM/SnO x electron-selective layers are fabricated, delivering a best PCE of 18.62%. The unencapsulated FPSC showed a slow decay and remained above 90% of its initial PCE after being stored for more than 600 h in a damp environment with a humidity of more than 85% R.H. The strategy is demonstrated to be applicable in the future large-scale production of stable FPSCs. • A flatter PCBM layer can reduce contact resistance and improve electron collection in inverted perovskite solar cells. • Modifying the PCBM layer with silane agents is helpful for the subsequent ALD growth of the inorganic buffer layer. • An optimized PCBM/SnO x electron selective layer endows flexible perovskite solar cells with outstanding water resistance.

Optimized Interfaces in Anti-Perovskite Electrolyte-Based Solid-State Lithium Metal Batteries for Enhanced Performance.

Solid-state lithium metal batteries have attracted broad interest as a promising energy storage technology because of the high energy density and enhanced safety that are highly desired in the markets of consumer electronics and electric vehicles. However, there are still many challenges before the practical application of the new battery. One of the major challenges is the poor interface between lithium metal electrodes and solid electrolytes, which eventually lead to the exceptionally high internal resistance of the cells and limited output. The interface issue arises largely due to the poor contact between solid and solid, and the mechanical/electrochemical instability of the interface. In this work, an in situ “welding” strategy is developed to address the interfacial issue in solid-state batteries. Microliter-level of liquid electrolyte is transformed into an organic–inorganic composite buffer layer, offering a flexible and stable interface and promoting enhanced electrochemical performance. Symmetric lithium–metal batteries with the new interface demonstrate good cycling performance for 400 h and withstand the current density of 0.4 mA cm−2. Full batteries developed with lithium–metal anode and LiFePO4 cathode also demonstrate significantly improved cycling endurance and capacity retention.

Promoting the hole extraction and interfacial performance with MOFs derived Co3O4@NC for efficient carbon-based perovskite solar cells

Carbon-based perovskite solar cells (C-PSCs) facilitate modularization and commercialization due to their excellent thermal stability and low cost. However, C-PSCs show the poor performance that charge carrier extraction by the carbon electrode alone is not as efficient as in the case of conventional hole transport materials (HTMs) based PSCs. In this work, an inorganic hole buffer layer of nitrogen-doped carbon/Co3O4 (Co3O4@NC) nanoparticles derived from MOFs is introduced to adjust energy alignment and passivate perovskite (PSK) grain boundaries (GBs). Moreover, a simple processing method on the Co3O4@NC nanoparticles manipulated by controllable ultraviolet/ozone (UVO) treatment is employed, to further improve the interfacial performance of MAPbI3/Co3O4@NC and reduce the hysteresis. Through interface engineering, it is found that Co3O4@NC inorganic hole buffer layer effectively promotes photo‐generated charge separation and extraction, and suppresses charge recombination at the MAPbI3/Carbon electrode (CE) interface, resulting in improved photovoltaic performance. Consequently, the optimal C-PSCs without encapsulation achieved a maximum PCE of 14.63%, which is 22.3% more efficient than the pristine device (11.96%), and exhibited outstanding long-term stability.

Молекулярна діагностика на основі кутової спектроскопії поверхневих плазмонів

With the purpose to reliably detect specific antibodies against the Epstein–Barr virus (EBV) and cardiovascular system molecular markers (myoglobin and fibrinogen) levels in the buffer solutions, human blood plasma and serum, it has been analyzed some techniques for protein immobilization from immune pair (antibody, antigen) onto the gold surface, as well as for increasing of sensor device («Plasmon» series instrument) sensitivity, stability and productivity, which based on surface plasmon angular spectroscopy with prism excitation.Immobilization of the EBV proteins was performed within the protective-orienting coating — three-dimensional structure of the polysaccharide dextran hydrogel deposited onto the gold film surface on glass substrate, the remaining free sites were blocked with bovine serum albumin molecules (1% BSA) to prevent non-specific interaction, and test the human blood serum from patient with EBV infection under 1:100 delusion in citrate buffer. For oriented attaching of monoclonal antibodies of mouse against the human myoglobin on the surface of gold protein A Staphylococcus aureus conjugate was used, and carry out investigation in human blood serum without delusion. The procedure of formation of am inorganic buffer layer on the surface of a chip for the site-oriented immobilization of biological receptors with the use of the step-like self-organization of the complex ferrocyanides of transition metals (five-ply film of copper aminopentacyanoferrate Cu3 [Fe(CN)5NH3]2) is developed. This gives possibility to get the concentration and calibrating curves (maximum sensitivity of 0,5 μg/ml) for the model fibrinogen in phosphate buffer, and to determine the concentration of fibrinogen in donors blood plasma under 1:300.A four-channel modification of the «Plasmon» series device with successive inquiry of photodiodes massif and with application of comparison reference channel to minimize the effect of the temperature change induced noise has been constructed for the laboratory studies execution. For the large-scale testing of the population, we propose a construction of the sensor in disk format on the basis of the prism scheme of excitation of SPR in the Kretschmann configuration with optical scanning over angles, where a planar chip with integrated gratings for the input-output of light was used as a sensor unit. Fig.: 14. Refs: 45 titles.

Rapid Vapor-Phase Deposition of High-Mobility p-Type Buffer Layers on Perovskite Photovoltaics for Efficient Semitransparent Devices

Perovskite solar cells (PSCs) with transparent electrodes can be integrated with existing solar panels in tandem configurations to increase the power conversion efficiency. A critical layer in semi-transparent PSCs is the inorganic buffer layer, which protects the PSC against damage when the transparent electrode is sputtered on top. The development of n-i-p structured semi-transparent PSCs has been hampered by the lack of suitable p-type buffer layers. In this work we develop a p-type CuOx buffer layer, which can be grown uniformly over the perovskite device without damaging the perovskite or organic charge transport layers, can be grown using industrially scalable techniques and has high hole mobility (4.3 +/- 2 cm2 V-1 s-1), high transmittance (>95%), and a suitable ionisation potential for hole extraction (5.3 +/- 0.2 eV). Semi-transparent PSCs with efficiencies up to 16.7% are achieved using the CuOx buffer layer. Our work demonstrates a new approach to integrate PSCs into tandem configurations, as well as enable the development of other devices that need high quality p-type layers.

Solution preparation of molybdenum oxide on graphene: a hole transport layer for efficient perovskite solar cells with a 1.12 V high open-circuit voltage

Recently, based on the tremendous progresses in performance of perovskite solar cells (PSCs), the inverted planar PSCs have attracted attentions for future applications. Since the traditional poly(3,4-ethylenedioxythiophene) hole transport layer could cause a loss of open-circuit voltage (Voc), some organic and inorganic alternatives have been widely investigated. However, the Voc is still below for the demand of optimized value. Here, we demonstrate that the reduced graphene oxide (RGO) doping is a facile and effective method to make molybdenum oxide (MoOx) as a promising hole transport layer (HTL) for high-performance PSCs. The conductive MoOx:RGO HTL can facilitate perovskite crystallization and reduce the potential losses of Voc in devices. Thus, a high PCE of up to 18.15% is achieved which simultaneously possesses a high Voc of 1.12 V. With this strategy, the MoOx:RGO provides a novel hole transport layer for high performance and decently stable optoelectronic devices. More importantly, it opens up the research significance of doping in inorganic buffer interlayers for the perovskite solar cells.

A solid-contact Ca2+-selective electrode based on an inorganic redox buffer of Ag@AgCl/1-tetradecyl-3-methylimidazolium chloride as ion-to-electron transducer

For construction of solid-contact ion-selective electrodes (SC-ISEs), ion-to-electron transducers based on the redox capacitance transduction mechanism are currently restricted to organic materials. Exploring inorganic nanomaterials with high redox buffer capacities as intermediate layers for SC-ISEs would offer another alternative. Herein, a solid-contact calcium ion-selective electrode (SC–Ca2+-ISE) with a new inorganic redox buffer-Ag@AgCl/1-tetradecyl-3-methylimidazolium chloride (TMMCl) as the ion-to-electron transducer is presented. In this system, the predominant component core-shell Ag@AgCl nanoparticles with diameters ranging from 30 to 100 nm can be prepared through a two-step process. An ionic liquid TMMCl is used to offer a source of free Cl−. The developed SC-Ca2+-ISE exhibits a near Nernstian slope of 28.3 mV/decade for Ca2+ in the range of 10−6 - 10−2 M. By using of the inorganic redox buffer, the SC-Ca2+-ISE has a smaller impedance and higher capacitance than the coated-wire electrode, which guarantees a stable potential response. Additionally, the proposed SC-Ca2+-ISE shows excellent resistances to interferences of light, O2 and CO2, with a reduced water layer formed between the ion-selective membrane and the underlying solid contact. The developed inorganic redox buffer of Ag@AgCl/TMMCl can be effectively used as a new ion-to-electron transducer for construction of solid contact ISEs.

Efficient and Stable Inverted Quantum Dot Light-Emitting Diodes Enabled by An Inorganic Copper-Doped Tungsten Phosphate Hole-Injection Layer.

Inorganic interfacial buffer layers have widely been employed for efficient and long lifetime optoelectronic devices due to their high carrier mobility and excellent chemical/thermal stability. In this paper, we developed a solution-processed inorganic tungsten phosphate (TPA) as hole injection layer (HIL) in inverted quantum dot light-emitting diodes (QLEDs) achieving a high external quantum efficiency (EQE) of up to ∼20%. Further, the copper ions are doped into tungsten phosphate (Cu:TPA) which leads to an enhancement in hole injection due to increased hole mobility and conductivity of TPA as well as decreased hole injection barrier, enabling better charge balance in QLEDs and lower turn-on voltage from 5 to 2.5 V. Compared with the devices using conventional organic poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) HIL, the half-lifetime of Cu:TPA-based devices is over 3000 h at an initial brightness of 100 cd m-2, almost 5-fold operating lifetime enhancement.

Characterization studies of NiO:K anode buffer layer in Alq3 and TADF-based organic light-emitting diodes by secondary ion mass spectrometry and admittance spectroscopy

In this paper, we used thermal evaporation method to deposit metal oxide films as inorganic buffer layer in Organic light-emitting diodes (OLEDs), and investigated how the K2CO3-doped NiO (KNO) buffer layers affect OLEDs’ performances. The mechanisms of enhanced hole injection into the hole transport layer NPB (α-naphthylphenylbiphenyl diamine) via NiO:K2CO3 anode buffer layers in Alq3-based and TADF-based OLEDs were studied by means of J-V-L characteristics, secondary ion mass spectroscopy (SIMS), and admittance spectroscopy measurements. For Alq3-based OLEDs, devices’ opto-electrical performances showed increased of luminance from 8780 cd/m2 to 22940 cd/m2, the decreased of turn-on voltage from 3.4 V to 3.1 V at 1 mA/cm2, and increased of current efficiency from 4.3 cd/A to 3.48 cd/A when 1-nm-thick K2CO3-doped NiO film with doping concentration of 1 mol% was inserted into OLEDs. TADF-based OLEDs’ current efficiency increased from 21.7 cd/A to 29.7 cd/A with similar anode buffer layer parameters. SIMS depth profiles on OLEDs suggested higher indium (In) diffusion from ITO anode onto TADF-based OLEDs upon device operation leading to higher roll-off phenomenon. Deposition of NiO:K2CO3 as anode buffer layer onto OLEDs device reduced the diffusion of In in organic layers during device operation. Investigation of the capacitance as function of voltage and frequency yield information about carrier injection characteristics for both Alq3 and TADF-based OLEDs. Due to better carrier recombination capability, TADF-based OLEDs’ slope in V > Vbi area has fewer shifts and more stable response, leading to higher amplitude in current efficiency enhancement in comparison with fluorescents (Alq3) material.

Improved hole-injection and external quantum efficiency of organic light-emitting diodes using an ultra-thin K-doped NiO buffer layer

In this paper, we used the thermal evaporation method to deposit K-doped NiO (KNO) films as the inorganic buffer layer in thermally activated delayed fluorescence (TADF)-based organic light emitting diode (OLED) devices, and investigated how it improved device performance. The device configuration was ITO/NiO:K2CO3 (X mol%, 1 nm)/NPB (40 nm)/CBP:4CzIPN (5 wt%, 20 nm)/TPBi (50 nm)/LiF (1 nm)/Al (150 nm). We used various concentrations of alkali metal-doped metal oxide on the ITO, which was then subjected to UV-O3 surface treatment. We studied the effects and mechanisms of the improved hole-injection properties of the OLEDs with different measurement methods. X-ray Photoelectron Spectroscopy (XPS) was used to measure the molecular binding energy and confirm formation of the K-doped NiO films. In comparison with the ITO electrode's work function, the KNO film increased the work function from 4.8 to 5.3 eV. Contact angle measurement showed that the deposition of the buffer layer increased both polarity and surface energy. The K-doped NiO film was found to have a smoother surface than that of the ITO electrode, as determined by Atomic Force Microscopy. Reduction in the sheet resistance of the OLEDs was revealed by Admittance Spectroscopy measurement. The opto-electrical performances of the devices showed an increase in luminance from 18420 cd/m2 to 36740 cd/m2, a decrease in turn-on voltage from 4.3 V to 3.9 V at 100 cd/m2, and an increase in external quantum efficiency (EQE) from 7.1% to 9.76% when a 1-nm-thick KNO film with a doping concentration of 1 mol% was inserted into the OLEDs.

Highly efficient photovoltaic energy storage hybrid system based on ultrathin carbon electrodes designed for a portable and flexible power source

Integrated perovskite solar capacitor (IPSC) systems are the new paradigm for power generation and storage. Herein, a novel configuration and combination of materials for an IPSC, theoretically affording a maximized areal capacitance of 2.35 mF cm−2 and exceeding a 25% overall photo-chemical-electricity energy conversion efficiency is reported. A ∼1 μm solid-state photocapacitor is suggested based on a CH3NH3PbI3 photoactive layer, inorganic buffer junctions, an ultrathin nanocarbon border and top electrodes. For the first time, bulk and interfacial imperfections in the perovskite layer are reckoned in simulation, realizing the recombination rate to 14-order of magnitude higher than that in the perfect perovskite structure. The simulation considers the band gap energy, the valance and conduction bands, carrier mobility and carrier density of every individual layer of the designed IPSC. Overall, the results for the areal capacitance, output voltage and photocharging efficiency under various illumination conditions, frequencies and dielectric materials show that the performance of the perovskite power pack is mildly susceptible to external and internal triggers. This ultrathin and sturdy architecture, shows promise for use in self-powered portable and wearable personal devices.

An explanation of the reversal of erythrocyte echinocytosis by incubation and storage by serum albumin

It is proposed that the specific reversal by serum albumin of the erythrocyte echinocytosis in an inorganic phosphate buffer saline or in a saline, either after 24 h in blood or after a storage of 6-7 weeks in SGAM or PAGGSM media, is due to a cell dehydration by a decrease of the total NaCl and KCl concentrations favoring the stomatocytogenic slow outward transport of inorganic phosphate with a hydrogen ion by band 3 anion exchanger, which was previously proposed to control the erythrocyte shape. This proposal would indicate that the opposition of the erythrocyte echinocytosis by serum albumin is not limited to binding to echinocytogenic amphiphiles, supported by the ability of the band 3-based mechanism of control of the erythrocyte shape to explain a variety of observations on the erythrocyte shape. It would also imply that this mechanism is a determinant of the erythrocyte rheological properties since influenced by cell shape and volume. It is shown that the above process of stomatocytosis can explain stomatocytoses by different agents as well as a knizocytosis induced in vitro and occurring in acquired and inherited disorders and other situations. Lastly, it can also explain the opposition of hemolysis by mannitol in SGAM and PAGGSM media.

Copper iodide-PEDOT:PSS double hole transport layers for improved efficiency and stability in perovskite solar cells

The hole transport layer (HTL) plays an important role in perovskite solar cells (PSCs). We demonstrate the cupper iodide (CuI)/poly (3,4-ethylenedioxythiophene) poly (styrenesulphonate) (PEDOT:PSS) double layers as the anode buffer layer for efficient hole transport in PSCs. An obvious enhancement of open-circuit voltage and power conversion efficiency (PCE) is observed, and a final PCE of 14.3% is achieved. While the single PEDOT:PSS based device’s PCE is 12.9%. The inorganic CuI buffer layer significantly enhanced the hole extraction from the perovskite film, as revealed from the photoluminescence spectra. The average exciton lifetime is reduced to 2.7 ns. Moreover, the devices with double HTLs structure exhibit better long time stability. The PCE remains 88% of the initial value after 720 h’ storage.

High dielectric constant and energy density induced by the tunable TiO2 interfacial buffer layer in PVDF nanocomposite contained with core–shell structured TiO2@BaTiO3 nanoparticles

To realize application in high-capacity capacitors and portable electric devices, large energy density is eagerly desired for polymer-based nanocomposite. The core–shell structured nanofillers with inorganic buffer layer are recently supposed to be promising in improving the dielectric property of polymer nanocomposite. In this work, core–shell structured TO@BT nanoparticles with crystalline TiO2 buffer layer coated on BaTiO3 nanoparticle were fabricated via solution method and heat treatment. The thickness of the TO buffer layer can be tailored by modulating the additive amount of the titanate coupling agent in preparation process, and the apparent dielectric properties of nanocomposite are much related to the thickness of the TO layer. The relatively thin TO layer prefer to generate high polarization to increase dielectric constant while the relatively thick TO layer would rather to homogenize field to maintain breakdown strength. Simulation of electric field distribution in the interfacial region reveals the improving effect of the TO buffer layer on the dielectric properties of nanocomposite which accords with the experimental results well. The optimized nanoparticle TO@BT-2 with a mean thickness of 3–5 nm buffer layer of TO is effective in increasing both the ε and Eb in the PVDF composite film. The maximal discharged energy density of 8.78 J/cm3 with high energy efficiency above 0.6 is obtained in TO@BT-2/PVDF nanocomposite with 2.5 vol% loading close to the breakdown strength of 380 kV/mm. The present study demonstrates the approach to optimize the structure of core–shell nanoparticles by modulating buffer layer and provides a new way to further enlarge energy density in polymer nanocomposite.

Hydrophilic interaction liquid chromatography in the speciation analysis of selenium

The hydrophilic interaction liquid chromatography (HILIC) coupled to mass spectrometry was employed to study retention behavior of selected selenium compounds using two different HILIC stationary phases: silica and zwitterionic. Two organic solvents – acetonitrile and methanol – were compared as a component of mobile phase. Separation parameters such as a content of organic modifier, the eluent pH and inorganic buffer concentration were investigated. Based on all observations, methanol seems to be beneficial for the separation of studied compounds. The optimal HILIC separation method involved silica column and eluent composed of 85% MeOH and CH3COONH4 (8 mM, pH 7) was compared to RP method in terms of time of the single run, the separation efficiency and limit of detection.

Improving electron transport in the hybrid perovskite solar cells using CaMnO3-based buffer layer

In the present article, the detailed analyses of interface properties and device performance of inorganic perovskite CaMnO3-based buffer layer hybrid perovskite solar cell have been undertaken. Analyses are based on ab initio simulations and macroscopic modelling. A thorough study of electronic and optical properties and interface charge dynamics revealed that CaMnO3 presents a better candidate for the electron transport material in thin film hole transporting material free hybrid perovskite solar cells with the planar architecture than the most common anatase TiO2. This result is founded on the more appropriate band gap and better band alignment with the hybrid perovskite, leading to the faster charge carrier mobility, improved charge transfer and reduced exciton recombination. The results from theoretical simulations are justified by the solar cell model, which explored the basic cell characteristics and parameters: open circuit voltage, short circuit current, fill factor and efficiency, as the functions of cell performance factors, like defect density, diffusion length, absorber layer thickness and band offset. Our model suggests an unoptimized device with a photo-conversion efficiency of almost 10% for the low defect concentrations under 1015. With efficiency in the upper range for HTM free perovskite solar cells, we propose that the CaMnO3-based solar cell poses as an improvement upon the up to now most frequently used ones and provides important step toward their commercialisation.