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Organic Solar Cells Efficiency Enhanced by Perylene Mono-Imide Phosphorus Salt Cathode Interfacial Layer
摘要： The composite high-performance electrode is very important for excellent photoelectric device. Interfacial modification is the dominating method to optimize electrode properties. Two easy synthesized perylene-monoimide (PMI) derived organic phosphonium bromide salts were found interestingly valuable when they were applied as cathode interlayers (CIL) in bulk heterojunction (BHJ) organic solar cells (OSCs). Using the PBDB-T:ITIC blend as bulk-hererojunction active layer in inverted device structure, the power conversion efficiency (PCE) was greatly improvement from 9.49% of the referenced device which is without phosphonium CIL to PCE 10.42% with PMI-triphenyl-phosphonium bromide (PMI-TPP) and PCE 9.87% with PMI- trimethoxylphenylphosphonium bromide (PMI-TMOPP) as CIL. Moreover, the two organic phosphonium bromide salts were also investigated by traditional device structure, the PCE was of 4.21% for bare aluminium cathode referenced device contrasted to a moderate increased PCE of 5.18% with PMI-TPP CIL or PCE of 5.05% with PMI-TMOPP CIL. Therefore, organic phosphonium bromide salt PMI-TPP is a promising candidate of CIL material in OSCs.
关键词： cathode interlayer,organophosphorus,energy conversion,electron transfer,solar cell
更新于2025-09-23 15:21:01
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A focus on charge carrier recombination and energy conversion efficiency in nanohybrid photovoltaics
摘要： We investigated the effect of multiwall carbon nanotubes grafted with poly(3-dodecylthiophene) (CNT-graft-PDDT) on the performance of poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester photovoltaic cells. It is demonstrated that the presence of small amounts of these modified CNTs improves the structural organization of the films as evidenced by the grazing incidence wide-angle X-ray scattering studies. The ultraviolet–visible (UV–Vis) spectroscopy revealed that the incorporation of CNT-graft-PDDT changes the absorption intensity and induces a redshift to characteristic peaks. CNT hybrid features have appeared on the surface morphology as verified by atomic force microscopic images. The concentration of additive was optimized at 0.5 wt% to obtain the highest efficiency. Doping with this concentration of CNT-graft-PDDT led to 380% power conversion efficiency improvement by enhancement of short-circuit current density (Jsc) from 5.12 to 11.98 mA/cm2, open-circuit voltage (Voc) from 0.6 to 0.66 V, and fill factor from 0.41 to 0.62 in comparison with a reference cell. The photophysics of hybrid systems were also studied by means of the electrochemical impedance spectroscopy as well as Voc and Jsc dependent on the light intensity.
关键词： Organic photovoltaic cells,Charge carrier recombination,Energy conversion,CNT-graft-PDDT
更新于2025-09-23 15:21:01
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Propulsion effects after laser ablation in water, confined by different geometries
摘要： A Nd:YAG laser with 7-ns pulses and pulse energies up to 10 mJ is used to induce an optical breakdown in the front surface of an aluminum rod, covered by a water layer. The rod is part of a ballistic pendulum. In this way, we study the propulsion effects by means of coupling coefficient and energy-conversion efficiency with respect to different confining geometries, volumes of water applied to the front surface of the rod, and the distance of this surface from the laser-beam focus. Holes with different dimensions are drilled on the target surface and filled with different volumes of water to examine the influence of the confinement by the liquid (a free boundary) and a solid-surface geometry on laser ablation effects. The rod movement and the water ejection after laser ablation are acquired by a high-speed camera with 10k frames per second. The results show that the confinement by cavity substantially increases the propulsion effects by shaping the ejected flow of the liquid; while the cavitation bubble, induced inside the water layer, plays a significant role in propulsion efficiency. From the presented results, it follows that the laser-propelled rod carries below 0.5% of the total mechanical energy after propulsion, while the rest of this energy represents the kinetic energy of the ablated water. As expected, moving the target surface away from the focal position decreases the ablative-propulsion efficiency. When the focus is moved inside the solid target, the decrease occurs due to lower conversion of the pulse energy into the energy of the cavitation bubble. If the focus is moved from the surface outward, the bubble moves towards the liquid–gas interface and it is not able to efficiently eject all the liquid from the target.
关键词： Cavitation bubble,Coupling coefficient,Laser propulsion,Nanosecond laser,Energy-conversion efficiency,Laser ablation
更新于2025-09-23 15:21:01
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Highly Efficient Inorganic-Organic Heterojunction Solar Cells Based on Polymer and CdX (X=Se, Te) Quantum Dots: An Insight from a Theoretical Study
摘要： By using the density functional method, we explore the potentiality of recently synthesized CdX (X=Se, Te)QD/P3HT composites in solar energy conversion devices. Our study reveals that inorganic/organic hybrid CdXQD/P3HT nanocomposites with larger size of CdX QDs exhibit type-II band alignment, suggesting efficient charge separation upon photoexcitation. But for smaller size of QDs, the composites show type-I band alignment which are devoid of charge separation and thus are not suitable for solar cell applications. To remove this obstacle, we focus on chemical modification to polymer P3HT. The substitution of hydrogen at the beta position of each thiophene ring of polymer by electron withdrawing group (CN) results type-II band alignment and yield spatial charge separation even for smaller size of QDs. Finally, we calculated the powerconversion efficiency (PCE) of CdXQD and CN functionalized P3HT nanocomposites. The maximum calculated PCE value of 10.82% is achieved, which makes them immensely competitive with other reported heterojunction solar cells.
关键词： CdX (X=Se, Te)QD/P3HT composites,powerconversion efficiency,solar energy conversion,charge separation,type-II band alignment
更新于2025-09-23 15:21:01
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Hybrid P3HT: PCBM/GaN nanowire/Si cascade heterojunction for photovoltaic application
摘要： Poly (3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) are commonly used for the fabrication of organic photovoltaics (OPV). Efficiency limitations of OPVs could be circumvented by incorporation of inorganic nanostructures into organic blends. Again, integration of organic solar cells with well-developed silicon photovoltaic technology is ultimately desirable. In the present work, GaN nanowires with diameters of 25–50 nm and two lengths (200 and 500 nm) have been grown using molecular beam epitaxy technique. Solar-grade monocrystalline silicon wafers were used as substrates for nanowire synthesis. GaN nanostructures were incorporated into P3HT:PCBM photoactive layer in order to facilitate charge transfer between P3HT:PCBM and Si. Samples with and without nanowires were compared. Addition of nanowires led to the improvement in photovoltaic performance. Open circuit voltage has risen by 72% and short circuit current density by 200%. Series resistance has decreased 50 times, and power conversion efficiency has risen 20.7 times. Additional maxima are found in photocurrent spectrum corresponding to carriers being generated near GaN absorption edge. Moreover, external quantum efficiency peaks near GaN absorption edge, indicating transfer channel via the formation of current P3HT/GaN/Si cascade heterojunction. Mechanism explaining source of abovementioned improvement is proposed.
关键词： Molecular beam epitaxy,Energy conversion,P3HT,Solar cells,PCBM,GaN nanowires
更新于2025-09-23 15:21:01
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Synthesis and Photovoltaic Properties of Boron ?2a??Ketoiminate Dyes Forming A Linear Donora????a??Acceptor Structure
摘要： Organoboron complexes are of interest as chromophores for dye sensitizers owing to their light-harvesting and carrier-transporting properties. In this study, compounds containing boron β-ketoiminate (BKI) as a chromophore were synthesized and used as dye sensitizers in dye-sensitized solar cells. The new dyes were orange or red crystals and showed maximum absorptions in the 410–450 nm wavelength region on titanium dioxide substrates. These electrodes exhibited maximum efficiencies of over 80% in incident photon-to-current conversion efficiency spectra, suggesting that the continuous process of light absorption–excitation–electron injection was effectively performed. Open-circuit photovoltages were relatively high owing to the large dipole moments of the BKI dyes with a linear molecular structure. Thus, a maximum power conversion efficiency of 5.3% was successfully observed. Comparison of BKI dyes with boron β-diketonate dyes revealed certain differences in solution stability, spectral properties, and photovoltaic characteristics.
关键词： chelates,boron,donor-acceptor systems,dyes/pigments,energy conversion
更新于2025-09-23 15:21:01
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Magnetically separable nanocomposites based on ZnO and their applications in photocatalytic processes: A review
摘要： Among the most challenging problems that human beings appear to face are depleting energy sources and increasing environmental pollutions. Heterogeneous photocatalytic processes are the most rewarding technology to generate renewable energy and degrade environmental pollutants. In these processes, semiconductors are used as photocatalysts. ZnO is a widely used photocatalyst, because of its strong oxidation ability, cost effectiveness, non-toxicity, versatility in synthesis, abundance in nature, and ease of crystallization. However, pure ZnO has some drawbacks, due to its wide band gap, poor solar-light utilization, and rapid recombination of the photoinduced charge carriers. Modification of ZnO using different strategies including coupling with narrow band gap semiconductors, noble metal deposition, surface sensitization by organic dyes, and elemental doping can easily address these shortcomings. In addition, separation of photocatalysts from the treated systems limits their broad applications. Incorporation of photocatalysts in magnetic materials will help their recycling using external magnetic field. This combination leads to a new generation of photocatalysts, known as magnetically separable photocatalysts. The present review provides helpful insights into preparation of magnetically separable photocatalysts based on ZnO and their applications for degradations of different pollutants.
关键词： water pollutants,Magnetic photocatalysts,solar-energy conversion,ZnO-based nanocomposites
更新于2025-09-23 15:21:01
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Photoactive Functional Soft Materials (Preparation, Properties, and Applications) || Photomechanical Soft Nanocomposites: Synergies Between Soft Matrix and Energy Conversion Additives
摘要： Photomechanical materials can directly transform light energy into mechanical movements that provide mechanical devices with many advantages, such as non‐contact, remote control, and spatiotemporal resolution. In the past decades, a variety of photoresponsive materials have been developed, and the system based on liquid crystalline polymers (LCPs) is one of the most fascinating ones from the viewpoint of applications as soft photoactuators. However, a simple‐component material system sometimes develops into a bottleneck, such as difficulty in the realization of multiwavelength responsiveness or the flexibility of fabrication. Recently, nanocomposite materials, which combine the superiority of both organic and inorganic materials, have shown more and more potential in photomechanical researches. It is necessary to summarize the recent progresses made with reference to photomechanical soft nanocomposites. In this chapter, we will mainly discuss their design strategy, fabrication, operating principle, and potential applications.
关键词： Energy Conversion,Photomechanical,Soft Nanocomposites,Photoactuators,Liquid Crystalline Polymers
更新于2025-09-23 15:21:01
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[IEEE 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) - New Delhi, India (2019.3.9-2019.3.15)] 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) - Generation of Pulsed Fiber Laser: ns to fs domain
摘要： Thermionic energy converter (TEC) is a heat engine that generates electricity directly using heat as its source of energy and electron as its working fluid. Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuum-based thermionic energy converter development has always been hindered by the space charge problem and the unavailability of materials with low work function. It is only recently that researchers have started to look back into this technology as recent advances in manufacturing technology techniques have made it possible to solve these problems, making TECs a viable option in replacing current energy production systems. The focus of this paper is to review the challenges of producing efficient and practical TECs, along with recent findings and developments in mitigating these challenges. Furthermore, this paper looked into potential applications of TECs, based on recent works and technologies, and found that, with certain improvements, it can be applied in many sectors.
关键词： nanowires,work function,thermionic energy conversion (TEC),space charge,Energy conversion efficiency
更新于2025-09-23 15:19:57
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Evaluation of performance of near-field thermophotovoltaic systems based on entropy analysis
摘要： Near-field radiative heat transfer can significantly improve the output power of thermophotovoltaic (TPV) systems. Therefore, it is crucial to explore how to increase the energy conversion efficiencies of near-field TPV systems. In this study, based on the fluctuation–dissipation theorem with the effective medium theory, we evaluate the performance of a near-field TPV system from the formulation of thermodynamics. It is found that a near-field TPV system consisting of InAs or GaSb cell can achieve higher heat flux or efficiency limit, respectively. Moreover, the TPV system with a hyperbolic metamaterial (HMM) emitter composed of nanowire or nanohole arrays can achieve higher heat flux and efficiency limit compared to that of the bulk reference. This is attributable to the HMMs being able to support hyperbolic modes, and the radiation with the HMM emitter exhibits a favorable entropy content for the energy conversion efficiency. This work provides an approach to determine the efficiency limit and establish a target for efficiency of the near-field TPV system without considering how the system works. The results of this study will facilitate the design and application of the HMM emitter and material of the TPV cell to improve the efficiency of near-field TPV systems.
关键词： Thermophotovoltaic systems,Near-field radiative heat transfer,Energy conversion efficiency,Hyperbolic metamaterial,Entropy analysis
更新于2025-09-23 15:19:57