Electron Transport Processes Research Articles

Constructing an Al3+/Zn2+-Based Solid Electrolyte Interphase to Enable Extraordinarily Stable Al3+-Based Electrochromic Devices.

The interface between the electrochromic (EC) electrode and ionic conductor is crucial for high-performance and extraordinarily stable EC devices (ECDs). Herein, the effect of the ALD-AZO interfacial layer on the performance of the WO3 thin film was examined, revealing that an introduction of the ALD-AZO interfacial layer to the Al3+-based complementary ECDs can lead to improved EC performance and stability, such as an extraordinary cyclability of more than 20,000 cycles, an outstanding coloration efficiency of 109.69 cm2 C-1, and a maximum transmittance modulation of 63.44%@633 nm. The probable explanation is that the introduced ALD-AZO interfacial layer can effectively regulate the band gap of WO3, promote the electron transport process, and induce the formation of a robust solid electrolyte interphase to protect the electrode during cycling. These findings offer valuable insights for enhancing the EC performance of the EC thin films and new space for the construction of advanced multivalent Al3+-based ECDs.

Insights into the efficient water treatment over N-doped carbon nanosheets with layered minerals as template: The role of interfacial electron tunneling and transfer

Peroxymonosulfate (PMS) oxidation reactions have been extensively studied recently. Due to the high material cost and low catalytic capability, PMS oxidation technology cannot be effectively applied in an industrial water treatment process. In this work, we developed a modification strategy based on enhancing the neglected electron tunneling effect to optimize the intrinsic electron transport process of the catalyst. The 2D nitrogen-doped carbon-based nanosheets with small interlayer spacing were prepared by self-polymerization of dopamine hydrochloride inserted into the natural layered bentonite template. Systematic characterizations confirmed that the smaller layer spacing in the 2D nitride-doped carbon-based nanosheets reduces the depletion layer width. The weak electronic shielding effect derived by the small layer spacing on the material subsurface enhanced the bulk electron tunneling effect. More bulk electrons could be migrated to the catalyst surface to activate PMS molecules. The PMS activation system showed ultrafast oxidation capability to degrade organic pollutants and strong ability to resist interference from environmental matrixes due to the optimized electron transfer process. Furthermore, the developed membrane reactor exhibited strong catalytic stability during the continuous degradation of P-Chlorophenol (CP).

Local built-in electric field of oxygen vacancy generated in fluorine-doped Nb2O5 structure modified by sulfur/fluorine co-doped carbon improves lithium storage performance

Monoclinic Nb2O5 (H–Nb2O5) as an prospect anode material for lithium ion batteries due to its high theoretical specific capacity of 250 mAh g-1 and a safe working voltage in the range of 1–3 V, but the inherent low electron conductance greatly limits its high-rate performance. In this paper, we synthesized F-doped Nb2O5 with S/F co-doped carbon composites (F–Nb2O5@SFC) by simple high-temperature annealing method, XPS and EPR analysis results show that the composites has abundant of oxygen vacancies. Under the dual effects of F− doping and oxygen vacancy, the free electron concentration of Nb2O5 structure is greatly increased, and the conductive network provided by SFC accelerates the electron transport process, thus, the obtained F–Nb2O5@SFC material achieves excellent conductivity. In addition, the charge density difference results indicate that the unbalanced charge distribution around oxygen vacancies provides additional Li+ active sites, and the constructed electric field accelerates the transmission of Li+. The fast Li+/electron transfer kinetics of the F–Nb2O5@SFC electrode has achieved excellent storage performance, with a reversible specific capacity of 165 mAh g-1 at 1A g-1 after 600 cycles and a high-rate capacity of 130 mAh g-1 at 10A g-1.

Boosting the Performance of Diketopyrrolopyrrole-Triphenylamine-Based Organic Solar Cells via π-Linker Engineering.

The design and development of novel and efficient donor-π-acceptor (D-π-A) type conjugated systems has attracted substantial interest in the field of organic electronics owing to their intriguing properties. In this paper, we have designed seven new and efficient D-π-A type conjugated systems (M1-M7) by a variety of π-linkers with triphenylamine (TPA) as the electron donor and diphenyldiketopyrrolopyrrole (DPP) as the electron acceptor using density functional theory (DFT) formalism for organic solar cells (OSCs). The π-linker has been substituted between the donor and acceptor for efficient electron transfer. Here, our primary focus is on narrowing the highest occupied molecular orbital-lowest unoccupied molecular orbital gaps, electronic transition, charge transfer rate, reorganization energies, and the theoretical power conversion efficiencies (PCEs). Our study reveals that the designed compounds exhibit excellent charge transfer rates. The absorption properties of the compounds have been examined using the time-dependent density functional theory (TD-DFT) method. The TD-DFT study shows that compound M2 possesses the highest absorption maxima with a maximum bathochromic shift. For a better understanding of the electron transport process of our designed compounds, we have designed donor/acceptor (D/A) blends, and each of the developed blends (FREA/M1-M7) can encourage charge carrier separation. According to the photovoltaic performance of the D/A blends, compound FREA-M2, which has a theoretical PCE of 16.53%, is the most appealing choice for use in OSCs. We expect that by thoroughly examining the relationship between structure, characteristics, and performance, this work will serve as a roadmap for future research and development of TPA-DPP-based photovoltaic materials.

Photocatalytic activation of peracetic acid by metal–free C2N3 for efficient water purification under visible light: High–efficiency bifurcated electron transport

Photocatalytic activation of environmental-friendly and lowcost peracetic acid (PAA) is a “green” strategy for wastewater treatment. Herein, C2N3, an allotrope of g-C3N4, was prepared for the first time via a simple calcination. The C2N3/PAA/Vis system was used to degrade sulfamethoxazole (SMX) and inactivate E. coli. The SMX was completed removed within 70 min, and its degradation rate constant was 10 times that of g-C3N4/PAA/Vis system. The system showed excellent degradation performance under wastewater simulation experiments. Electrochemical and EPR experiments verified that C2N3 acted as an electron donor under visible light, and its electrons were transferred to O2 to produce O2–. PAA acted as another electron acceptor and accepted electrons to generate 1O2 via non-radical pathways. This work reveals that high–efficiency bifurcated electron transport processes enhanced the degradation of contaminants and provides a superior metal–free catalyst/matrix-material for further doping to improve the performance in other applications.

Efficient and robust IrW/WO3-x@NC/CP self-standing electrode with low Ir-loading for overall water electrolysis in acidic medium

To further enhance the long-term durability of the cost-effective Ir-based catalysts, some acid-stable oxides are used as supports for acidic OER catalysts. Herein, taking carbon paper (CP) as the substrate, we prepared a self-standing IrW/WO3-x@NC/CP electrode via a layer-by-layer modified method. Among it, N-doped porous C framework not only provides a large specific surface for the attachment of WO3-x, but also makes up for the lack of conductivity of WO3-x and accelerates the electron transport process. The interaction between Ir and W sites in the form of IrW alloy which has generated during the high-temperature calcination and the dispersed Ir in WO3-x matrix improve the intrinsic catalytic activity. And due to the Pt-like effect of W and the tuning role of the electronic structure by the IrW alloy, IrW/WO3-x@NC/CP with an Ir content of only 19.1 µg cm−2 exhibits excellent bifunctional activity in acidic media. To obtain 10 mA cm−2, IrW/WO3-x@NC/CP just needs overpotential of 22 mV (for HER) and 206 mV (for OER) respectively with a mass specific activity of 4.008 A mgIr−1 at 1.55 V. For the whole water splitting, it only requires 1.52 V and 1.70 V to reach 10 mA cm−2 and 100 mA cm−2 respectively, and can operate continuously for over 40 h.

The Unique Fe3Mo3N Structure Bestowed Efficient Fenton-Like Performance of the Iron-Based Catalysts: The Double Enhancement of Radicals and Nonradicals.

Iron-based catalysts are widely used in Fenton-like water pollution control technology due to their high efficiency, but their practical applications are limited by complex preparation conditions and strong blockage of Fe2+/Fe3+ cycle during the reaction. Here, a new iron-molybdenum bimetallic carbon-based catalyst is designed and synthesized using cellulose hydrogel for adsorption of Fe and Mo bimetals as a template, and the effective iron cycle in water treatment is realized. The integrated materials (Fe2.5Mo@CNs) with "catalytic/cocatalytic" performance have higher Fenton-like activation properties and universality than the equivalent quantity iron-carbon-based composite catalysts (Fe@CNs). Through the different characterization methods, experimental verifications and theoretical calculations show that the unique Fe3Mo3N structure promotes the adsorption of persulfate and reduces the energy barrier of the reaction, further completing the double enhancement of radicals (such as SO4·-) and nonradicals (1O2 and electron transport process). The integrated "catalytic/cocatalytic" combined material is expected to provide a new promotion strategy for Fenton-like water pollution control.

Disparate Effects of Two Clerodane Diterpenes of Giant Goldenrod (Solidago gigantea Ait.) on Bacillus spizizenii.

New substances with antimicrobial properties are needed to successfully treat emerging human, animal, or plant pathogens. Seven clerodane diterpenes, previously isolated from giant goldenrod (Solidago gigantea) root, were tested against Gram-positive Bacillus subtilis, Bacillus spizizenii and Rhodococcus fascians by measuring minimal bactericidal concentration (MBC), minimal inhibitory concentration (MIC) and half-maximal inhibitory concentration (IC50). Two of them, Sg3a (a dialdehyde) and Sg6 (solidagoic acid B), were proved to be the most effective and were selected for further study. Bacillus spizizenii was incubated with the two diterpenes for shorter (1 h) or longer (5 h) periods and then subjected to genome-wide transcriptional analyses. Only a limited number of common genes (28 genes) were differentially regulated after each treatment, and these were mainly related to the restoration of cell membrane integrity and to membrane-related transports. Changes in gene activity indicated that, among other things, K+ and Na+ homeostasis, pH and membrane electron transport processes may have been affected. Activated export systems can be involved in the removal of harmful molecules from the bacterial cells. Inhibition of bacterial chemotaxis and flagellar assembly, as well as activation of genes for the biosynthesis of secondary metabolites, were observed as a general response. Depending on the diterpenes and the duration of the treatments, down-regulation of the protein synthesis-related, oxidative phosphorylation, signal transduction and transcription factor genes was found. In other cases, up-regulation of the genes of oxidation-reduction processes, sporulation and cell wall modification could be detected. Comparison of the effect of diterpenes with the changes induced by different environmental and nutritional conditions revealed several overlapping processes with stress responses. For example, the Sg6 treatment seems to have caused a starvation-like condition. In summary, there were both common and diterpene-specific changes in the transcriptome, and these changes were also dependent on the length of treatments. The results also indicated that Sg6 exerted its effect more slowly than Sg3a, but ultimately its effect was greater.

Study of nanosecond pulsed hollow-cathode electron beam generation and transportation based on PIC-MCC simulation

This work employs the PIC-MCC (Particle-in-Cell Monte-Carlo collisions) method to study the nanosecond pulsed electron beam time-varied beam current profiles through the hollow-cathode discharge plasma evolution and electron beam transportation process. The electron beam’s energy and current distribution characteristics at the anode hole are investigated, and the simulation’s grid and step sizes are set as 0.04 µm and 5×10-13s, respectively. Experimental parameters are used in the simulation, and experimental results are also used to verify the simulation accuracy. The simulations investigate the transportation characteristics of the electron beam under different conditions and obtain the effects of voltage, current, and ion density on the distribution characteristics of the electron beam. The electron beam current generated by the hollow-cathode discharge is gradually transformed from a random distribution in the central region to a Gaussian distribution. Due to the ion-forced channel formed by the runaway electron pre-ionization, the high-energy electron beam achieves focused transport over a certain distance, and the high-energy electron beam has a smaller Gaussian radius than the source input. Besides, the ion-focusing channel formed by the high-energy electron transportation process can realize the transportation of the high-current electron beam in the conduction stage.

Photo- and electrochemical properties of newly synthesized thioxathone-viologen-fluorene ternary compound and its electrochromic device

External stimuli-responsive materials exhibit widespread potential applications in sensors, smart windows, displays, and opto-electronic molecular devices. In this study, we report light-/electrochemically induced chromic behaviors of newly synthesized ternary compound in the device. This compound is composed of a light-harvesting unit of thioxathone (TX), an electron donor of fluorene (FL), and an electron mediator of viologen (VIO), and thus it can act as a photochromic species with an intramolecular electron transfer under irradiation. The precursors of TX and FL substituents give off broad emissions at approximately 437 and 310 − 330 nm, respectively. Both emissions are largely quenched in the TX-VIO-FL ternary compound, which is caused by an intramolecular transduction of energy from the excited singlet FL and TX to the electroactive VIO substituent. Based on cyclic voltammogram of TX-VIO-FL modified electrodes, two reversible waves are observed at around − 0.44 and − 0.89 V (vs Hg/Hg2Cl2), attributed to the electron transport processes of TX-VIO2+-FL ↔ TX-VIO+•-FL and TX-VIO+•-FL ↔ TX-VIO0-FL, respectively. Sandwiched type of photo-/electrochromic devices are constructed, displaying a good transmittance and reversible viologen color change behavior under irradiation or an applied bias of − 2.6 V.

The simulation of electron transport of dielectric materials under high-energy electron storms?

When the space high-energy electron storm is generated in the Space Solar Power Station, the high voltage biased on the dielectric materials is a key factor affecting the deep charging process. In this work, the electron transport process in poly-ether-ether-ketone flat plates has been studied by the Geant4 simulation. It is found that the trapped charge density enhances 2-3 orders of magnitude under high-energy electron storms and that the trapped charge density gradually increases with the increase of the radiation time. The number of electrons deposited and charge migration decreases as the shielding thickness increases, while the trapped charge density decreases significantly and its spatial distribution gradually changes to a concave distribution.

Crystal structure, optical characterization, conduction and relaxation mechanisms of a new hybrid compound (C6H9N2)2[Sb2Cl8].

Hybrid materials play a crucial role in the construction of flexible electronic devices due to the advantages of both organic and inorganic components. To this end, a new hybrid compound (C6H9N2)2[Sb2Cl8] was successfully fabricated using the slow evaporation solution growth approach at room temperature. In-depth research has been done on the structural, optical, and dielectric characteristics. This compound adopts the triclinic symmetry and crystallizes in the centrosymmetric space group P1̄. The inorganic and organic components respectively form anionic and cationic layers parallel to the ac-plane and alternate along the crystallographic b-axis. The [Sb2Cl8]2- dimeric units are bound to the 2-amino-5-picolinium cations [(C6H9N2)]+ through N-H⋯Cl hydrogen bonds. Optical absorption measurements showed a semiconductor behavior with a band gap of approximately 3.57 eV. In addition, DFT calculations were performed to investigate the absorption spectrum, wavelength, and HOMO-LUMO gap. The analysis of complex impedance spectra shows that the electrical conductivity of the sample is strongly frequency and temperature dependent, indicating a relaxation phenomenon and semiconductor-type behavior. Dielectric data obtained from complex impedance spectroscopy and ac conductivity with the use of the Maxwell-Wagner equivalent circuit model, and the universal power law have been investigated to explore the basic components of the electronic transport and relaxation process in our material.

Chemical synthesis and super capacitance performance of novel CuO@Cu4O3/rGO/PANI nanocomposite electrode.

Copper oxide-based nanocomposites are promising electrode materials for high-performance supercapacitors due to their unique properties that aid electrolyte access and ion diffusion to the electrode surface. Herein, a facile and low-cost synthesis in situ strategy based on co-precipitation and incorporation processes of reduced graphene oxide (rGO), followed by in situ oxidative polymerization of aniline monomer has been reported. CuO@Cu4O3/rGO/PANI nanocomposite revealed the good distribution of CuO@Cu4O3 and rGO within the polymer matrix which allows improved electron transport and ion diffusion process. Galvanostatic charge-discharge (GCD) results displayed a higher specific capacitance value of 508 F g-1 for CuO@Cu4O3/rGO/PANI at 1.0 A g-1 in comparison to the pure CuO@Cu4O3 278 F g-1. CuO@Cu4O3/rGO/PANI displays an energy density of 23.95 W h kg-1 and power density of 374 W kg-1 at the current density of 1 A g-1 which is 1.8 times higher than that of CuO@Cu4O3 (13.125 W h kg-1) at the same current density. The retention of the electrode was 93% of its initial capacitance up to 5000 cycles at a scan rate of 100 mV s-1. The higher capacitance of the CuO@Cu4O3/rGO/PANI electrode was credited to the formation of a fibrous network structure and rapid ion diffusion paths through the nanocomposite matrix that resulted in enhanced surface-dependent electrochemical properties.

Preparation of high-performance large-area perovskite solar cells by atomic layer deposition of metal oxide buffer layer

Perovskite solar cells have been widely recognized as the most promising new-type photovoltaic device due to its power conversion efficiency rapidly increasing from 3.8% to over 26% in merely fifteen years. However, the high performances are achieved mainly on small area cells with an active area lower than 0.1 cm<sup>2</sup>. When enlarging the active area of perovskite solar cells, the efficiency falls dramatically. So, how to reduce the gap between performances of small area cells and large area cells gradually becomes a critical point in the path towards the commercialization of perovskite photovoltaic technology. Herein, a strategy of pre-growing thin layer of TiO<sub>2</sub> on a rough FTO substrate by atomic layer deposition method before spin-coating SnO<sub>2</sub> nanoparticles is proposed. Due to the inherent conformal film growth mode of atomic layer deposition, the FTO substrate can be completely covered by TiO<sub>2</sub>, thus preventing the direct contact between local protrusions of FTO and perovskite layer and impeding the current leakage phenomenon, which can be verified by the measurements from X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy, and further proved by the dark current measurement. By using this method , the repeatability and consistency of the small area cell fabrication technology on the same substrate are improved obviously. The improved electron transport process revealed by photoluminescence results and incident light management process revealed by external quantum efficiency results also brings about better solar cell performances. More importantly, highly efficient 0.5 cm<sup>2</sup> large area perovskite solar cells are fabricated through optimization of TiO<sub>2</sub> thickness. When growing 200 cycles TiO<sub>2</sub> (~9 nm in thickness) by using atomic layer deposition technology, the champion large area perovskite solar cell possesses a power conversion efficiency as high as 24.8% (certified 24.65%). The device performances also show excellent repeatability between different fabrication batches. The perovskite solar cell with TiO<sub>2</sub> buffer layer deposited on the atomic layer can still retain over 95% of its initial efficiency after having been stored in a nitrogen atmosphere for 1500 h. The technique proposed in this paper can be helpful in manufacturing perovskite solar cell modules in the realistic photovoltaic market and can be extended to the large area fabrication of other perovskite optoelectronic devices such as light emitting diode, laser and detector.

25-26 Ağustos 2018 Jeomanyetik Fırtına Sırasında Afrika Bölgesi Üzerindeki Manyetik Eşlenik Çiftleri Üzerindeki TEC Değişikliklerinin İncelenmesi

In this study, the electron transport process resulting from electromagnetic drift between two magnetic conjugate pairs over the African region during the August 25-26 2018 geomagnetic storm was investigated. The effects of geomagnetic conditions presented with Dst index and IMF Bz values on Total Electron Content (TEC) values at conjugate stations were compared separately for stormy and quiet periods. During the storm period, the effect of TEC values at stations in the northern hemisphere (Haifa and Djibouti) on the TEC values at stations in the southern hemisphere (Ambalavao and Malindi) is greater than the effect of TEC values in the southern hemisphere on TEC values in the northern hemisphere. According to this result, it can be said that the south-directed electromagnetic convection was more than the north-directed convection in the examined dates. When the coefficients are examined, it can be said that the interaction is more in the magnetic conjugate pair that is closer to the equator during the storm period, and the interaction is more in the magnetic conjugate pair that is far from the equator during the silent period. Considering the coefficients calculated for Dst and IMF Bz, it is seen that the TEC values are very small compared to their coefficients. From this it can be concluded that the effect of Dst and IMF Bz is much smaller than the effect of TEC values at a station on TEC values at its magnetic conjugates.

Properties of Indium Antimonide Nanocrystals as Nanoelectronic Elements

By measurements on single nanocrystals of indium antimonide in the interelectrode nanogap of a scanning probe microscope, current-voltage characteristics with quasiperiodic current pulsations, are explained in the model of Bloch oscillations in a perfect nanocrystal, and individual sharp peaks - conductivity resonances, explained in the model of quantum-size limitation of the wave process of electron transport in a deep potential hole. The mutual influence of radiation from two statistical ensembles of nanocrystals from the same batch was experimentally studied and established. It is assumed that this radiation is entangled photons. It is proposed to use nanocrystals in nanoelectronics as a single-electron memristor, a single-photon bolometer, and a source of microwave radiation.

Polysaccharides derived from Ganoderma lucidum applied to the extraction chitosan and development of electrochemical sensor based on extracted chitosan and graphitic carbon nitride modified electrode for determination nitrite in food samples

The current study focused on extracting chitosan from polysaccharides generated from Ganoderma lucidum and applying it to the construction of electrochemically modified electrodes based on graphitic carbon nitride (g-C3N4) for the measurement of nitrite in water and food samples. Ganoderma Lucidum polysaccharides were isolated and characterized. The chitosan was then isolated enzymatically from the polysaccharides using a chemical technique. The isolated chitosan and g-C3N4 were used to modify a GCE (chitosan/g-C3N4/GCE). The structural investigations employing FT-IR, SEM, and XRD show that chitosan successfully interacted with g-C3N4 in the chitosan/g-C3N4 sample. Electrochemical evaluation using cycle voltammetry (CV), differential pulse voltammetry (DPV), and amperometry revealed that the chitosan/g-C3N4/GCE electrode has good sensitivity and selectivity for determining nitrite. The use of chitosan and g-C3N4 in electrode surface modification improved nitrite electro-oxidation performance by allowing for more effective adsorption and electron transport processes. DPV measurement showed that the sensor had a sensitivity of 0.12103 μA/μM, a linear range of 40 to 2000 μM, and a limit of detection of 21 nM, and amperometry measurement showed the sensor's sensitivity of 0.15487 μA/μM, linear range of 20 to 4230 μM, and an LOD of 10 nM. These findings indicated a more sensitive and wide range of sensor performance using amperometry with respect to the DPV technique. The method's validity and accuracy in determining nitrite in prepared genuine samples (water, milk, apple juice, orange juice, Aloe vera, and tomato juice) were investigated. RSD values (3.19 % to 4.75 %) and recovery values (80.00 % to 98.33 %) were found to be satisfactory. The data also revealed that there were no substantial matrix interferences, demonstrating the accuracy and applicability of the proposed approach for detecting nitrite in food samples. Therefore, the proposed sensor design has several advantages that make it a promising candidate for various applications. Its reusability, stability, wide linear range, accuracy, and low cost make it an attractive option for many industries.

Electrochemical activation of peroxydisulfate by Ti/IrTaO2 anode for quick degradation of xanthate

High concentrations of residual xanthate in mineral processing wastewater often limit the reuse of tailing water. Targeted removal of xanthate is an effective strategy for improving the tailing water recycling rate. In this study, the degradation efficiency and mechanism of sodium ethyl xanthate (SEX) in an electroactivated peroxydisulfate (EAPDS) system were investigated systematically. To avoid the influence of co-existing organic and inorganic matters in real flotation wastewater, we used simulated SEX wastewater to conduct the efficiency and mechanism investigation. A significant synergistic effect between electrocatalysis and peroxydisulfate was observed during the SEX decomposition. When the initial concentration of SEX was 200 mg/L, it achieved 100% removal rate only in 30 min with PDS dosage of 5 mM at current density of 10 mA/cm2. The introduction of peroxydisulfate boosted the removal efficiency six-fold compared to electrocatalysis alone. UV-Vis spectroscopy and GC-MS analyses revealed that the intermediate products of SEX were C2H5OH and CS2. The reactive oxygen species induced in the EAPDS were identified using a series of detection methods. •OH, 1O2, h+, O2•− and electron transportation process (ETP) all contributed to SEX removal. The degradation mechanism in the EAPDS system was proposed based on the analysis of the reactive oxygen species and products. Application to real flotation wastewater was attempted as well. The effects of different operating conditions were also evaluated, including pH, coexisting anions, PDS dosage, and current density. This study provides a new approach for the rapid removal of residual xanthates from mineral processing wastewater.

Comparison of Computational Strategies for the Calculation of the Electronic Coupling in Intermolecular Energy and Electron Transport Processes.

Electronic couplings in intermolecular electron and energy transfer processes calculated by six different existing computational techniques are compared to nonorthogonal configuration interaction for fragments (NOCI-F) results. The paper addresses the calculation of the electronic coupling in diketopyrrolopyrol, tetracene, 5,5'-difluoroindigo, and benzene-Cl for hole and electron transport, as well as the local exciton and singlet fission coupling. NOCI-F provides a rigorous computational scheme to calculate these couplings, but its computational cost is rather elevated. The here-considered ab initio Frenkel-Davydov (AIFD), Dimer projection (DIPRO), transition dipole moment coupling, Michl-Smith, effective Hamiltonian, and Mulliken-Hush approaches are computationally less demanding, and the comparison with the NOCI-F results shows that the NOCI-F results in the couplings for hole and electron transport are rather accurately predicted by the more approximate schemes but that the NOCI-F exciton transfer and singlet fission couplings are more difficult to reproduce.

A simple strategy passivating ZnO electron transport layers for realizing high efficiency in organic solar cells

Sol–gel processed ZnO films are widely used as electron transport layers (ETLs) in organic solar cells (OSCs). However, defects caused by COOH, OH, and vacancies of oxygen in ZnO ETLs are harmful for electron extraction and transport processes in OSCs. Here, a simple and effective strategy is reported to passivate free OH via hydrogen bond of HO…NH2. A small molecule of biuret is introduced into ZnO precursor as an additive to form ZnO films. The hydrogen bond of HO…NH2 is confirmed by XPS and FT-IR in this study, which passivates traps originated from free OH. The passivated ZnO ETLs exhibit better morphology and higher electron mobility than pristine ZnO ETLs. In OSCs with fullerene and non-fullerene light absorbers, the cells with biuret-doped ZnO ETLs obtain improved power conversion efficiency (PCE), which prove the generality of biuret doped ZnO ETLs. Eventually, a maximal PCE of 18.19 % is obtained when PM6:L8-BO is selected as light absorber. Furthermore, the contributions of biuret are discussed in this work.