Search Results (199)

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

We report a novel approach to fabricating high-performance and robust quantum dot light-emitting diodes (QLEDs) utilizing sputtered SnO₂ thin films as the electron transport layer (ETL). While conventional solution-processed ZnMgO NP ETLs face limitations in mass production, the sputtering process offers advantages for uniform and reproducible thin film deposition. Herein, the structural, optical, and electrical properties of SnO₂ thin films were optimized by controlling the Ar/O₂ ratio and substrate heating temperature during sputtering. SnO₂ thin films with O₂ gas improve charge balancing in QLEDs by lowering the conduction band minimum. Furthermore, it was observed that oxygen vacancies in SnO₂ function as exciton quenching sites, which directly impacts the long-term stability of the device. QLEDs fabricated under optimal conditions (Ar/O₂ = 35:5, 200 °C heating) achieved a peak luminance of 99,212 cd/m² and a current efficiency of 21.17 cd/A with excellent device stability. The findings suggest that sputtered SnO₂ ETLs are a highly promising technology for the commercial production of QLEDs. 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

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

Ba_0.6Sr_0.4TiO₃ (BST) thin films were deposited on ITO substrates via rf magnetron sputtering, followed by structural and morphological characterization using XRD and FE-SEM. Metal–insulator–metal (MIM) RRAM devices were fabricated by depositing Al top electrodes, and their electrical properties were examined through I–V measurements. The optimized BST films deposited at 40% oxygen concentration exhibited stable resistive switching, with an operating voltage of 3 V, an on/off ratio of 1, and a leakage current of 10⁻⁸ A. After rapid thermal annealing at 500 °C, the on/off ratio improved to 2 but leakage increased to 10⁻³ A. Incorporating an electron transport layer (ETL) effectively suppressed the leakage current to 10⁻⁵ A while maintaining the on/off ratio at 2. Moreover, a transition from bipolar to unipolar switching was observed at higher oxygen concentration (60%). These results highlight the role of ETLs in reducing leakage and stabilizing switching characteristics, providing guidance for the development of transparent, low-power, and high-reliability BST-based RRAM devices. This study aims to investigate the role of Ba_0.6Sr_0.4TiO₃ (BST) ferroelectric oxide as a functional switching layer in resistive random-access memory (RRAM) and to evaluate how interface engineering using an electron transport layer (ETL) can improve resistive switching stability, leakage suppression, and device reliability. 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

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

Lead-free perovskite solar cells (PSCs) provide a viable alternative to lead-based versions, thereby reducing significant environmental issues related to toxicity. MASnIBr₂ has emerged as a very attractive lead-free perovskite material due to its environmentally friendly characteristics and advantageous optoelectronic capabilities. However, more tuning is required to achieve superior conversion efficiencies (PCEs). This study uses SCAPS-1D simulations to systematically develop and optimize the electron and hole transport layers (ETLs/HTLs) in MASnIBr₂-based perovskite solar cells (PSCs). Iterative simulations are used to carefully examine and optimize critical parameters, including electron affinity, energy bandgap, layer thickness, and doping density. Additionally, the thickness of the MASnIBr₂ absorber layer is optimized to enhance charge extraction and light absorption. Our findings showed a maximum power conversion efficiency of 20.42%, an open-circuit voltage of 1.38 V, a short-circuit current density of 17.91 mA/cm², and a fill factor of 82.75%. This study establishes a basis for future progress in sustainable photovoltaics and offers essential insights into the design of efficient lead-free perovskite solar cells. Full article

Perovskite solar cells (PSCs) have emerged as a promising contender in photovoltaics, owing to their rapidly advancing power conversion efficiencies (PCEs) and compatibility with low-temperature solution processing techniques. Single-junction architectures reveal inherent limitations imposed by the Shockley–Queisser (SQ) limit, motivating adoption of a dual-absorber structure comprising Cs₄CuSb₂Cl₁₂ (CCSC) and Cs₂TiI₆ (CTI)—lead-free perovskite derivatives valued for environmental benignity and intrinsic stability. Comprehensive theoretical screening of 26 electron/hole transport layer (ETL/HTL) candidates identified SrTiO₃ (STO) and CuSCN as optimal charge transport materials, producing an initial simulated PCE of 16.27%. Subsequent theoretical optimization of key parameters—including bulk and interface defect densities, band gap, layer thickness, and electrode materials—culminated in a simulated PCE of 30.86%. Incorporating quantifiable practical constraints, including radiative recombination, resistance, and FTO reflection, revised simulated efficiency to 26.60%, while qualitative analysis of additional factors follows later. Furthermore, comparing multiple algorithms within this theoretical framework demonstrated eXtreme Gradient Boosting (XGBoost) possesses superior predictive capability, identifying CTI defect density as the dominant impact on PCE—thereby underscoring its critical role in analogous architectures and offering optimization guidance for experimental studies. Collectively, this theoretical research delineates a viable pathway toward developing stable, environmentally sustainable PSCs with high properties. Full article

Flexible perovskite solar cells (FPSCs) hold great promise for lightweight and wearable photovoltaics, but improving their efficiency and durability under mechanical stress remains a key challenge. In this work, we fabricate and characterize flexible planar FPSCs on a polyethylene terephthalate (PET). A phenethylammonium iodide (PEAI) surface passivation layer is introduced on the perovskite to form a two-dimensional capping layer, and its impact on device performance and stability is systematically studied. The champion PEAI-passivated flexible device achieves a power conversion efficiency (PCE) of ~16–17%, compared to ~14% for the control device without PEAI. The improvement is primarily due to an increased open-circuit voltage and fill factor, reflecting effective surface defect passivation and improved charge carrier dynamics. Importantly, mechanical bending tests demonstrate robust flexibility: the PEAI-passivated cells retain ~85–90% of their initial efficiency after 700 bending cycles (radius ~5 mm), significantly higher than the ~70% retention of unpassivated cells. This work showcases that integrating a PEAI surface treatment with optimized electron (SnO₂) and hole (spiro-OMeTAD) transport layers (ETL and HTL) can simultaneously enhance the efficiency and mechanical durability of FPSCs. These findings pave the way for more reliable and high-performance flexible solar cells for wearable and portable energy applications. Full article

The fabrication of high-performance organic optoelectronic devices using solution-based techniques, in particular inkjet printing, is both a desirable and challenging goal. Organic light-emitting diodes (OLEDs) are multilayer devices that have demonstrated great potential in display applications, with ongoing efforts aimed at extending their use to the lighting sector. A key objective in this context is the reduction in production costs, for which printing techniques offer a promising pathway. The main obstacle to fully printed OLEDs lies in the difficulty of depositing new layers onto pre-existing ones while maintaining high film quality and avoiding damage to the underlying layers. In a bottom-emitting OLED, the electron transport layer (ETL) is the final organic layer to be deposited, making its printing particularly challenging, a process for which only a few successful examples have been reported. In this work, we report on the optimization of a 2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi)-based ink formulation for ETL printing on an emitting layer composed of 5,10-Bis(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)-2,6-dimethylphenyl)-5,10-dihydroboranthrene (tBuCzDBA). A specific ratio of methanol to diethyl ether was identified as the most suitable for printing the ETL without compromising the integrity of the underlying layer. The printed ETL was successfully integrated into an OLED device, which exhibited a maximum current efficiency of 6.8 cd/A and a peak luminance of about 8700 cd/m². These results represent a significant step toward the development of a fully printed OLED architecture. Full article

The tin dioxide (SnO₂) thin films in this work were prepared by using plasma-enhanced atomic layer deposition (PEALD), and a systematic analysis was conducted to evaluate the influence of post-deposition annealing at various temperatures in a nitrogen–hydrogen mixed atmosphere on their surface morphology, optical behavior, and electrical performance. The SnO₂ films were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall effect measurements. With increasing annealing temperatures, the SnO₂ films exhibited enhanced crystallinity, a higher oxygen vacancy (O_V) peak area ratio, and improved mobility and carrier concentration. These enhancements make the annealed SnO₂ films highly suitable as electron transport layers (ETLs) in perovskite solar cells (PSCs), providing practical guidance for the design of high-performance PSCs. Full article

This study presents a systematic approach to engineering the electron transport layer (ETL) in perovskite solar cells using a spray deposition technique to fabricate sequentially compact and mesoporous titanium dioxide (c-TiO₂, m-TiO₂) films. The spray coating method leads to the development of a distinct reticulated morphology characterized by well-defined wavy-like surface features and significantly increased roughness—at least twice that of spin-coated mesoporous films. The increased interfacial area between the mesoporous TiO₂ and the perovskite layer facilitates more efficient charge transfer, contributing to higher device performance. By optimizing the deposition parameters, particularly the number of spray cycles for the m-TiO₂ layer, we achieve a significant enhancement in device performance, with improvements in power conversion efficiency (PCE), reduced series resistance, and minimized hysteresis. Our results demonstrate that an optimal film thickness promotes better perovskite anchoring, while excessive deposition impedes light transmission and increases sheet resistance. These findings advance the practical fabrication of high-performance perovskite solar cells using simple solution-processing techniques and highlights the potential of scalable spray deposition methods for industrial-scale fabrication. Full article

Tin oxide (SnO₂) is an attractive candidate for the electron transport layer (ETL) in perovskite-based solar cells because of its low temperature process requirement. The ability to form ETL layers at low temperatures opens up opportunities for the use of flexible and low-cost materials suitable for photovoltaic applications. The ETL is necessary for the extraction of electrons and charge separation from the perovskite active layer. Herein, we present a study of the effect of annealing temperature on SnO₂ used as an ETL. The annealing temperature of the SnO₂ has a considerable effect on the morphology, crystallinity, grain size, and surface topography of the SnO₂ layer. The surface properties of the ETL influence the structural properties of the perovskite films. In this study, the annealing temperature of the SnO₂, deposited using spin coating, was changed from 90 °C to 150 °C. The SnO₂ films annealed at 120$°$C resulted in reduced surface defects, improved electron extraction, and produced a significant increase in the grain size of the perovskite active layers. The increase in grain size led to improved efficiency of the PSCs. Devices annealed at 120 °C yielded PSCs with an average efficiency of 15% for a 0.36 cm² active area, while devices treated at 90 °C and 150 °C produced an average efficiency of 12%. The PSCs fabricated at low temperatures provide an effective technique for low-cost manufacturing, especially on flexible and polymer-based substrates. Full article

This study aims to enhance optoelectronic properties of all-inorganic perovskite photodetectors (PDs) by incorporating a bilayer electron transport layer (ETL). The bilayer ETL composed of SnO₂ and ZnO effectively optimizes energy level alignment at the interface, facilitating efficient electron extraction from the CsPbI₂Br perovskite layer while suppressing shunt pathways. Additionally, it enhances interfacial properties by mitigating defects and minimizing dark current leakage, thereby improving overall device performance. As a result, the bilayer ETL-based PDs exhibit broadband photoresponsivity in 300 to 700 nm with a responsivity of 0.45 A W⁻¹ and a specific detectivity of 9 × 10¹³ Jones, outperforming the single-ETL devices. Additionally, they demonstrate stable cyclic photoresponsivity with fast response times (14 μs for turn-on and 32 μs for turn-off). The bilayer ETL also improves long-term reliability and thermal stability, highlighting its potential for high performance, reliability, and practical applications of all-inorganic perovskite PDs. Full article