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oe1(光电查) - 科学论文

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出版时间
  • 2019
研究主题
  • FSO Communication System
  • Subcarrier Intensity Modulation
  • Atmospheric Turbulence
  • Bit Error Rate
  • Average Irradiance
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Galgotias College of Engineering and Technology
347 条数据
?? 中文（中国） ▾

  • Enhancement in the efficiency of Sb2Se3 solar cells by adding low lattice mismatch CuSbSe2 hole transport layer

    摘要： As an excellent light absorbing material, antimony selenide (Sb2Se3) has attracted researchers to explore its application in solar cells. At present, the e?ciency of Sb2Se3 solar cells is still too low because of the low carrier concentration and high back surface recombination. In this study, we prepared an additional CuSbSe2 ?lm as hole transport layer by co-sputtering Sb2Se3 and Cu targets. It reduced the surface roughness of the absorption layer and the back surface recombination, which was bene?cial to the collection of carriers. Due to the higher carrier concentration of CuSbSe2 ?lm and proper di?usion of Cu, the carrier concentration of the absorption layer is greatly improved, thereby e?ectively increasing the Voc of the Sb2Se3 thin ?lm solar cells. Finally, we obtained a 5.87% e?ciency for the FTO/CdS/Sb2Se3/CuSbSe2/Au solar cell, which is more than 25% higher than the basic e?ciency.

    关键词： Carrier concentration,CuSbSe2,Co-sputtering,Sb2Se3,Lattice mismatch

    更新于2025-09-23 15:19:57

  • Parallelized and adaptive square-root unscented Kalman filter for carrier recovery in satellite-to-ground coherent optical communications

    摘要： An adaptive square-root unscented Kalman filter with a parallelized architecture for carrier recovery is proposed in QPSK based satellite-to-ground coherent optical communication systems. A new observation model is raised in the proposed scheme to make the state estimation more accurate. The process noise covariance (Q) and the measurement noise covariance (R) are adaptively estimated to make them consistent with their theoretical covariance. For verification of the feasibility of the proposed scheme, corresponding simulations of carrier recovery in satellite-to-ground laser links are carried out and compared with the scheme that is based on linear Kalman filter (LKF). The simulation results demonstrate that, compared with parallelized LKF, the proposed scheme has a wider range of block size and laser linewidth options, and it can relax the required transmit power by up to 0.5-3 dB under different zenith angle at the same BER. Moreover, the proposed scheme can achieve high estimation accuracy and fast tracking capability simultaneously in the case of dynamic frequency offset with better tolerance against the initial errors in Q and R.

    关键词： Atmospheric propagation,Adaptive Kalman filter,Free space optical communication,Coherent communications,Carrier recovery

    更新于2025-09-23 15:19:57

  • Synergistic enhancement in the microelectronic properties of poly-(dioctylfluorene) based Schottky devices by CdSe quantum dots

    摘要： This paper reports the potential application of cadmium selenide (CdSe) quantum dots (QDs) in improving the microelectronic characteristics of Schottky barrier diode (SBD) prepared from a semiconducting material poly-(9,9-dioctylfluorene) (F8). Two SBDs, Ag/F8/P3HT/ITO and Ag/F8-CdSe QDs/P3HT/ITO, are fabricated by spin coating a 10 wt% solution of F8 in chloroform and 10:1 wt% solution of F8:CdSe QDs, respectively, on a pre-deposited poly(3-hexylthiophene) (P3HT) on indium tin oxide (ITO) substrate. To study the electronic properties of the fabricated devices, current-voltage (I–V) measurements are carried out at 25 °C in dark conditions. The I–V curves of Ag/F8/P3HT/ITO and Ag/F8-CdSe QDs/P3HT/ITO SBDs demonstrate asymmetrical behavior with forward bias current rectification ratio (RR) of 7.42 ± 0.02 and 142 ± 0.02, respectively, at ± 3.5 V which confirm the formation of depletion region. Other key parameters which govern microelectronic properties of the fabricated devices such as charge carrier mobility (μ), barrier height (φb), series resistance (Rs) and quality factor (n) are extracted from their corresponding I–V characteristics. Norde’s and Cheung functions are also applied to characterize the devices to study consistency in various parameters. Significant improvement is found in the values of Rs, n, and RR by 3, 1.7, and 19 times, respectively, for Ag/F8-CdSe QDs/P3HT/ITO SBD as compared to Ag/F8/P3HT/ITO. This enhancement is due to the incorporation of CdSe QDs having 3-dimensional quantum confinement and large surface-to-volume area. Poole-Frenkle and Richardson-Schottky conduction mechanisms are also discussed for both of the devices. Morphology, optical bandgap (1.88 ± 0.5 eV) and photoluminescence (PL) spectrum of CdSe QDs with a peak intensity at 556 nm are also reported and discussed.

    关键词： poly-(9,9-dioctylfluorene),charge carrier mobility,Schottky barrier diode,microelectronic properties,CdSe quantum dots

    更新于2025-09-23 15:19:57

  • 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

  • Efficient Defect Passivation of Sb <sub/>2</sub> Se <sub/>3</sub> Film by Tellurium Doping for High Performance Solar Cells

    摘要： Defect in a semiconductor dictates carrier transport and recombination, which is one of the critical factors that influences the power conversion efficiency in solar cells. In this study, we demonstrate that the introduction of tellurium is able to fine tune the atomic ratio of Se/Sb in Sb2Se3 thin film, both Se-rich and Sb-rich Sb2Se3 are well obtained. On the ground of device fabrication and deep level defect spectroscopy characterization, we experimentally disclose that Se-rich Sb2Se3 favors the formation of SeSb and VSb defects, while Sb-rich condition benefits the formation of SbSe and VSe defects. With appropriately excess Se in Sb2Se3, a net efficiency improvement of 2% is obtained when compared with the pristine Sb2Se3 based solar cells. Our study provides an effective strategy to manipulate the defect formation in Sb2Se3 solar cell and inspires further improvement in the efficiency of Sb2Se3 solar cells.

    关键词： Sb2Se3,defect passivation,tellurium doping,solar cells,carrier transport

    更新于2025-09-23 15:19:57

  • Demodulation Technique Based on Laser Interference for Weak Photo-Acoustic Signals on Water Surface

    摘要： To detect underwater sound-generating targets, a water surface acoustic wave laser interference and signal demodulation technique is proposed in this paper. The underlying principle of this technique involves casting a laser beam onto the water surface disturbed by an underwater acoustic source and creating interference between lights re?ected by the surface and reference lights. A data acquisition and processing system was employed to obtain water surface acoustic wave information from the interference signals by means of demodulation, thus allowing detection of the underwater target. For the purpose of this study, an interference detection platform was set up in an optical dark chamber. High-frequency water surface ?uctuations were introduced in the reference optical path as the phase generated carriers to create laser interference signals in two different paths, which received demodulation based on an improved arc tangent demodulation algorithm and characteristic ratio algorithm, respectively, in view of their different frequencies. Water surface wave information was then derived from such low-frequency and high-frequency signals. According to test results, in the frequency range of 200 Hz–10 kHz, the frequency detection accuracy was better than 1 Hz. The amplitude measurements exhibited high repeatability, with a standard deviation lower than 2.5 nm. The theory proposed in this paper is therefore experimentally veri?ed with good results.

    关键词： optical interference,phase generated carrier,water surface acoustic waves,phase demodulation

    更新于2025-09-23 15:19:57

  • Simultaneous Power Conversion Efficiency and Stability Enhancement of Cs <sub/>2</sub> AgBiBr <sub/>6</sub> Leada??Free Inorganic Perovskite Solar Cell through Adopting a Multifunctional Dye Interlayer

    摘要： Perovskite solar cells (PSCs) are highly promising next-generation photovoltaic devices because of the cheap raw materials, ideal band gap of ≈1.5 eV, broad absorption range, and high absorption coefficient. Although lead-based inorganic-organic PSC has achieved the highest power conversion efficiency (PCE) of 25.2%, the toxic nature of lead and poor stability strongly limits the commercialization. Lead-free inorganic PSCs are potential alternatives to toxic and unstable organic-inorganic PSCs. Particularly, double-perovskite Cs2AgBiBr6-based PSC has received interests for its all inorganic and lead-free features. However, the PCE is limited by the inherent and extrinsic defects of Cs2AgBiBr6 films. Herein, an effective and facile strategy is reported for improving the PCE and stability by introducing an N719 dye interlayer, which plays multifunctional roles such as broadening the absorption spectrum, suppressing the charge carrier recombination, accelerating the hole extraction, and constructing an appropriate energy level alignment. Consequently, the optimizing cell delivers an outstanding PCE of 2.84%, much improved as compared with other Cs2AgBiBr6-based PSCs reported so far in the literature. Moreover, the N719 interlayer greatly enhances the stability of PSCs under ambient conditions. This work highlights a useful strategy to boost the PCE and stability of lead-free Cs2AgBiBr6-based PSCs simultaneously, accelerating the commercialization of PSC technology.

    关键词： charge carrier separation,dye interlayer,Cs2AgBiBr6,energy level alignment,perovskite solar cell

    更新于2025-09-23 15:19:57

  • [IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Performance of silicon heterojunction solar cells using high resistivity substrates

    摘要： We investigate the potential advantages of using very high resistivity n- and p-type, to manufacture high performance solar cells. Analytical modeling indicates that high resistivity substrates (10 Ωcm - >1k Ωcm) are required to have bulk Shockley-Read-Hall lifetimes in the millisecond range to outperform wafers with standard resistivities (< 10 Ωcm). Additionally, for resistivities over 10 Ω.cm, efficiencies show to be weakly dependent of the bulk resistivity. These results if experimental verified, can lead to more affordable manufacturing, by lessening the requirements of dopants homogeneity along the ingot. We successfully passivated both n- and p- type substrates using i-a-Si:H, obtaining surface saturation current densities below 10 fAcm-2 and effective minority-carrier lifetimes over 2 ms at maximum power over the entire range of bulk resistivities (3 Ωcm- >10k Ωcm).

    关键词： photovoltaic cells,doping,charge carrier lifetime,silicon,amorphous materials

    更新于2025-09-23 15:19:57

  • Ultra-long carrier lifetime in neutral graphene-hBN van der Waals heterostructures under mid-infrared illumination

    摘要： Graphene/hBN heterostructures are promising active materials for devices in the THz domain, such as emitters and photodetectors based on interband transitions. Their performance requires long carrier lifetimes. However, carrier recombination processes in graphene possess sub-picosecond characteristic times for large non-equilibrium carrier densities at high energy. An additional channel has been recently demonstrated in graphene/hBN heterostructures by emission of hBN hyperbolic phonon polaritons (HPhP) with picosecond decay time. Here, we report on carrier lifetimes in graphene/hBN Zener-Klein transistors of ~30 ps for photoexcited carriers at low density and energy, using mid-infrared photoconductivity measurements. We further demonstrate the switching of carrier lifetime from ~30 ps (attributed to interband Auger) down to a few picoseconds upon ignition of HPhP relaxation at finite bias and/or with infrared excitation power. Our study opens interesting perspectives to exploit graphene/hBN heterostructures for THz lasing and highly sensitive THz photodetection as well as for phonon polariton optics.

    关键词： photodetectors,mid-infrared,phonon polaritons,van der Waals heterostructures,THz,Graphene,carrier lifetime,hBN

    更新于2025-09-23 15:19:57

  • Hund excitations and the efficiency of Mott solar cells

    摘要： We study the dynamics of photoinduced charge carriers in semirealistic models of LaVO3 and YTiO3 polar heterostructures. It is shown that two types of impact ionization processes contribute to the carrier multiplication in these strongly correlated multiorbital systems: The first mechanism involves local spin state transitions, while the second mechanism involves the scattering of high-kinetic-energy carriers. Both processes act on the 10-fs timescale and play an important role in the harvesting of high-energy photons in solar cell applications. As a consequence, the optimal gap size for Mott solar cells is substantially smaller than for semiconductor devices.

    关键词： LaVO3,Mott solar cells,impact ionization,YTiO3,carrier multiplication

    更新于2025-09-23 15:19:57