Search Results (547)

Benefiting from the booming development of self-assembled monolayer (SAM) based hole-transporting materials, inverted perovskite solar cells (PSCs) have attained a certified power conversion efficiency (PCE) beyond 27.0%, exhibiting great potential for commercialization. However, conventional SAM molecules are prone to self-aggregation owing to their inherent molecular configurations, which readily induced defective and inhomogeneous deposition. In addition, state-of-the-art SAM-based hole-transporting layers are generally deposited in inert environments, while the ambient moisture is expected to further deteriorate the homogeneity of the SAM layers. In this work, a mixed-solvent system of ethanol/N,N-dimethylformamide (DMF) was adopted for the deposition of Me-4PACz SAMs in ambient conditions, which enables significant suppression of intermolecular aggregation in precursor solution and moisture-induced inhomogeneity. The high-quality homogeneous SAM-based hole-transporting layers, along with subsequently optimized perovskite buried interface properties, further empower a prominent increase in the PCE of inverted PSC devices up to 25.0%. Full article

This study investigates the enhancement of electrical conductivity in poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) thin films through the incorporation of few-layer graphene (mG). Nanocomposite films were prepared by spin coating from liquid dispersions containing approximately 10 wt% mG. The resulting films exhibited high optical transmittance (~80%) and significantly reduced sheet resistance, reaching values as low as 1.8 kΩ/□. These improvements in electrical and optical performance are attributed to enhanced charge transport arising from π–π interactions between graphene and PEDOT:PSS, as well as conformational changes in the polymer chains. The PEDOT:PSS/mG composites were successfully applied both as conductive inks, forming conductive trails capable of powering a light-emitting diode (LED), and as hole transport layers in organic light-emitting diodes (OLEDs). Comprehensive optical and electrical characterization of the composite films and the corresponding OLED devices demonstrates the strong potential of PEDOT:PSS/mG nanocomposites for use in flexible and printed electronic applications. Full article

CuSCN is a low-cost inorganic HTL with potentially better ambient stability than Spiro-OMeTAD according to literature. This study explores copper(I) thiocyanate (CuSCN) as a hole transport layer (HTL) to replace the conventional organic material Spiro-OMeTAD in antimony selenosulfide (Sb₂(S,Se)₃) solar cells. Numerical simulations performed with the Afors-het software reveal that the device structure FTO/CdS/Sb₂(S,Se)₃/CuSCN/Au incorporating CuSCN achieves improved interfacial energy band alignment. Specifically, the valence band offset (VBO) is reduced to −0.2 eV, which substantially enhances hole extraction efficiency and suppresses interface recombination. Through systematic optimization of key structural parameters, including the absorber layer thickness (350 nm), the CuSCN layer thickness (9 nm), and its p-type doping concentration (10¹⁹ cm⁻³), the device attains a maximum power conversion efficiency (PCE) of 12.03%. This work provides a theoretical foundation and a viable device design strategy for developing low-cost, highly stable, and efficient Sb₂(S,Se)₃ solar cells. Full article

Interfacial defect passivation has emerged as a critical strategy for mitigating non-radiative recombination losses in inorganic perovskite solar cells (PSCs). However, the distinct chemical environments at the bottom (hole-transport layer) and top (electron-transport layer) interfaces demand passivation agents with tailored functionalities—a principle that remains largely underexplored. Herein, we systematically employed two organic ammonium iodide salts, phenylethylammonium iodide (PEAI) and 2-thiophenemethylammonium iodide (ThMI), to separately modulate the bottom NiO_x/CsPbI₂Br and top CsPbI₂Br/PCBM interfaces of inverted PSCs with a configuration of ITO/NiO_x/CsPbI₂Br/PCBM/BCP/Ag. We reveal different interfacial modulation effects: bottom-interface modification by both PEAI and ThMI dramatically improves the fill factor (FF), with PEAI delivering a more pronounced enhancement due to improved interfacial contact and reduced series resistance. However, top-interface passivation effectively boosts the open-circuit voltage (V_oc), where ThMI exhibits superior voltage elevation capability over PEAI by neutralizing undercoordinated Pb²⁺ defects via its thiophene moiety. Capitalizing on this complementary selectivity, we construct an asymmetric dual-interface passivation architecture with PEAI at the bottom and ThMI at the top (ITO/NiO_x/PEAI/CsPbI₂Br/ThMI/PCBM/BCP/Ag), which synergistically enhances both FF and V_oc. Consequently, the optimized PEAI/ThMI device achieves a champion power conversion efficiency (PCE) of 15.44%, with a V_oc of 1.15 V, a J_sc of 16.34 mA/cm², and an FF of 82.15%, significantly outperforming the control device (11.79%). This work establishes a rational design paradigm for interface-specific passivation in inverted inorganic PSCs, highlighting the importance of molecular functionality in addressing distinct interfacial recombination pathways. Full article

The performance of inverted CH₃NH₃GeI₃ (MAGeI₃) perovskite solar cells incorporating both a hole transport layer (HTL) and an electron transport layer (ETL) was investigated using the Solar Cell Capacitance Simulator (SCAPS). Three candidate HTLs, including PEDOT:PSS, MoS₂, and WS₂, along with five ETLs including PCBM, TiO₂, IGZO, ZnO, and SnO₂, have been systematically evaluated. The analysis shows that WS₂ and SnO₂ provided the most favorable hole and electron transport, respectively. To improve device efficiency, the absorber layer thickness, defect density in MAGeI₃, doping levels of WS₂ and SnO₂, as well as the interface defect densities and the work function of indium tin oxide (ITO), have been systematically studied. The optimal absorber layer thickness is determined to be approximately 900 nm. The optimal doping density of both WS₂ and SnO₂ is 1 × 10¹⁹ cm⁻³. The MAGeI₃ layer should maintain a defect density as low as 1 × 10¹⁵ cm⁻³, and the defect densities at MAGeI₃ interfaces should remain at 1 × 10¹⁵ cm⁻². Additionally, an ITO work function of at least 5.2 eV is necessary to prevent the formation of a Schottky barrier at the ITO/WS₂ interface. The simulated power conversion efficiency (PCE) can reach 22.9% under these optimized conditions. Our simulation results offer a viable route to develop high-efficiency MAGeI₃ perovskite solar cells. Full article

Substoichiometric molybdenum oxide is widely utilized as a hole transport layer (HTL) in polymer solar cells and perovskite solar cells. In this study, the possibility of developing MoOx layers applicable as HTLs with different characteristics by magnetron sputtering from a MoO₃ target and annealing in dry nitrogen or air is explored. The optical transmission and reflection, optical band gap, FTIR and Raman spectra, crystallinity, conductivity, and work function of the films are studied depending on deposition and annealing conditions. The results demonstrate that it is possible to tune the properties of the obtained films with a view toward their application in solar cells. Full article

To meet the demand for highly sensitive temperature sensing in low-temperature environments, a surface plasmon resonance photonic crystal fiber (SPR-PCF) sensor with a central air hole and a dual-layer air-hole arrangement is designed and optimized. In this work, these air-hole features are used for mode-field regulation in a low-temperature sensing structure based on surface plasmon resonance (SPR), together with a polished gold film and an ethanol/chloroform (1:1) temperature-sensitive medium. The finite element method (FEM) was employed to analyze the resonance behavior and thermal response, and key structural parameters, including gold-film thickness, air-hole sizes, and radial positions, were optimized through cumulative parametric scanning. The optimized sensor shows good temperature response from −25 °C to 40 °C, with a maximum sensitivity of 36 nm/°C, a full width at half-maximum (FWHM) of 18.57 nm, and a figure of merit (FOM) of 1.2923. It is promising for cold-chain monitoring, low-temperature storage and transportation, and low-temperature sensing. Full article

When poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is employed as the hole transport layer in visible/near-infrared photodetectors, the extraction and transport of holes are hindered by the accumulation of the PSS insulating phase at the interface. This accumulation results in an increase in contact resistance and creates a potential barrier for hole injection. This study introduces a self-assembled monolayer, (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), to modify PEDOT:PSS, effectively optimizing the interface of the hole transport layer. Such improvements lead to a reduction in recombination losses during charge transfer, a lower dark current, and improved energy level alignment in the device, thereby boosting the performance of visible/near-infrared photodetectors. The fabricated double hole layer photodetector exhibits a low dark current of (1.4 ± 0.6) × 10⁻⁵ A at −1 V bias and a switching ratio of up to 7.62 × 10⁵ at 0 V bias. The device achieves a responsivity of 0.31 A/W and a high specific detection rate of 3.23 × 10¹² Jones at a wavelength of 780 nm, which corresponds to the peak responsivity, showcasing enhanced detection capabilities. In comparison to a reference device based on PEDOT:PSS, the response speed, cutoff frequency, and linear dynamic range of the double hole layer device have been enhanced by 400%, 213%, and 81%, respectively, thereby better aligning with practical application requirements. This research presents a novel approach for the development of high-performance organic visible/near-infrared photodetectors. Full article

In scientific research, the optimization of organic light-emitting diodes (OLEDs) is generally achieved through a lengthy and expensive experimental process as new ideas and configurations are tested on real devices. Electro-optical simulation allows for the rapid evaluation of key performance parameters of device structures, thus reducing manufacturing time and costs. This paper presents an original contribution to the electro-optical modeling and optimization of multilayer OLED devices using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). This optimization explicitly incorporates defect states within the ITO/NPB/Alq₃:C545T/Alq₃/LiF-Al structure. The simulated model is calibrated using experimental data by fitting the trap state distribution. The Pareto front resulting from the multi-objective optimization identifies a set of non-dominated configurations, including an optimal intermediate structure defined by an electron transport layer (ETL) thickness of approximately 42 nm and a hole transport layer (HTL) thickness of approximately 53 nm. This configuration leads to a limited reduction of 1.75–2% in current efficiency (${\eta }_c$) while offering a remarkable improvement of 23–30% in power efficiency (${\eta }_p$) compared to the extreme configurations of the optimal Pareto set. Thus, this solution represents an optimal Pareto trade-off between high current efficiency and improved power efficiency. This paper shows that combining defect modeling and thickness optimization provides a reliable framework for the electro-optical optimization of OLED devices. Future work will extend this approach to spectral and colorimetric analysis. Full article

Layered saline soils containing weakly permeable interlayers exhibit restricted infiltration, surface salt accumulation, and limited deep salt discharge. This study investigated how weakly permeable interlayer thickness, hydraulic-parameter scenario, hole diameter, hole spacing, and irrigation salinity affect soil water redistribution, salt leaching, and profile desalination under vertical-hole treatment. Pilot-scale soil-box experiments were used for model calibration and validation, and HYDRUS-3D simulations were then used for controlled-condition scenario analysis and preliminary layout screening. The weakly permeable interlayer reduced hydraulic connectivity, increased water retention above the interface, and intensified surface salt enrichment, with stronger effects at greater thickness. Vertical holes improved hydraulic continuity and promoted downward percolation and salt leaching, but their effectiveness depended on layout. At a spacing of 30 cm, increasing hole diameter from 5 to 10 cm increased the mean desalination rate from 7.07% to 13.44% in the surface layer and from 4.06% to 18.61% in the deep layer. Irrigation salinity had little effect on water content but increased soil salt accumulation. Under the assumed conceptual cost–performance framework, the 10 cm diameter and 30 cm spacing combination showed the highest composite performance within the tested parameter range. These findings provide a mechanistic basis and preliminary layout-screening reference for vertical-hole treatment in layered saline soils with weakly permeable interlayers. Full article

Lead-free perovskite solar cells have become promising materials in the solar energy field; however, there are some constraints limiting their efficiency, like unfavorable band alignment, high defect densities, and inefficient charge extraction. Cs₃Sb₂I₉ is a lead-free material that has excellent stability, but its experimentally reported efficiencies remain low (<4%). Therefore, Cs₃Sb₂I₉ device performance was investigated using the one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D), where the planar n–i–p structure was analyzed, focusing on its band alignment, transport layers, and key device parameters. The optimized device achieved a power conversion efficiency (PCE) of 13.62%, an open circuit voltage (Voc) of 1.37 V, a short circuit current density (Jsc) of 11.77 mA/cm², and a fill factor (FF) of 84.15% with a 180 nm PCBM electron transport layer, a 150 nm Cu₂O hole transport layer, and a 500 nm absorber thickness. This study advances the development of efficient lead-free perovskite solar cells, promoting sustainable and clean energy. Full article

Organic-type solar cells containing an active layer of block copolymer donor PTB7-Fx (x = 0, 20, and 100), based on benzo [1,2-b:4,5-b’]dithiophene and variably fluorinated thieno [3,4-b]thiophene units, and fullerene acceptor [6,6]phenyl-C₇₁-methylbutyrate, were constructed. The active layer thin film of the solar cells was obtained from a dichlorobenzene solution at an established concentration via spin-coating of the donor–acceptor mixture in the presence of solvent additives such as 3% diiodooctane and 1% triethyl phosphate. Organic photovoltaic elements with normal device architecture were prepared on glass substrates using an indium tin oxide anode, a spin-coated hole transporting layer of poly(ethylene dioxythiophene):polystyrenesulfonate, the aforementioned active layer, followed by an electron transporting layer of zinc oxide nanoparticles, and finally a magnetron sputtered silver (Ag) top-electrode. The optical properties, thin film morphology, and the thickness of the active layers were investigated. Additionally, current density–voltage characteristics and impedance spectra of photovoltaic devices were measured. It was found that PTB7-Fx:PC₇₁BM-based solar cells processed in the presence of two types of solvent additives, diiodooctane and triethyl phosphate, with a sputtered Ag top-electrode display similar absorption and quantum efficiency spectra, as well as comparable current density–voltage characteristics and efficiencies to the same devices fabricated without additives. The diiodooctane solvent additive preferably dissolves the fullerene component and has a positive effect on fill factor enhancement, impedance spectra improvement, and amelioration in charge carrier transport and collection, whereas the triethyl phosphate solvent additive preferentially dissolves the copolymer donor and has a more pronounced impact on the refined morphology of the thin film active layers. Full article

The hole injection layer (HIL) plays a critical role in achieving high efficiency and operational stability in organic light-emitting diodes (OLEDs). As a commonly used HIL, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is limited by its intrinsically low electrical conductivity and mismatched work function alignment with the hole transport layer (HTL), leading to inefficient hole injection and carrier imbalance. In this work, a mild citric acid (CA) treatment is used to simultaneously enhance the conductivity of PEDOT:PSS through the partial removal of insulating PSS and tune its work function for improved energy level alignment at the anode interface. This simultaneous optimization effectively enhances the hole transport capability, successfully matching the electron transport capability to realize highly improved charge carrier balance within the device. Consequently, Ir(ppy)₃-based phosphorescent OLEDs featuring the optimally treated PEDOT:PSS HIL deliver a maximum external quantum efficiency of 20.37%, representing a 21% improvement over devices using pristine PEDOT:PSS, along with a twofold extension in operational lifetime. This strategy demonstrates a simple and controllable approach to interfacial engineering, providing practical guidance for the development of high-performance and stable OLEDs. Full article

Inherently, there exists a significant security hole in sensor networks. The majority of sensors are not high-end Internet of Things (IoT) devices with sufficient computing resources. Connected sensors (physical nodes in real networks) are allocated to logical nodes and managed remotely by a supervisor in a virtual network. Data acquired by sensors are then collected by a data center on which artificial intelligence operates. If an adversary spoofs a logical node (e.g., an account in a transport layer security (TLS) session) of a vulnerable sensor on the network, then it can manipulate data input to artificial intelligence. Artificial intelligence cannot verify the integrity of the data input for learning. It is difficult to stop data poisoning with no countermeasures against session spoofing. To avoid session spoofing, physical and logical nodes must be linked seamlessly. One might think this can be achieved by utilizing Hardware Root-of-Trust (HRoT) based on a Physically Unclonable Function (PUF). However, a PUF is based on an expensive System-on-a-Chip (SoC), which has been specifically designed for high-end devices, like expensive smartphones. Many sensors (low-end and middle-end IoT devices) can hardly be protected with existing PUFs. Since the number of IoT devices with a PUF is insufficient to cover the entirety of IoT devices, an attacker can find a vulnerable IoT device with no PUF to perform session spoofing. This is the problem of numbers. To resolve it, we propose Physical Cyber Authentication (PCA). A Blockchain account (a logical node in a TLS session) is anchored to an integrated circuit (IC) chip inside a sensor, allowing Blockchain to manage sensor networks, which provides necessary data to artificial intelligence, thus forming a Blockchain of sensors. Full article

The discovery of quantum dots (QDs) earned a Nobel Prize and has led to widespread applications in research and technology. In this review, we focus on the use of QDs in solid-state solar cells (QDSCs). We begin with an overview of the basic principles of SCs. Then, we discuss how device architecture has developed over recent decades, setting the stage for the final section on fourth-generation solar cells (Perspective section). We also highlight progress in material development, starting with lead- and cadmium-based QDs and progressing to more recent carbon- and perovskite-based QDs. Additionally, we review materials used for electron-transport layers (ETLs) and hole-transport layers (HTLs). The articles also present recent advances in QDSCs across various QD types. In the final section, we recommend that future research focus on three main areas: QD active-layer materials, material interfaces, and device architecture. These efforts could lead to sustainable QDSCs that potentially surpass the Shockley–Queisser (SQ) limit. Full article