- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Thinning ferroelectric films for high-efficiency photovoltaics based on the Schottky barrier effect
摘要： Achieving high power conversion efficiencies (PCEs) in ferroelectric photovoltaics (PVs) is a longstanding challenge. Although recently ferroelectric thick films, composite films, and bulk crystals have all been demonstrated to exhibit PCEs >1%, these systems still suffer from severe recombination because of the fundamentally low conductivities of ferroelectrics. Further improvement of PCEs may therefore rely on thickness reduction if the reduced recombination could overcompensate for the loss in light absorption. Here, a PCE of up to 2.49% (under 365-nm ultraviolet illumination) was demonstrated in a 12-nm Pb(Zr0.2Ti0.8)O3 (PZT) ultrathin film. The strategy to realize such a high PCE consists of reducing the film thickness to be comparable with the depletion width, which can simultaneously suppress recombination and lower the series resistance. The basis of our strategy lies in the fact that the PV effect originates from the interfacial Schottky barriers, which is revealed by measuring and modeling the thickness-dependent PV characteristics. In addition, the Schottky barrier parameters (particularly the depletion width) are evaluated by investigating the thickness-dependent ferroelectric, dielectric and conduction properties. Our study therefore provides an effective strategy to obtain high-efficiency ferroelectric PVs and demonstrates the great potential of ferroelectrics for use in ultrathin-film PV devices.
关键词： power conversion efficiency,Schottky barrier effect,ferroelectric photovoltaics,PZT ultrathin film,depletion width
更新于2025-11-14 17:28:48
-
Charge transport and electron recombination suppression in dye-sensitized solar cells using graphene quantum dots
摘要： In this study, TiO2 photoelectrodes were sensitized in different concentration of Graphene Quantum Dots (GQDs) solution to enhance photovoltaic performance and charge transport of DSSC. The performance of pristine TiO2 and TiO2-GQDs photoelectrodes were compared to investigate the effect of GQDs incorporation in DSSC. It was found GQDs increased light absorption of TiO2 photoelectrode at visible spectrum in the range of λ = 375 nm to λ = 600 nm, resulting highest current–density, Jsc and photon-to-current conversion efficiency, ?c. Solar cell sensitized in 7.5 mg/ml concentration of GQDs known as (PG 7.5) cell shown the highest reading by 15.49 mA cm?2 and 6.97%, which indicated an improvement by 28.07% and 70.83% for Jsc and ? compare to pristine TiO2 DSSC at 12.10 mA cm?2 and 4.08%. Photoluminescence property own by GQDs may enhance photon emission to visible region when uv-ray excited on solar cell. Thus, generate more electron-hole pairs in the photoelectrode and enhance the photovoltaic parameters of DSSC. PG 7.5 cell also exhibited lowest series resistance (Rs) of 36.60 Ω, highest charge transfer resistance (Rct2) of 41.98 Ω and electron lifetime of 6.33 ms among other DSSC. These possibly due to suppression of recombination between TiO2/dye/electrolyte interfaces. Hence, resulting highest charge collection efficiency (CCE) of 53.42%. The EIS analysis confirmed the PV performance of the best cell of PG 7.5 since the same cell also generated the best photon-current conversion efficiency (PCE). This study revealed GQDs can enhanced photovoltaic parameter and charge collection efficiency of DSSC.
关键词： Charge collection efficiency,GQDs-DSSC,TiO2-GQDs,Charge transport
更新于2025-11-14 17:04:02
-
Construction of a high-performance photocatalytic fuel cell (PFC) based on plasmonic silver modified Cr-BiOCl nanosheets for simultaneous electricity production and pollutant removal
摘要： The development of high-performance photocatalytic fuel cell (PFC) is seriously hampered by the poor light utilization rate and low charge carriers transfer efficiency. Herein, we have experimentally obtained the plasmonic Ag modified Cr-BiOCl (Cr-BOC/Ag) with high visible light photocatalytic activity and provided direct evidence for the substantially enhanced catalytic activity in metal-semiconductor photocatalysts. The experimental results revealed that the Cr doping and Ag modification could not only extend the photo absorption of BiOCl from the UV to the visible light region but also greatly increase the generation and transfer rate of charge carriers because of its narrowed band gap and the localized surface plasmon resonance (LSPR) effect of metallic Ag. Under visible light irradiation, the Cr-BOC/Ag showed the remarked enhancement on PFC performance when the optimum contents of Cr doping and Ag loading was 14.4% and 4%, respectively. The trapping experiments and multiple characterizations demonstrated that the advantageous combination of Cr doping effect and SPR effect induced by the Ag nanoparticles is responsible for the high generation rate of oxidative species and effective charge carriers transfer. By using RhB as fuel, approximately 75.1% color removal efficiency and 8.38% Coulombic efficiency were obtained under visible light irradiation for 240 min, which are higher than that of MO and TC. And, the Jsc and Voc of Cr-BOC/Ag photoanode were measured to be 0.0073 mA/cm2 and 0.543 V.
关键词： photocatalytic degradation,SPR,BiOCl,coulombic efficiency,visible light,fuel cell
更新于2025-11-14 17:03:37
-
Bulk luminescent solar concentrators based on organic-inorganic CH3NH3PbBr3 perovskite fluorophores
摘要： In this paper, we report characterization and performance results of lead bromide perovskite luminescent solar concentrator. CH3NH3PbBr3 fluorophores are synthesized by sonication method and examined by their X-ray diffraction pattern and scanning electron microscopy. Synthesized perovskite shows excitonic absorption at 524 nm and PL emission peak located at 532 nm with a Stokes shift around 8 nm. Micron-sized fluorophores are dissolved in prepared solutions and uniformly embedded in PMMA host with 0.006–0.120%wt concentration. Then, Fabricated devices are cut into 50 × 30 × 5 mm cuboid shapes and placed in a mirror surrounded configuration with an attached photovoltaic cell. Fabricated device is put under standard AM1.5 illumination and the output spectrum from the concentrator is acquired. Re-absorption in the samples is also measured by variable optical path method, showing red-shifts up to 13 nm in the output spectrum. Spatially resolved photo-luminescence maps and optical efficiencies are also presented for each sample. Plus, a Monte-Carlo ray tracing algorithm is developed to assist better understanding the experimental results. Stability of fabricated samples are evaluated under high intensity UV illumination, reporting efficiency reduction around 15% after 24 h. Finally, Comparing current-voltage characterization of the attached photovoltaic cell reveals optimized efficiency enhancement in the 0.04%wt sample above 65%.
关键词： Perovskites,Monte-Carlo simulation,Re-absorption,Luminescent solar concentrators,Photovoltaic conversion efficiency,Solar cells
更新于2025-11-14 15:30:11
-
Au@Ag@Ag2S heterogeneous plasmonic nanorods for enhanced dye-sensitized solar cell performance
摘要： Au@Ag@Ag2S heterogeneous nanorods (NRs) with two strong plasmonic absorptive bands were developed for boosting the performance of dye-sensitized solar cells, and the remarkably enhanced plasmonic devices were achieved. By doping different concentrations of the Au@Ag@Ag2S NRs within the TiO2 photoanode layers, various enhanced effects of the plasmonic devices were obtained. With the incorporation of the typical Au@Ag@Ag2S NRs (their aspect ratios: 2.7) into the TiO2 photoanodes, the top efficiency of 6.51% of the fabricated plasmonic photovoltaic devices at their doped concentrations of the 2.31% was observed, exhibiting dramatic 40% enhancement than that of the conventional dye-sensitized solar cells (bare device: 4.65%). Benefiting from effective surface plasmon effects of the Au@Ag@Ag2S NRs, the light-harvesting abilities of photoanodes and dyes in devices are dramatically enhanced, which in return boost the whole performance of photovoltaic devices significantly.
关键词： Dye-sensitized solar cell,Nanorod,Power conversion efficiency,Plasmonic effect
更新于2025-11-14 15:27:09
-
Enabling low voltage losses and high photocurrent in fullerene-free organic photovoltaics
摘要： Despite significant development recently, improving the power conversion efficiency of organic photovoltaics (OPVs) is still an ongoing challenge to overcome. One of the prerequisites to achieving this goal is to enable efficient charge separation and small voltage losses at the same time. In this work, a facile synthetic strategy is reported, where optoelectronic properties are delicately tuned by the introduction of electron-deficient-core-based fused structure into non-fullerene acceptors. Both devices exhibited a low voltage loss of 0.57 V and high short-circuit current density of 22.0 mA cm?2, resulting in high power conversion efficiencies of over 13.4%. These unconventional electron-deficient-core-based non-fullerene acceptors with near-infrared absorption lead to low non-radiative recombination losses in the resulting organic photovoltaics, contributing to a certified high power conversion efficiency of 12.6%.
关键词： non-fullerene acceptors,power conversion efficiency,voltage losses,charge separation,organic photovoltaics
更新于2025-11-14 15:18:02
-
Soft tissue cutting efficiency by 980?nm laser with carbon-, erbium-, and titanium-doped optothermal fiber converters
摘要： Objectives: The use of near-IR diode lasers for contact soft tissue surgery is attended by a risk of severe thermal damage of surrounding tissues due to the low cutting efficiency of these lasers. To increase the cutting efficiency tips of a near-IR lasers in contact surgery special (converters) which transform laser light to heat are used. The present in vivo study evaluated temperature dynamics and soft tissue cutting efficiency of 980 nm diode laser equipped with standard carbon- and novel erbium- and titanium-doped converters. Materials and Methods: For in vitro treatment on soft tissue (chicken thigh), 980 nm diode laser was used. The radiation was delivered to the tissue by a quartz fiber with a core diameter of 400 ± 5 mm. The carbon-, erbium-, or titanium-doped converters were mounted at the fiber distal end. The converters temperature was measured by IR-sensor integrated into the laser radiation delivery system. The temperature dynamics of each converter during soft tissue treatment was evaluated. The converter was in contact with the soft tissue surface and moved across the surface of soft tissue with a speed of 1, 3, or 6 mm/s. The average power of laser radiation was 0.3, 1.0, or 4.0 W. The collateral thermal damage of treated soft tissues was evaluated using NTBC stain. The width and depth of coagulation and ablation zones of laser wounds was determined. The soft tissue cutting efficiency with different converters was calculated. Results: The cutting efficiency, collateral damage, and converter temperature in contact with soft tissue change depending on the type of converter, the power of laser radiation and the converter movement speed along the temperature tissue (1,980 ± 154 °C), at which a tissue cut takes place, was fixed for Ti-doped converter for laser power of 4.0 W and movement speed of 1 mm/s. Minimal converter temperature (540 ± 30 °C), at which a tissue cut takes place, was fixed for Ti-doped converter for laser power of 1.0 W and movement speed of 6 mm/s. Maximal depth of coagulation (0.72 ± 0.10 mm) was fixed for Ti-doped converter for laser power of 4.0 W and movement speed of 1 mm/s. Minimal depth of coagulation (0.11 ± 0.02 mm) was fixed for C-doped converter for laser power of 0.3 W and movement speed of 3 mm/s. Maximal cutting efficiency (0.57 mm3/W) was fixed for Er-doped converter for laser power of 1.0 W and movement speed of 1 mm/s. Minimal cutting efficiency (0.02 mm3/W) was fixed for C-doped converter for laser power of 4.0 W and movement speed of 6 mm/s. Conclusion: All three studied types of converters can be used for contact surgery of soft tissues by 980 nm diode laser. Er-doped and Ti-doped converters are more resistant to laser heating then C-doped converter, they dissect soft tissue more effectively. This will also expand the potential of everyday routine clinical procedures, making them safer, faster, and easier. These converters can be used in general surgery, plastic surgery, dermatology, angioplasty, dentistry, neurosurgery, etc. Lasers Surg. Med. 9999:1–16, 2018. ? 2018 Wiley Periodicals, Inc.
关键词： soft tissue,coagulation,surgery,efficiency,IR-sensor,diode laser,cutting,converter,fiber
更新于2025-10-24 16:41:07
-
Effect of Thionation on the Performance of PNDIT2-Based Polymer Solar Cells
摘要： All-polymer solar cells have gained traction in recent years with solar cell performance of over 11% power conversion efficiency (PCE) recently demonstrated. The n-type polymer PNDIT2, also known as N2200 or P(NDI2OD-T2), has been extensively used for both photovoltaic as well as field-effect transistor applications. When paired with donor materials that have appropriately aligned energy-levels, PNDIT2 has exhibited device efficiencies over 10% PCE, and organic field effect transistors fabricated with PNDIT2 exhibit mobilities over 1 cm2/Vs. Thionation of the NDI moiety, which is the substitution of imide oxygen with sulfur atoms, has been shown to improve the field-effect transistor performance of NDI-based small molecules. Applying this strategy to PNDIT2, we explored the effect that thionation, in a 2S-trans configuration, has on the performance of all-polymer solar cells fabricated with the donor polymer PTB7-Th. Solar cells were fabricated with the original polymer, PNDIT2, as a reference, and an optimized efficiency of 4.85% was achieved. As samples with 100% conversion to 2S-trans configuration could not be produced due to synthetic limitations, batches with increasing ratios of 1S to 2S-trans thionation (15:85, 7:93, and 5:95) were studied. Devices with thionated PNDIT2 exhibited a systematic lowering of photovoltaic parameters with increasing thionation, resulting in device efficiencies of just 0.84%, 0.62%, and 0.42% PCE. The lower performance of the thionated blends is attributed to poor π-π stacking order in the thionated PNDIT2 phase, resulting in lower electron mobilities and finer phase separation. Evidence in support of this conclusion is provided by grazing incidence wide-angle X-ray scattering, transmission electron microscopy, photoluminescence quenching, transient photocurrent analysis, and SCLC measurements.
关键词： π-π stacking,PNDIT2,Thionation,All-polymer solar cells,Power conversion efficiency
更新于2025-10-22 19:40:53
-
Power Efficiency Figure of Merit for Image Sensors
摘要： A new figure of merit (FoM) is developed with a theory, which enables the comparison of power efficiency of different image sensors based only on the pixel array size, frame rate, and total power consumption. The mathematical foundation of the FoM is provided, enabling the application of FoM to a generic image sensor supporting various read-out configurations. The model assumes a nonlinear relationship between the power consumption and operating frequency of building blocks, and the nonlinear factor is numerically derived based on the analytical modeling of image sensors. The FoM is applied to the studies from 1999 to 2018, which clarifies the trend of improvement as well as visualizes several breakthroughs in the development history.
关键词： modeling,CMOS image sensor (CIS),power efficiency,figure of merit (FoM),power consumption
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Auckland (2018.8.5-2018.8.8)] 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP) - Development of a 6-18GHz Quad-Ridged Flared Horn
摘要： In this paper, the cutoff frequency of the quad-ridge flared horn (QRFH) with respect to its ridge is studied. Based on the studies, we developed a QRFH to operate from 6 GHz to 18 GHz with high efficiency. The test results show that the return loss is less than -10 dB across the whole band. When the QRFH is used to illuminate a reflector antenna, the aperture efficiency is above 55.8%.
关键词： Low return loss,Cutoff frequency,Quad-ridge flared horn,High efficiency,Wideband
更新于2025-09-23 15:23:52