Active Layer Research Articles

An Efficient and Stable Inverted Structure Organic Solar Cell Using ZnO Modified by 2D ZrSe2 as a Composite Electron Transport Layer

AbstractAs an electron transport layer (ETL) widely used in organic solar cells (OSCs), ZnO has problems with energy level mismatch with the active layer and excessive defects on the ZnO surface, which can reduce the efficiency of OSCs. Here, ZnO/ZrSe2 composite is fabricated by modifying ZnO with 2D ZrSe2. The XPS and first‐principles calculation (FPC) show that ZnO obtains electrons from ZrSe2 and forms interfacial dipoles toward the active layer, which decreases the work function of ZnO, thus reducing the interface barrier and favoring the collection of electrons in OSCs. At the same time, after ZrSe2 modification, the oxygen vacancy density on the ZnO surface decreases, thus improving the conductivity of ZnO. More importantly, the femtosecond transient absorption (Fs‐TA) shows that ZrSe2 selectively traps holes from the active layer, which prevents the holes from entering the ZnO, thereby reducing the probability of electron recombination. Finally, ZnO/ZrSe2 composite is used as a novel ETL in OSCs with PBDB‐T: ITIC, PM6:Y6 and PM6: L8‐BO as active layers, and obtaining 12.09%, 16.34%, and 18.24% efficiency, respectively. This study provides a method for the interface modification of ZnO, and further investigates the role of 2D nanosheets in the interface modification.

Tactic of A−D−A scheme organic photocatalyst with broad spectral feature of absorption enables photocatalytic performance improvement

Breakthrough in organic pollutant photodegradation is achieved by linking the photocatalysis technology with the excellent photovoltaic nature of bulk heterojunction organic solar cell (BHJ-OSC) active layers. The first pure organic photocatalytic system built to degrade methylene blue (MB)-laden water by associating biochar supporter with active layers, fabricating a subset of organic photocatalysts, it is the first result of A−D−A scheme to date. The champion catalyst C-PM6:TPA-PDI:PIID-ClBF with excellent wide absorption spectra and fine tunable energy level exhibits greater potential in solar harvesting and prolonging charge lifetime, as well as high reusability and no insoluble residuals after treatment. As a result, this strategy both benefits the production of reactive oxygen species and eliminates concerns regarding insoluble residuals, subtly coping with the common disadvantages of most existing photocatalysts. The C-PM6:TPA-PDI:PIID-ClBF successfully degraded MB with a remarkable efficiency of 100 % achieved in 12 min, while also can maintain this high efficiency for up to 100 cycles, as long as the active materials remain active. These findings step forward in developing photocatalysts that are environmentally friendly and affordable, elucidating significant implications of advancing series of BHJ-OSCs-like photocatalysts for the removal of organic pollutants.

Improved device performance with 4-amino-TEMPO derivatives for fiber dye-sensitized solar cells and organic light-emitting diodes

4-Amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-Amino-TEMPO; 4AT), has been used as a photo-catalyst to boost photo-catalytic activity, are a promising approach for improving the efficiency of fiber-shaped dye-sensitized solar cells (FDSSCs) and fiber-shaped organic light-emitting diodes (FOLEDs). Herein, one of the 4AT, 4-p-toluenesulfonamide-TEMPO (ATpTS) was successfully synthesized by using a dropwise method. The synthesized ATpTS showed an extraordinary photo-catalytic effect and significantly enhanced performance compared to the pristine-based active layer for both solid-state electrolytes of the FDSSCs (SS-FDSSCs) and FOLEDs. Briefly, a power conversion efficiency increment of 22.8% is recorded for the ATpTS-enhanced SS-FDSSCs; whereas an external quantum efficiency increment of 45.4% is achieved for the ATpTS-enhanced FOLEDs.

Investigation of Perovskite Solar Cells Using Guanidinium Doped MAPbI3 Active Layer.

In this work, guanidinium (GA+) was doped into methylammonium lead triiodide (MAPbI3) perovskite film to fabricate perovskite solar cells (PSCs). To determine the optimal formulation of the resulting guanidinium-doped MAPbI3 ((GA)x(MA)1-xPbI3) for the perovskite active layer in PSCs, the perovskite films with various GA+ doping concentrations, annealing temperatures, and thicknesses were systematically modulated and studied. The experimental results demonstrated a 400-nm-thick (GA)x(MA)1-xPbI3 film, with 5% GA+ doping and annealed at 90 °C for 20 min, provided optimal surface morphology and crystallinity. The PSCs configured with the optimal (GA)x(MA)1-xPbI3 perovskite active layer exhibited an open-circuit voltage of 0.891 V, a short-circuit current density of 24.21 mA/cm2, a fill factor of 73.1%, and a power conversion efficiency of 15.78%, respectively. Furthermore, the stability of PSCs featuring this optimized (GA)x(MA)1-xPbI3 perovskite active layer was significantly enhanced.

Versatile Self‐Assembled Monolayer Material Enables Efficient Organic Photovoltaic Devices and Modules

AbstractEfficient and stable hole transport layer (HTL) is an important component of organic photovoltaics (OPV). Herein, a novel self‐assembled monolayer material of 4PADCB (short for (4‐(7H‐dibenzo[c,g]carbazol‐7‐yl)butyl)phosphonic acid) as HTL for non‐fullerene (NF) OPV is reported. Compared to the widely used PEDOT:PSS HTL, the usage of 4PADCB not only enhances photon incident and charge generation but also effectively improves the morphology of the upper active layer, promotes molecular packing, and balances the carrier transport within active layer. As a result, the single‐junction binary D18:L8BO OPV, employing 4PADCB as HTL, achieves a high‐power conversion efficiency (PCE) of 19.02% with excellent storage stability. Furthermore, a 19.3 cm2 OPV module comprising seven sub‐cells demonstrates a maximum PCE of 15.44%, which is the highest value of reported efficiency for large‐area binary OPV modules. Meanwhile, the module is the first demonstration of an OPV module based on self‐assembled monolayer material. This work underscores the substantial potential for the application of 4PADCB in efficient NF OPV devices and high‐throughput large‐area modules.

Distance-guided domain adaptation for bearing fault diagnosis under variable operating conditions

Abstract Transfer learning (TL) has demonstrated effective application in diagnosing bearing faults under varying operating conditions. The current TL methods achieve domain alignment by minimizing the variation in the marginal distribution of data between the source and target domains in the feature space. However, this approach yields incomplete similarity, leading to domain shift and a decrease in diagnostic performance. To overcome this problem, this paper proposes a new distance-guided domain adaptation (DGDA) method that consists of two modules: Deep domain adaptive correlation alignment (Deep CORAL) combined with Joint Maximum Mean Discrepancy (JMMD) for guided domain adaptation. Deep CORAL employs nonlinear transformations to synchronize second-order statistical correlations across source and target domains, thus ensuring feature-level alignment between these domains. JMMD is utilized to align the joint distribution of input features and output labels within the activation layer in the deep network, thereby bolstering domain alignment. Building on this, we propose a network structure that merges ResNet and BiLSTM, powered by wavelet kernels, serving as a feature extractor. This structure is designed to learn domain-invariant features and incorporates attention mechanisms to amplify important information while diminishing the impact of redundant data. An analysis of bearing experiments is used to demonstrate the effectiveness of this method, and the proposed method significantly outperforms several popular methods in diagnostic performance.

Crystallization‐Driven Optimization of Morphology and Performance in Near‐Infrared Organic Photodetectors via Alkyl Side Chain Tuning of Narrow Bandgap Non‐Fullerene Acceptors

AbstractNarrow bandgap non‐fullerene acceptors (NBG NFAs) are crucial in advancing near‐infrared organic photodetectors (NIR OPDs). However, the polymorphous behavior of NFAs introduces energetic disorder and charge‐trapping sites in the bulk heterojunction (BHJ) active layers, thereby hindering the NIR performance of OPDs. This study demonstrates the design and optimization of the molecular structures of alkyl side chains in NFAs to morphologically address these electrical limitations and shed light on how side chains affect the crystallization‐driven control of the morphogenesis process in BHJ layers. The structure, linearity, and length of the alkyl side chain molecules are strategically designed and controlled to synthesize a series of NBG NFAs, namely COT‐R (R = EH, BO, Oct, or Dod). The in‐depth quantitative investigations into the morphological and electrical factors reveal that side‐chain optimization effectively enhances various morphological properties, such as the molecular alignment and compatibility between components in the BHJ layer, resulting in the mitigation of energetic disorders and charge traps in the BHJ layers. Therefore, the optimized BHJ system, comprising COT‐Oct blended with PTB7‐Th, achieves a reduced dark current and increased responsivity, contributing to the development of high‐performance NIR OPDs with an impressive specific detectivity of 1.49 × 1012 Jones at 1000 nm under ‐0.5 V.

Enhanced properties of a positive-charged nanofiltration membrane containing quaternarized chitosan through second interfacial polymerization for the removal of salts and pharmaceuticals.

Nanofiltration (NF) membrane technology has been widely used in the removal of salts and trace organic pollutants, such as pharmaceuticals and personal care products (PPCPs), due to its superiority. A positive-charged composite NF membrane with an active skin layer was prepared by polyethyleneimine (PEI), trimethyl benzene chloride, and quaternate chitosan (HTCC) through second interfacial polymerization on the polyethersulfone ultrafiltration membrane. The physicochemical properties of the nanocomposite membrane were investigated using surface morphology, hydrophilicity, surface charge, and molecular weight cut-off (MWCO). The influence of the concentration and reaction time of PEI and HTCC was documented. The optimized membrane had a MWCO of about 481 Da and possessed a pure water permeability of 25.37 L·m-2·h-1·MPa-1. The results also exhibited salt rejection ability as MgCl2 > CaCl2 > MgSO4 > Na2SO4 > NaCl > KCl, showing a positive charge on the fabricated membrane. In addition, the membrane had higher rejection to atenolol, carbamazepine, amlodipine, and ibuprofen at 89.46, 86.02, 90.12, and 77.21%, respectively. Moreover, the anti-fouling performance and stability of the NF membrane were also improved.

Electrolyte Influence on Properties of Ultra-Thin Anodic Memristors on Titanium

Titanium anodic memristors were prepared in phosphate buffer (PB) and citrate buffer (CB) electrolytes. Studying their I-U sweeps, the memristors presented self-rectifying and volatile behaviors. Transmission electron microscopic analysis revealed crystalline protrusions inside a semi-crystalline Ti oxide. Grounded in this, a hybrid interfacial memristive switching mechanism relaying on partial filaments was proposed. Moreover, both analyzed memristor types demonstrated multilevel switching capabilities. The memristors anodized in the PB and CB showed high-to-low resistance ratios of 4 × 104 and 1.6 × 102, respectively. The observed (more than two order of magnitude) ratio improvement of the PB memristors suggests their better performance, in spite of their modestly high resistive state instabilities, attributed to the thermal stress caused by consecutive switching. The endurance and retention of both the PB and CB memristors was measured over up to 106 cycles, indicating very good lifetimes. Phosphate incorporation into the anodic oxide was confirmed by photoelectron spectroscopy analysis and was related to the improved memristive behavior of the PB sample. The presence of phosphate inside the memristively active layer modifies the availability of free O species (vacancies and ions) in the oxide. Taking all this into consideration, Ti anodic memristors anodized in PB are emphasized as candidates for neuromorphic computing.

Enhancing electrochemiluminescence intensity through emission layer control

Electrochemiluminescence (ECL), an intriguing luminescent phenomenon induced by electrochemical stimulation, has evolved from studying electron transfer reactions to a powerful analytical method and imaging technique. ECL can be generated through annihilation or co-reactant methods, with recent advancements integrating it into imaging devices for diverse applications. This review traces the evolution of ECL from its early applications to recent developments in imaging technology. Notably, the utilization of charge-coupled devices (CCD) and electron multiplying charge-coupled devices (EMCCD) in ECL microscopy has revolutionized imaging capabilities, making it a cost-effective option for point-of-care testing. The review explores the heterogeneous ECL mechanism, emphasizing its limitations and challenges in visualizing objects away from the electrode surface. The synergy between ECL and microscopy is highlighted, showcasing its diverse applications and contributions to understanding ECL mechanisms and improving its use in biological contexts. Finally, the review encapsulates innovative approaches in material design, surface modification, and electrode architecture, providing a comprehensive overview of strategies to control the active layer of the ECL and advance ECL microscopy.

Role of the ZnO electron transport layer in PbS colloidal quantum dot solar cell yield.

The development of lead sulfide (PbS) colloidal quantum dot (CQD) solar cells has led to significant power conversion efficiency (PCE) improvements in recent years, with record efficiencies now over 15%. Many of the recent advances in improving PCE have focused on improving the interface between the PbS CQD active layer and the zinc oxide (ZnO) electron transport layer (ETL). Proper optimization of the ZnO ETL also increases yield, or the percentage of functioning devices per fabrication run. Simultaneous improvements in both PCE and yield will be critical as the field approaches commercialization. This review highlights recent advances in the synthesis of ZnO ETLs and discusses the impact and critical role of ZnO synthesis conditions on the PCE and yield of PbS CQD solar cells.

Spontaneous Formation of 1D/3D Perovskite Heterojunctions for Efficient Inverted Perovskite Solar Cells

AbstractInterfacial modification is a key strategy for improving the performance of perovskite photovoltaic devices. While the modification of the top surface of the perovskite active layer is well established, engineering of the buried interface is highly challenging. Here, the spontaneous formation of a 1D/3D perovskite heterojunction at the buried interface of a perovskite active layer by incorporating choline acetate alongside the perovskite precursors is reported. Importantly, extensive spectroscopic and microscopic characterization and solid‐state nuclear magnetic resonance experiments demonstrate the formation of phase‐pure 1D and 3D domains. The 1D/3D junction results in a suppression of the defect states and an improved energetic level alignment at the buried interface, leading to a maximum power conversion efficiency of >24% when incorporated in inverted architecture perovskite solar cells. This work introduces a versatile approach to the modification of the buried interface of the perovskite active layer.

Multi‐site Passivation of ZnO Metal Oxides via Biomolecules for Efficient and Highly Stable Organic Solar Cells

Comprehensive SummaryZnO nanoparticles (nps) among metal oxide (MOs) are proven to be essential electron transporting layers (ETLs) applied in organic solar cells (OSCs). However, intrinsic defects, interfacial charge recombination, and catalytic behavior towards the active layer restrict the applications of ZnO nps for efficient and long‐term stable OSCs. The commonly available biomolecule cytidine 5'‐monophosphate (CMP‐OH) with phosphonic acid, its salt cytidine 5'‐monophosphate disodium salt (CMP‐ONa) with a phosphate group as an anchoring group and conjugated terminal functional in both analogous molecules provide carrier transfer bridge at bottom interface of the active layer. Systematized theoretical investigations and characterizations have discovered the multi‐site coordination of CMP‐OH towards acceptor molecules and ZnO nps. The dual‐side alignment of CMP analogous molecules hinders interfacial charge recombination and enhances charge transfer potential at once. Inevitably, PM6:L8‐BO‐based OSCs with modified ETL obtain 18.13% efficiency, 12% higher than that of unmodified nps. Besides higher efficiency, CMP‐OH‐based OSC devices illustrate remarkably improved thermal stability for 500 h at 85 °C with 72% of initial PCE and operation stability for 2000 h with 90.1% of initial PCE. This work reveals the passivation mechanism of multi‐anchoring groups towards MOs and single‐functional groups towards the active layer to optimize the interface for efficient and highly stable OSCs.

Poling induced changes in polarization domain structure of polymer ferroelectrics for application in organic thin film transistors

While electrical poling of organic ferroelectrics has been shown to improve device properties, there are challenges in visualizing accompanying structural changes. We observe poling induced changes in ferroelectric domains by applying differential phase contrast (DPC) imaging in the scanning transmission electron microscope, a method that has been used to observe spatial distributions of electromagnetic fields at the atomic scale. In this work, we obtain DPC images from unpoled and electrically poled polyvinylidene fluoride trifluorethylene films and compare their performance in polymer thin film transistors. The vertically poled films show uniform domains throughout the bulk compared to the unpoled film with a significantly higher magnitude of the overall polarization. Thin film transistors comprising a donor–acceptor copolymer as the active semiconductor layer show improved performance with the vertically poled ferroelectric dielectric film compared with the unpoled ferroelectric dielectric film. A poling field of 80–100 MV/m for the dielectric layer yields the best performing transistors; higher than 100 MV/m is seen to degrade the transistor performance. The results are consistent with a reduction in deleterious charge carrier scattering from ferroelectric domain boundaries or interfacial dipoles arising from electrical poling.

A comparative study with vermifilter and geofilter for domestic wastewater treatment and its Phyto-toxicity efficacy

The present study investigated the role of earthworms in pollutant removal and toxicity assay of domestic wastewater. An indigenous reactor (vermigratings as an active layer) was set up for 60 days with a hydraulic loading rate of 1 m3 / m2 -d and hydraulic retention time of 3.5 h to evaluate its performance. Removal of total suspended solids, total dissolved solids, biochemical oxygen demand, chemical oxygen demand, and sulfate was found to be 92 %, 93 %, 89 %, 86 %, and 63.43 %, respectively. The Phyto-toxicity test reveals a higher germination rate and plant growth with vermifilter effluent than with geofilter effluent and raw wastewater. Additionally, vermifilter achieved heterotrophic bacteria removal by 1.54-fold. Hence, treated effluent can be used for irrigation purposes. Overall, this study will establish a potential alternative to the conventional wastewater treatment system and achieve Sustainable Development Goals 6.

Mitigating ash-related alkali and heavy metals emissions in rotary kiln through oxygen-carrier-aided combustion of waste

Rotary kiln (RK) incineration technology gains prominence in waste management, aiming to reduce pollution, recover energy, and minimize waste. Oxygen-carrier (OC)-aided incineration of waste in the RK demonstrates notable benefits by enhancing oxygen distribution uniformity and facilitating fuel conversion. However, the effects of OC on ash-related alkali and heavy metals during waste incineration in the RK remain unknown. In this study, manganese ore and ilmenite as OCs are introduced into RK during waste combustion, focusing on their effects on the bottom ashes and the behavior of alkali and heavy metals. Results show that manganese ore exhibits a decreasing reactivity due to oxygen depletion during the conversion from Mn2O3 to Mn3O4, while ilmenite maintains good reactivity due to sustained enrichment of Fe2O3 on the particles even after multiple cycles in RK. The porous structure on the surface of OCs particles verifies the cyclic reaction involving oxidation by air and reduction by fuel as OCs move between the active and passive layers of the bed. The porous OCs particles offer abundant adsorption sites for K from the gaseous phase, with surface-deposited K migrating into the particles and enhancing the OCs' capacity for K adsorption. Adding OCs promotes the formation of stable, less volatile compounds of heavy metals (As, Cr, Pb, and Zn) and enhances their retention in bottom ash while ensuring the leaching toxicity remains below Chinese national standard limits. This study enhances the understanding of OCs in incineration, guiding vital references for waste management practices and environmental sustainability.

Heterogeneous Nucleating Agent for High-Boiling-Point Nonhalogenated Solvent-Processed Organic Solar Cells and Modules.

High-boiling-point nonhalogenated solvents are superior solvents to produce large-area organic solar cells (OSCs) in industry because of their wide processing window and low toxicity; while, these solvents with slow evaporation kinetics will lead excessive aggregation of state-of-the-art small molecule acceptors (e.g. L8-BO), delivering serious efficiency losses. Here, a heterogeneous nucleating agent strategy is developed by grafting oligo (ethylene glycol) side-chains on L8-BO (BTO-BO). The formation energy of the obtained BTO-BO; while, changing from liquid in a solvent to a crystalline phase, is lower than that of L8-BO irrespective of the solvent type. When BTO-BO is added as the third component into the active layer (e.g. PM6:L8-BO), it easily assembles to form numerous seed crystals, which serve as nucleation sites to trigger heterogeneous nucleation and increase nucleation density of L8-BO through strong hydrogen bonding interactions even in high-boiling-point nonhalogenated solvents. Therefore, it can effectively suppress excessive aggregation during growth, achieving ideal phase-separation active layer with small domain sizes and high crystallinity. The resultant toluene-processed OSCs exhibit a record power conversion efficiency (PCE) of 19.42% (certificated 19.12%) with excellent operational stability. The strategy also has superior advantages in large-scale devices, showing a 15.03-cm2 module with a record PCE of 16.35% (certificated 15.97%).

Eliminating the Burn-in Loss of Efficiency in Organic Solar Cells by Applying Dimer Acceptors as Supramolecular Stabilizers.

The meta-stable active layer morphology of organic solar cells (OSCs) has been identified as the main cause of the rapid burn-in loss of power conversion efficiency (PCE) during long-term device operation. However, effective strategies to eliminate the associated loss mechanisms from the initial stage of device operation are still lacking, especially for high-efficiency material systems. Herein, we report the introduction of molecularly engineered dimer acceptors with adjustable thermal transition properties into the active layer of OSCs to serve as supramolecular stabilizers for regulating the thermal transitions and optimizing the crystallization of the absorber composites. By establishing intimate π-π interactions with small-molecule acceptors, these stabilizers can effectively reduce the trap-state density (Nt) in the devices to achieve excellent PCEs over 19%. More importantly, the low Nt associated with an initially optimized morphology can be maintained under external stresses to significantly reduce the PCE burn-in loss in devices. Our research reveals a judicious approach to improving OPV stability by establishing a comprehensive correlation between material properties, active-layer morphology, and device performance, for developing burn-in-free OSCs. This article is protected by copyright. All rights reserved.

Tweaking the Non-Volatile Write-Once-Read-Many-Times (WORM) Memory using Donor-Acceptor Architecture with Isatin as Core Acceptor.

Organic memory devices have attracted attention because they promise flexible electronics, low manufacturing costs, and compatibility with large-scale integration. A series of new D-A architectures were synthesized employing different donor groups and the isatin moiety as the acceptor through Suzuki-Miyaura coupling reactions. Strong intramolecular interactions were observed in the synthesized compounds, further corroborated by an optimal bandgap. The SEM investigation confirmed good molecular ordering and superior thin film surface coverage. All the compounds demonstrated notable binary Write-Once-Read-Many-Times (WORM) memory behaviour. The threshold switching voltage for these D-A systems ranged from -0.79 to -2.37 V, with the compound having isobutyl substituent showing the lowest threshold voltage and maximum ON/OFF ratio of 102, thus outperforming others. The combined effects of charge transfer and charge trapping are responsible for the resistive switching mechanism prevailing in these systems. The alterations in D-A molecules that affect molecular packing, thin film morphology, and, finally, the memory performance of the active layer are highlighted in this work.

Core‐Shell Architectured Sulfur Coated α‐Fe2O3 Nano‐Sheet Anode for Li‐Ion Battery with Insitu Active Solid Electrolyte Interfacial Layer and Li‐Sulfur Energy Storage Systems

AbstractA versatile approach is achieved through the surface coating of sulfur on α‐Fe2O3 nanosheet by microwave treatment that inherently supports the formation of self‐induced active solid electrolyte interface (SEI) layer which effectively protects the electrode surface and enhances the cyclic stability of lithium‐ion battery. The present findings on a sulfur‐coated α‐Fe2O3@S‐2 core‐shell structured anode demonstrates an initial specific capacity of 1194 mAh g−1 at a 0.1 C rate, and an average discharge capacity of 518 mAh g−1 over 20 cycles. Sulfur coating proves the incredible development of an active SEI layer that prevents electrolyte decomposition and the electrode persuades with stable capacity, fast rate capability and retains excellent coulombic efficiency for 500 cycles in LIB. GITT measurements exhibit superior Li+ ion diffusion coefficient 2.87×10−10 cm2 s−1 at 80 % SOC for the α‐Fe2O3@S‐2 electrode. The in‐depth ex‐situ evaluations uncovered a fascinating self‐assembled active Li2SO4 electrode‐electrolyte interface formation in the sulfur‐coated α‐Fe2O3 electrode that contributes interfacial kinetics. The sulfur coated α‐Fe2O3 electrode exhibits an exceptional high‐rate performance and coulombic efficiency even in lithium‐sulfur battery. This research overthrows sulfur‘s significance in forming an active interfacial bridging SEI layer that facilitates lithium‐ion kinetics across the interface and alleviates undesirable SEI development.