Search Results (521)

Poly (3,4-ethylenedioxythiophene polystyrene sulfonate) (PEDOT:PSS) is a solution-processable hole transport layer known for its high work function and excellent hole mobility. The incorporation of graphene serves as an effective strategy to augment the hole-transport properties of PEDOT:PSS. In this study, the electronic structure of graphene-doped PEDOT:PSS (G-PEDOT:PSS) was investigated using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). It was found that the work function of PEDOT:PSS increases with graphene doping concentration, rising from 4.86 eV for undoped PEDOT:PSS to 5.03 eV for PEDOT:PSS incorporating 10 wt% graphene. The impact of this modification on the energy-level alignment with zinc phthalocyanine (ZnPc), which is a prototypical p-type organic semiconductor, was examined through in situ XPS and UPS analyses. Despite the increased work function, the hole injection barriers for both PEDOT:PSS and G-PEDOT:PSS to ZnPc were determined to be identical at 0.26 eV. This lack of change in the barrier is explicitly attributed to Fermi-level pinning, where the integer charge transfer level of ZnPc is pinned to the Fermi level of the substrate, preventing a further reduction in the energy offset. That said, for other p-type organic semiconductors with higher ionization energies, the use of G-PEDOT:PSS could potentially enable more efficient hole injection. Full article

The increasing impact of global warming is predominantly driven by the extensive use of fossil fuels, which release significant amounts of greenhouse gases into the atmosphere. This has led to a critical need for alternative, sustainable energy sources that can mitigate environmental impacts. Photovoltaic technology has emerged as a promising solution by harnessing renewable energy from the sun, providing a clean and inexhaustible power source. Perovskite solar cells (PSCs) are a class of hybrid organic–inorganic solar cells that have recently attracted significant scientific attention due to their low cost, relatively high efficiency, low–temperature processing routes, and longer carrier lifetimes. These characteristics make them a viable alternative to traditional fossil fuels, reducing the carbon footprint and contributing to the fight against global warming. In this study, the SCAPS–1D numerical simulator was used in the computational analysis of a PSC device with the configuration FTO/ETL/BaZr(S_0.6Se_0.4)₃/HTL/Ir. Different hole transport layer (HTL) and electron transport layer (ETL) material were proposed and tested. The HTL materials included copper (I) oxide (Cu₂O), 2,2′,7,7′–Tetrakis(N,N–di–p–methoxyphenylamine)9,9′–spirobifluorene (spiro–OMETAD), and poly(3–hexylthiophene) (P₃HT), while the ETLs included cadmium suphide (CdS), zinc oxide (ZnO), and [6,6]–phenyl–C₆₁–butyric acid methyl ester (PCBM). Finally, BaZr(S_0.6Se_0.4)₃ was proposed as an absorber, and a fluorine–doped tin oxide glass substrate (FTO) was proposed as an anode. The metal back contact used was iridium. Photovoltaic parameters such as short circuit density (I_sc), open circuit voltage (V_oc), fill factor (FF), and power conversion efficiency (PCE) were used to evaluate the performance of the device. The initial simulated primary device with the configuration FTO/CdS/BaZr(S_0.6Se_0.4)₃/spiro–OMETAD/Ir gave a PCE of 5.75%. Upon testing different HTL materials, the best HTL was found to be Cu₂O, and the PCE improved to 9.91%. Thereafter, different ETLs were also inserted and tested, and the best ETL was established to be ZnO, with a PCE of 10.10%. Ultimately an optimized device with a configuration of FTO/ZnO/BaZr(S_0.6Se_0.4)₃/Cu₂O/Ir was achieved. The other photovoltaic parameters for the optimized device were as follows: FF = 31.93%, J_sc = 14.51 mA cm⁻², and V_oc = 2.18 V. The results of this study will promote the use of environmentally benign BaZr(S_0.6Se_0.4)₃–based absorber materials in PSCs for improved performance and commercialization. Full article

Metal halide perovskite (MHP)-based heterojunctions have become a forefront area in the research of optoelectronic functional materials due to their unique layered crystal structure, tunable band gaps, and exceptional optoelectronic properties. Recent studies have demonstrated that interface charge transfer is a crucial factor in determining the optoelectronic performance of the heterojunction devices. By constructing heterojunctions between MHPs and two-dimensional (2D) materials such as graphene, MoS₂, and WS₂, efficient electron–hole separation and transport can be achieved, significantly extending carrier lifetimes and suppressing non-radiative recombination. This results in enhanced response speed and energy conversion efficiency in photodetectors, photovoltaic devices, and light-emitting devices (LEDs). In these heterojunctions, the thickness of the MHP layer, interface defect density, and band alignment significantly influence carrier dynamics. Furthermore, techniques such as interface engineering, molecular passivation, and band engineering can effectively optimize charge separation efficiency and improve device stability. The integration of multilayer heterojunctions and flexible designs also presents new opportunities for expanding the functionality of high-performance optoelectronic devices. In this review, we systematically summarize the charge transfer mechanisms in MHP-based heterojunctions and highlight recent advances in their optoelectronic applications. Particular emphasis is placed on the influence of interfacial coupling on carrier generation, transport, and recombination dynamics. Furthermore, the ultrafast dynamic behaviors and band-engineering strategies in representative heterojunctions are elaborated, together with key factors and approaches for enhancing charge transfer efficiency. Finally, the potential of MHP heterojunctions for high-performance optoelectronic devices and emerging photonic systems is discussed. This review aims to provide a comprehensive theoretical and experimental reference for future research and to offer new insights into the rational design and application of flexible optoelectronics, photovoltaics, light-emitting devices, and quantum photonic technologies. Full article

This study investigates the feasibility of adding gold nanoparticles (Au-NPs) to vanadium oxide (V₂O_x) serving the hole transport layer (HTL) material oin polymer solar cells to enhance cell performance. The first part of this study used Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a baseline and optimized the parameters of this HTL material. Then, the V₂O_x was substituted as the HTL material, and its parameters were optimized again. The second part involved incorporating an aqueous solution of gold nanoparticles (Au-NPs) with an average particle size of approximately 80 nm into V₂O_x. Due to the excitation of localized surface plasmon resonance (LSPR) by Au-NPs, the addition of Au-NPs to the V₂O_x layer can enhance the absorption efficiency of the P3HT:PCBM blended film. Therefore, compared with V₂O_x alone, the solar cells with Au-NPs incorporated into the V₂O₅ hole transport layer demonstrate improved power conversion efficiency (PCE). Full article

Cadmium-free buffer layers are pivotal for the sustainable development of thin-film photovoltaics. This work numerically investigates SnS₂ as a high-performance, environmentally benign alternative to CdS for antimony selenosulfide (Sb₂(S,Se)₃) solar cells using AFORS-HET software. The SnS₂/Sb₂(S,Se)₃ heterojunction exhibits a significantly lower conduction band offset (CBO ≈ 0.23 eV) than its CdS counterpart (CBO ≈ 0.49 eV), which is identified as the primary factor for suppressed interface recombination and enhanced electron injection efficiency. A comprehensive optimization strategy is presented: tuning the S content in Sb₂(S,Se)₃ to 40% optimizes the trade-off between band gap widening and hole transport barrier at the ETL/absorber interface; adjusting the absorber thickness to 340 nm balances light absorption and carrier collection efficiency; and elevating the SnS₂ carrier concentration to 10²¹ cm⁻³ strengthens the built-in potential and induces a beneficial hole-blocking “spike” at the front contact. The synergistically optimized device achieves a power conversion efficiency (PCE) of 10.39%, a substantial improvement over the 7.56% efficiency of the CdS-based reference cell in our simulation framework. Full article

Against the backdrop of global water scarcity, utilizing sediment-laden river water for agricultural irrigation is a critical strategy for ensuring food security. However, the associated water and nitrogen transport processes are influenced by the coupled effects of multiple factors, and the governing mechanisms are not yet fully understood. To investigate the coupled effects of muddy water sediment concentration (ρ), physical clay content (d_0.01), applied nitrogen concentration (N), and pressure head (H) on infiltration characteristics during film hole irrigation, this study conducted an indoor soil-box experiment using an orthogonal design to analyze soil water and nitrogen transport dynamics. Results indicated that sediment properties were the dominant factors governing infiltration, with their relative influence on cumulative infiltration following the order ρ > d_0.01 > H > N. ρ and d_0.01 strongly inhibited infiltration; for instance, an increase in ρ from 3% to 9% reduced the initial infiltration rate by as much as 49.3%. Conversely, H and N exhibited a slight promoting effect. High muddy water sediment concentration and physical clay content significantly restricted water and nitrogen transport, causing substantial amounts of ammonium nitrogen (NH₄⁺-N) to be retained within the surface soil layer adjacent to the irrigation hole. Paradoxically, the same factors that reduced infiltration (ρ and d_0.01) led to a significant increase in the average change in volumetric water content (Δθ) within the wetted soil volume. Based on these findings, multivariate power function models were developed to predict key parameters. The models demonstrated high predictive accuracy, with coefficients of determination (R²) of 0.9715 for cumulative infiltration, 0.94 for wetting front migration, and 0.9758 for Δθ, and validation errors were within acceptable limits. In conclusion, the film hole irrigation process is predominantly governed by physical clogging from sediment particles, a mechanism that decisively controls the spatial distribution of water and nitrogen. Furthermore, the slight enhancement of infiltration by nitrogen fertilizer suggests a potential physicochemical mechanism, possibly involving ion-induced flocculation of clay particles. The models developed in this study provide a quantitative basis for precision fertigation management in China’s Yellow River irrigation district and other regions with similar conditions. Full article

We introduce a fully solution-processed interlayer strategy for n–p CdS/PbS thin film solar cells that combines a sol–gel ZnO compact coating with an electrospun ZnO nanofiber network. The synthesis and characterization of ZnO, CdS, and PbS thin films, complemented by electrospun ZnO nanofibers, are aimed at low-cost photovoltaic applications. Sol–gel ZnO films exhibited a hexagonal wurtzite structure with a bandgap (Eg) of approximately 3.28 eV, functioning effectively as electron transport and hole-blocking layers. CdS films prepared by chemical bath deposition (CBD) showed mixed cubic and hexagonal phases with an Eg of about 2.44 eV. PbS films deposited at low temperature displayed a cubic galena structure with a bandgap of approximately 0.40 eV. Scanning Electron Microscopy revealed uniform ZnO and CdS surface coatings and a conformal 1D ZnO network with nanofibers measuring about 50 nm in diameter (ranging from 49.9 to 53.4 nm), which enhances interfacial contact coverage. PbS films exhibited dense grains ranging from 50 to 150 nm, and EDS confirmed the expected stoichiometries. Electrical characterization indicated low carrier densities and high resistivities consistent with low-temperature processing, while mobilities remained within reported ranges. The incorporation of ZnO layers and nanofibers significantly improved device performance, particularly at the CdS/PbS heterojunction. The device achieved a V_oc of 0.26 V, an J_sc of 3.242 mA/cm², and an efficiency of 0.187%. These improvements are attributed to enhanced electron transport selectivity and reduced interfacial recombination provided by the percolated 1D ZnO network, along with effective hole blocking by the compact film and increased surface area. Fill-factor limitations are linked to series resistance losses, suggesting potential improvements through fiber densification, sintering, and control of the compact layer thickness. This work is a proof-of-concept of a fully solution-processed and low-temperature CdS/PbS architecture. Efficiencies remain modest due to low carrier concentrations typical of low-temperature CBD films and the deliberate omission of high-temperature annealing/ligand exchange. Overall, this non-vacuum, low-temperature coating method establishes electrospun ZnO as a tunable functional interlayer for CdS/PbS devices and offers a practical pathway to elevate power output in scalable productions. These findings highlight the potential of nanostructured intermediate layers to optimize charge separation and transport in low-cost PbS/CdS/ZnO solar cell architectures. Full article

Molybdenum oxide (MoO_X) has been widely utilized as a hole transport layer (HTL) in crystalline silicon (c-Si) solar cells, owing to characteristics such as a wide bandgap and high work function. However, the relatively low conductivity of MoO_X films and their poor contact performance at the MoO_X-based hole-selective contact severely degrade device performance, particularly because they limit the fill factor (FF). Oxygen vacancies are of paramount importance in governing the conductivity of MoO_X films. In this work, MoO_X films were modified through ultraviolet irradiation (UV-MoO_X), resulting in MoO_X films with tunable oxygen vacancies. Compared to untreated MoO_X films, UV-MoO_X films contain a higher density of oxygen vacancies, leading to an enhancement in conductivity (2.124 × 10⁻³ S/m). In addition, the UV-MoO_X rear contact exhibits excellent contact performance, with a contact resistance of 20.61 mΩ·cm², which is significantly lower than that of the untreated device. Consequently, the application of UV-MoO_X enables outstanding hole selectivity. The power conversion efficiency (PCE) of the solar cell with an n-Si/i-a-Si:H/UV-MoO_X/Ag rear contact reaches 24.15%, with an excellent FF of 84.82%. Full article

In this work the authors analyze a CdS/SnSe solar cell using a SnTe as a hole transport layer. We analyzed the impact of the recombination mechanisms namely radiative, and Shockley–Read–Hall in the bulk and at the interfaces using SCAPS-1D software and the impact of SnSe and CdS layer thickness. Additionally, the effect of concentration of acceptors and bulk defects in SnTe and SnSe on the performance were studied. The conditions that optimize device performance are presented. The results of the present study suggest that using a SnTe hole transport layer can result in an efficiency promotion from 0.7% to 24.48%. Full article

In response to the rising global energy dilemma and associated environmental concerns, research into creating less hazardous solar technology has exploded. Due to their cost-effective fabrication process and exceptional optoelectronic properties, perovskite-based solar cells have emerged as promising candidates. However, their commercialization faces obstacles, including lead contamination, interface recombination, and instability. This study examines CaV_0.5Fe_0.5O₃ (CVFO) as an alternative to lead-based perovskites, highlighting its improved stability and high efficiency through a series of simulation and modeling results. A record power conversion efficiency (PCE) of 23.28% was achieved (V_oc = 1.38 V, J_sc = 19.8 mA/cm², FF = 85.2%) using a 550 nm thick CaV_0.5Fe_0.5O₃ as an absorber. This was accomplished by optimizing the electron transport layer (ETL: TiO₂, 40 nm, 10²⁰ cm⁻³ doping) and the hole transport layer (HTL: Cu₂O, 50 nm, 10²⁰ cm⁻³ doping). Subsequently, it was established that defects at the ETL/perovskite interface significantly diminish performance relative to defects on the HTL side, and thermal stability assessments verified proper operation up to 350 K. To maintain efficiency, it is necessary to reduce series resistance (R_s < 1 Ω·cm²) and increase shunt resistance (R_sh > 10⁴ Ω·cm²). The findings indicate that CaV_0.5Fe_0.5O₃ serves as a feasible alternative to perovskites and has the potential to enhance the performance of scalable solar cells. Full article

In this study, p-type NiO_x and Cu-doped NiO_x nanoparticles (NPs) were synthesized by a simple chemical precipitation method and used as hole transport layers (HTLs) for inverted perovskite solar cells (PSCs). The microstructural property, surface morphology, elemental composition, optical property, charge recombination, and surface topography of the NiO_x and Cu-NiO_x HTLs were comprehensively characterized. The results showed that the NiO_x and Cu-NiO_x NPs were uniformly coated on the substrates without pinholes or voids. Cu incorporation into NiO_x did not change its crystalline nature and considerably improved its electrical conductivity. The Cu-NiO_x HTLs exhibited superior photoluminescence quenching and the least lifetime decay, which indicated that Cu-NiO_x exhibited higher charge transport than NiO_x HTLs. The fabricated PSC performances were further analyzed using current density–voltage characteristics, external quantum efficiency, and electrochemical impedance spectroscopy. The PSCs with PEDOT:PSS, NiO_x, and 2% Cu-NiO_x HTLs exhibited power conversion efficiencies of 11.93%, 13.72%, and 15.54%, respectively. The 2% Cu-NiO_x HTL-based device showed the best performance compared with the PEDOT:PSS- and NiO_x-based devices. Academic Editors: Chunyang Zhang, Dou Zhang Full article

Cu₂O solar cells are regarded as a promising emerging inorganic photovoltaic technology due to their power conversion efficiency (PCE) potential and material sustainability. While previous studies primarily focused on the band offset between n-type buffer layers and Cu₂O optical absorption, this work systematically investigated an ETL/buffer/p-Cu₂O/HTL heterojunction structure using SCAPS-1D simulations. Key design parameters, including bandgap (Eg) and electron affinity (χ) matching across layers, were optimized to minimize carrier transport barriers. Furthermore, the doping concentration and thickness of each functional layer (ETL: transparent conductive oxide; HTL: hole transport layer) were tailored to balance electron conductivity, parasitic absorption, and Auger recombination. Through this approach, a maximum PCE of 14.12% was achieved (V_oc = 1.51V, J_sc = 10.52 mA/cm², FF = 88.9%). The study also identified candidate materials for ETL (e.g., GaN, ZnO:Mg) and HTL (e.g., ZnTe, NiO_x), along with optimal thicknesses and doping ranges for the Cu₂O absorber. These findings provide critical guidance for advancing high-performance Cu₂O solar cells. Full article

In this study, structural optimization and trap effect analysis of a 4H-SiC–based p–i–n betavoltaic (BV) cell were performed using Silvaco ATLAS TCAD (version 5.30.0.R) simulations combined with an electron-beam (e-beam) irradiation model. First, the optimum device structure was derived by varying the thickness of the intrinsic layer (i-layer), the thickness of the p-layer, and the doping concentration of the i-layer. Under 17 keV e-beam irradiation, the electron–hole pairs generated in the i-layer were effectively separated and transported by the internal electric field, thereby contributing to the short-circuit current density (J_SC), open-circuit voltage (V_OC), and maximum output power density (P_{out_max}). Subsequently, to investigate the effects of traps, donor- and acceptor-like traps were introduced either individually or simultaneously, and their densities were varied to evaluate the changes in device performance. The simulation results revealed that traps degraded the performance through charge capture and recombination, with acceptor-like traps exhibiting the most pronounced impact. In particular, acceptor-like traps in the i-layer significantly reduced V_OC from 2.47 V to 2.07 V and P_{out_max} from 3.08 μW/cm² to 2.28 μW/cm², demonstrating that the i-layer is the most sensitive region to performance degradation. These findings indicate that effective control of trap states within the i-layer is a critical factor for realizing high-efficiency and high-reliability SiC-based betavoltaic cells. Full article

Due to its unique electrical and optical properties, as well as the tunable band structure based on thickness, 2D phosphorene recently emerged as a research hotspot and holds significant potential for applications across various fields. In this study, due to the special band structure and excellent electron transport performance of phosphorene, it formed a series structure with SnO₂ as the electron transport layer of perovskite solar cells. Consequently, the photocurrent density was enhanced by approximately 20%, and the energy conversion efficiency was effectively elevated from 16.38% for pure SnO₂ to 18.03% for the SnO₂/phosphorene composite. Electrochemical measurements and spectral analyses revealed that the incorporation of phosphorene augmented electron mobility within the absorption layer, reduced the electron–hole recombination rate, and decreased the cell’s series resistance, thereby leading to improved efficiency of the perovskite solar cell. This research not only introduces a novel approach to enhancing solar cell efficiency but also paves a new pathway for the application of phosphorene. Full article

NiO-based hole-transport layers are crucial for high-efficiency perovskite solar cells. An industrial deposition method of NiO films is magnetron sputtering using ceramic targets. NiO targets doped with Li contents at 1%, 3%, and 5% were designed, and the doping contents and sintering temperatures were investigated. All the targets have a face-centered cubic phase, dense microstructure, and an average size of a few microns. The NLO targets sintered at an optimal temperature of 1400 °C exhibited high relative density (>98%) and low resistivity (<6 Ω∙cm). These results pave the way for depositing NiO-based hole-transport layer by magnetron sputtering. Full article