- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Numerical analysis of single-point spectroscopy curves used in photo-carrier dynamics measurements by Kelvin probe force microscopy under frequency-modulated excitation
摘要： In recent years, the investigation of the complex interplay between the nanostructure and photo-transport mechanisms has become of crucial importance for the development of many emerging photovoltaic technologies. In this context, Kelvin probe force microscopy under frequency-modulated excitation has emerged as a useful technique for probing photo-carrier dynamics and gaining access to carrier lifetime at the nanoscale in a wide range of photovoltaic materials. However, some aspects about the data interpretation of techniques based on this approach are still the subject of debate, for example, the plausible presence of capacitance artifacts. Special attention shall also be given to the mathematical model used in the data-fitting process as it constitutes a determining aspect in the calculation of time constants. Here, we propose and demonstrate an automatic numerical simulation routine that enables to predict the behavior of spectroscopy curves of the average surface photovoltage as a function of a frequency-modulated excitation source in photovoltaic materials, enabling to compare simulations and experimental results. We describe the general aspects of this simulation routine and we compare it against experimental results previously obtained using single-point Kelvin probe force microscopy under frequency-modulated excitation over a silicon nanocrystal solar cell, as well as against results obtained by intensity-modulated scanning Kelvin probe microscopy over a polymer/fullerene bulk heterojunction device. Moreover, we show how this simulation routine can complement experimental results as additional information about the photo-carrier dynamics of the sample can be gained via the numerical analysis.
关键词： Kelvin probe force microscopy,nanostructured photovoltaics,numerical simulations,photo-carrier dynamics,carrier dynamics,carrier recombination,carrier lifetime
更新于2025-09-23 15:22:29
-
Photoluminescence Flickering and Blinking of Single CsPbBr <sub/>3</sub> Perovskite Nanocrystals: Revealing Explicit Carrier Recombination Dynamics
摘要： In order to obtain an in-depth understanding of the dynamics and mechanism of carrier recombination in CsPbBr3 nanocrystals (NCs), we have investigated the photoluminescence (PL) of this material at the single particle level using time-tagged-time-resolved method. The study reveals two distinct types of PL fluctuations of the NCs, which are assigned to flickering and blinking. The flickering is found to be due to excess surface trap on the NCs and the flickering single particles are transformed into blinking ones with significant enhancement of PL intensity and stability on post-synthetic surface treatment. Intensity correlated lifetime analysis of the PL time-trace reveals both trap-mediated nonradiative band edge carrier recombination and positive trion recombination in single NCs. Dynamical and statistical analysis suggests a diffusive nature of the trap states to be responsible for the PL intermittency of the system. These findings throw light on the nature of the trap states, reveal the manifestation of these trap states in PL fluctuation and provide an effective way to control the dynamics of CsPbBr3 NCs.
关键词： CsPbBr3,Surface Treatment,Carrier Recombination,Photoluminescence,Nanocrystals
更新于2025-09-23 15:21:21
-
Improvement of Cu(In,Ga)Se <sub/>2</sub> solar cell performance by thiourea treatment
摘要： We investigated the effects of a thiourea treatment performed to the absorber of Cu(In,Ga)Se2 (CIGS) solar cells. The thiourea treatment successfully improved the open-circuit voltage, fill factor, and conversion efficiency of the solar cells. Reduced ideality factor and reverse saturation current density demonstrated that the suppression of carrier recombination contributed to the improvement in solar cell performance. Increased intensity in cross-sectional electron-beam-induced current measurements confirmed the improved film quality with the thiourea treatment. Additionally, an enhanced carrier density observed with the treatment suggests the passivation of donor-type defects. These results indicate that the thiourea treatment is promising to improve the absorber quality and enhance the performance of CIGS solar cells.
关键词： thiourea treatment,solar cell,Cu(In,Ga)Se2,carrier recombination,film quality
更新于2025-09-23 15:21:01
-
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
-
Transparent Electrode and Buffer Layer Combination for Reducing Carrier Recombination and Optical Loss Realizing over a 22%-Efficient Cd-Free Alkaline-Treated Cu(In,Ga)(S,Se) <sub/>2</sub> Solar Cell by the All-Dry Process
摘要： Structures of (K or Cs) alkaline-treated Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells are developed, and their carrier recombination rates are scrutinized. It is determined that short-circuit current density (JSC) is enhanced (decreased optical loss), when ZnS(O,OH), (Cd,Zn)S, and Zn0.8Mg0.2O buffers with large band-gap energy (Eg) are applied as replacement of CdS buffer. The JSC is further increased, more reducing the optical loss, when Zn0.9Mg0.1O:B is used as transparent conductive oxide (TCO) with larger Eg and lower free carrier absorption than those of ZnO:Al. Furthermore, all carrier recombination rates throughout the devices with K or Cs treatment, especially at buffer/absorber interface and in quasi neutral region, are reduced, thereby reducing open-circuit voltage deficit (VOC,def), well consistent with the simulated ones. The carrier recombination rate at the buffer/absorber interface is further decreased, when the CdS and (Cd,Zn)S buffers, deposited by chemical bath deposition, are applied, leading to the more reduction of the VOC,def and the high conversion efficiency (η) of about 21%. Under the trade-off between VOC,def and optical loss, the highest η of 22.6% is attained with the lowest power loss (or the highest VOC × JSC) in the Cs-treated Cd-free CIGSSe solar cell with an optimized structure of glass/Mo/CIGSSe/Zn0.8Mg0.2O/Zn0.9Mg0.1O:B, fabricated by all-dry process, where the Zn0.8Mg0.2O buffer is prepared by the sputtering method. This occurs because the JSC is the highest attributable to the larger Eg of Zn0.8Mg0.2O buffer than those of the CdS and (Cd,Zn)S.
关键词： Zn1-xMgxO,Zn1-xMgxO:Al,Cu(In,Ga)(S,Se)2 thin-film solar cell,carrier recombination rates,Zn1-xMgxO:B,(Cd,Zn)S
更新于2025-09-23 15:19:57
-
Direct-indirect GeSn band structure formation by laser Radiation: The enhancement of Sn solubility in Ge
摘要： Low equilibrium solid solubility of Sn atoms in Ge (less than 1%) leads to limitations in application of this material for IR detectors and emitters. Providing of non-equilibrium conditions by powerful pulsed laser radiation can be successfully applied for enhancement of solubility of impurity atoms in the host material. Here we present laser-induced monotonous redistribution of Sn atoms in Ge, based on the thermogradient effect aiming overcoming equilibrium limitations in the solubility. We applied pulsed nanosecond laser radiation to epitaxial Ge0.96Sn0.04 layer grown on Si substrate to increase Sn atomic concentration up to 14% at the surface layer. As a result, indirect-direct graded bandgap GeSn structure was formed. The TEM/EDS cross-section analysis, X-ray photoelectron spectroscopy, Raman and UV reflection spectra confirmed the increase of Sn atomic content at the surface by order of magnitude. SEM and AFM imaging provided evident microstructure changes, while carrier lifetime changes, determined by differential transmittivity, were not observed, indicating that laser irradiation does not generate defects which reduce electronic quality of the material.
关键词： Laser radiation,Thermogradient effect,Solid solution,Carrier recombination,GeSn
更新于2025-09-23 15:19:57
-
[IEEE 2019 2nd International Conference on Power and Embedded Drive Control (ICPEDC) - Chennai, India (2019.8.21-2019.8.23)] 2019 2nd International Conference on Power and Embedded Drive Control (ICPEDC) - Efficient Electron Carrier distribution of n+ MoS <sub/>2</sub> /i-MoS <sub/>2</sub> /p-Si Heterojunction Solar Cell
摘要： In this paper, modeling and simulation study of energy harvested nano electronics of PV device and its functions under different light intensity have been discussed. The emitter layer of the proposed solar cell has been designed to enhance the photocurrent efficiency even at low electric field. The Electron-hole pair generation of the proposed model is increased to 4.9*1028 [1/ (m2*s)] due to optimized intrinsic MoS2 layer thickness. As a result, the charge carriers distribution enhanced the carrier collection efficiency in the absorber layer. This study reveals that the proposed Energy harvesting device Open-circuit Voltage(Voc) and Short circuit Current density(Jsc) are 1.982[V], 31.22[mA/cm2] respectively and its efficiency found to be 31.91 %. These simulations showed that can be environmental stability and excellent carrier distribution solar cell.
关键词： electric field,efficiency-region,charge-carrier recombination,Photogeneration,n+MoS2
更新于2025-09-23 15:19:57
-
Janus Chromium Dichalcogenides Monolayers with Low Carrier Recombination for Photocatalytic Overall Water-Splitting under Infrared Light
摘要： Photocatalytic overall water-splitting is known as one of most promising methods to alleviate energy crisis. Searching for stable and efficient photocatalysts plays a critical role in this process. Here, we propose a novel class of Janus chromium dichalcogenides (CrXY, X/Y = S, Se, Te) monolayers serving as efficient photocatalysts for overall water-splitting under infrared light irradiation. We reveal that these Janus monolayers harbor an intrinsic dipole, which promotes the spatial separation of photo-generated carriers. More significantly, these systems exhibit suitable band gaps as well as band edge positions, enabling preeminent infrared optical absorption and high carrier mobility. Furthermore, the nonradiative recombination of photoinduced charge carriers in CrXY monolayers are evaluated based on time-domain density functional theory. The obtained long-lived excited carriers (~ 2 ns) are even comparable with that in transition-metal dichalcogenides heterostructures, which benefits for the photocatalytic reaction with high efficiency. Our results provide a new guidance for designing brand new photocatalytic systems with broad optical absorption and low carrier recombination.
关键词： infrared light,first principles calculations,carrier recombination,Janus chromium dichalcogenides,photocatalytic water-splitting
更新于2025-09-19 17:15:36
-
Understanding the Defect Properties of Quasi-2D Halide Perovskites for Photovoltaic Applications
摘要： Quasi-2D halide perovskites have emerged as one of the most promising photovoltaic materials owing to their excellent stability, yet the device power conversion efficiency (PCE) is far from satisfactory. Beside of crystal orientation related carrier transport, defects in absorbers also play a crucial role in device performance, which receives limited attention in the 2D perovskite field. Herein we systematically profiled the defects states in 2D perovskite film by the temperature-dependent admittance spectroscopy (AS), light-intensity-dependent VOC, space-charge-limited-circuit (SCLC), and photoluminescence measurements. It is revealed that the Quasi-2D perovskite films suffer from severe defects as compared to the 3D counterparts in terms of both trap energy levels and trap densities. Consequently, nonradiative recombination of photogenerated carriers is much greater in the corresponding devices, wherein the monomolecular recombination is dominant. These findings substantially benefit a deeper understanding of the nature of 2D perovskite materials, which promotes the further design of 2D perovskite solar cells.
关键词： carrier recombination,Quasi-2D halide perovskites,defects properties,photovoltaic materials,solar cells
更新于2025-09-19 17:13:59
-
Incorporation of metal selenide thin films as the secondary absorber in the CdTe solar cells
摘要： The introduction of selenium in the CdTe solar cells has been responsible for high performance CdTe thin film solar cells in recent years. It is an approach to form CdSexTe1-x alloys by the interdiffusion using precursor CdSe layer during the CdTe high-temperature deposition process. Nevertheless, the compositionally gradient CdSexTe1-x formed by the diffusion makes it difficult to absorb long-wavelength photons adequately. So close-spaced sublimation deposited CdSexTe1-x interlayer was incorporated in the CdTe thin film solar cells. It is found that 600 nm CdSexTe1-x absorber is useful to increase long-wavelength photons absorption and extend the long-wavelength QE response. Meanwhile, the synergetic effects of the primary absorber deposition processing on CdTe solar cell performance were investigated. The substrate temperature of CdTe deposition has an obvious impact on the cell efficiency. The much higher substrate temperature can efficiently gain larger grain size, increase the crystal quality and promote the interdiffusion of different semiconductor layers. These improvements can efficiently decrease the carrier recombination to obtain a much higher fill factor and open-circuit voltage.
关键词： Spectral response,CdTe solar cells,Carrier recombination,CdSexTe1-x,CdSe
更新于2025-09-19 17:13:59