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A Narrow-Bandgap n-Type Polymer Semiconductor Enabling Efficient All-Polymer Solar Cells
摘要： Currently, n-type acceptors in high-performance all-polymer solar cells (all-PSCs) are dominated by imide-functionalized polymers, which typically show medium bandgap. Herein, a novel narrow-bandgap polymer, poly(5,6-dicyano-2,1,3-benzothiadiazole-alt-indacenodithiophene) (DCNBT-IDT), based on dicyanobenzothiadiazole without an imide group is reported. The strong electron-withdrawing cyano functionality enables DCNBT-IDT with n-type character and, more importantly, alleviates the steric hindrance associated with typical imide groups. Compared to the benchmark poly(naphthalene diimide-alt-bithiophene) (N2200), DCNBT-IDT shows a narrower bandgap (1.43 eV) with a much higher absorption coefficient (6.15 × 104 cm?1). Such properties are elusive for polymer acceptors to date, eradicating the drawbacks inherited in N2200 and other high-performance polymer acceptors. When blended with a wide-bandgap polymer donor, the DCNBT-IDT-based all-PSCs achieve a remarkable power conversion efficiency of 8.32% with a small energy loss of 0.53 eV and a photoresponse of up to 870 nm. Such efficiency greatly outperforms those of N2200 (6.13%) and the naphthalene diimide (NDI)-based analog NDI-IDT (2.19%). This work breaks the long-standing bottlenecks limiting materials innovation of n-type polymers, which paves a new avenue for developing polymer acceptors with improved optoelectronic properties and heralds a brighter future of all-PSCs.
关键词： polymer acceptors,high absorption coefficient,dicyanobenzothiadiazole,narrow bandgap,all-polymer solar cells
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Computational and Characterization Techniques in Engineering & Sciences (CCTES) - Lucknow, India (2018.9.14-2018.9.15)] 2018 International Conference on Computational and Characterization Techniques in Engineering & Sciences (CCTES) - Analysis of Current Density, Absorption Coefficient for Increasing the Efficiency of Solar Cell by using GaAs as Substrate
摘要： In this paper, a mathematical modeling of graphene gated graphene GaAs Schottky Junction field effect solar cell has been conducted to obtain J-V curve which is the benchmarked of my research and the characteristics is compared by simulating layers of different semiconductor materials to obtain graphene based solar cell by using Silvaco Atlas tool. Numerical simulation of graphene based Schottky junction solar cells to identify possible future applications of graphene. Copper indium gallium diselenide. Cadmium telluride and amorphous silicon are chosen as the semiconductor bases because of their high absorption coefficient, high / tunable band gap, and the possibility for economical fabrication as compared to single crystal silicon technology.
关键词： carrier generation rate,absorption coefficient,Graphene based solar cell,energy of the photon,power density
更新于2025-09-11 14:15:04
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Ultranarrow-waveguide AlGaAs/GaAs/InGaAs lasers
摘要： We have designed, fabricated and studied ultranarrow-waveguide heterostructure lasers emitting in the spectral range 1000 – 1100 nm. The lasers have been characterised by current – voltage, light – current, far-field intensity distribution and internal optical loss measurements. The ultranarrow-waveguide lasers have been shown to have a threshold current density of ~75 A cm–2, internal quantum efficiency near 100 % and internal optical loss near the lasing threshold under 1 cm–1, which corresponds to the level of standard heterostructures. We have demonstrated the possibility of obtaining up to 5 W of output power in continuous mode and up to 30 W in pulsed mode, with a beam convergence (FWHM) of 17.8°. The slope of the internal optical loss as a function of pump current for the ultranarrow-waveguide lasers can be markedly lower than that in lasers with a standard design, but internal quantum efficiency drops to 40 % with increasing pump current. The use of barrier layers in ultranarrow-waveguide lasers makes it possible to substantially reduce the drop in internal quantum efficiency.
关键词： absorption coefficient,internal optical loss,ultranarrow waveguide,energy barrier,pulsed pumping,semiconductor laser
更新于2025-09-11 14:15:04
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Improved banded method for spectral thermal radiation in participating media with spectrally dependent wall emittance
摘要： To develop an efficient and practical spectral radiation model for CFD simulations, a banded approach is proposed for a mixture of carbon dioxide and water vapor in varying thermodynamic states. Using a previously reported band dividing scheme, a statistical narrow band model is implemented to provide gray band absorption coefficient databases. The databases were then approximated by certain simple correlations, which can be readily used in CFD calculations of RTE solvers. The correlations were validated in several 1D and 3D benchmarks representing various combustion conditions. The accuracy and CPU cost of the proposed banded approach were studied and compared with those of other similar methods. The results demonstrated that the new approach is an efficient and accurate method that can be conveniently applied in a commercial CFD code for spectral radiation; moreover, it can handle non-gray walls. As a practical case study, the proposed approach was used to simulate radiative heat transfer within a back pass channel of a CFB boiler. The effect of combustion scenarios, i.e., air- and oxygen-fired, boiler load, inlet flow conditions, and wall material, was analyzed by the CFD model. The predictions of two different RTE solvers, i.e., P1 and DO, and the required CPU time were compared for gray and non-gray models.
关键词： Non-gray wall,Back pass channel,CFB boiler,Radiation heat transfer,Band absorption coefficient,Narrow band calculation,Non-gray gas modeling,Banded approach
更新于2025-09-11 14:15:04
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Investigation of nonlinear absorption and the electromagnetically induced transparency in a SMNP-SQD hybrid system by using the Mie theory
摘要： By using the Mie theory, nonlinear absorption coefficient and electromagnetically induced transparency (EIT) of a hybrid system consisting of GaAs spherical quantum dot (SQD) with ladder model and parabolic potential in the vicinity of a spherical metal nanoparticle (SMNP) are investigated. The density matrix equations in steady-state are solved and the third order susceptibility is obtained. Then, by using imaginary part of third order susceptibility, the nonlinear absorption coefficient are computed. Then, the effects of radii of SQD and SMNP, distance between SQD and SMNP and control laser frequency on nonlinear absorption coefficient and electromagnetically induced transparency (EIT) are investigated.
关键词： Metal nanoparticle,Mie theory,Spherical quantum dot,Electromagnetically induced transparency,Absorption coefficient
更新于2025-09-10 09:29:36
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Spectroscopic Microtomography in the Visible Wavelength Range
摘要： We demonstrate spectroscopic microtomography in the visible wavelength range (450–700 nm) using digital holographic tomography, a wavelength-scanning source, and a variable-optical-path-length strategy. This multidimensional imaging system can directly measure the absorption-coefficient and refractive-index spectra of a three-dimensional specimen. We apply the system developed to characterize three types of polystyrene beads (undyed, blue dyed, and red dyed) as well as oxygenated and deoxygenated single red blood cells.
关键词： visible wavelength range,absorption-coefficient,digital holographic tomography,refractive-index spectra,spectroscopic microtomography
更新于2025-09-10 09:29:36
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Noise Analysis of Group IV Material-Based Heterojunction Phototransistor for Fiber-Optic Telecommunication Networks
摘要： This paper presents an analytical study of noise behavior and spectral responsivity of Ge1?xSnx alloy-based heterojunction phototransistors (HPTs) for different Sn compositions and base doping concentrations. The structure consists of n-Ge/p-Ge1?xSnx layers pseudomorphically grown on Si substrate via Ge virtual substrate, compatible with complementary metal-oxide-semiconductor technology. The high absorption coefficient of the alloy in base significantly improves signal-to-noise ratio in the high-frequency region, leading to efficient photodetection in the C- and L-bands of fiber-optic telecommunication window. A comparison is made between the theoretical findings for GeSn HPTs and the available data for currently employed group III–V compound-based HPTs, to examine if GeSn-based HPT can be a good alternative.
关键词： GeSn alloys,absorption coefficient,spectral responsivity,heterojunction phototransistor,signal-to-noise ratio
更新于2025-09-09 09:28:46
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The third-order nonlinear optical properties of gold nanoparticles-methylene blue conjugation
摘要： Third-order nonlinear properties of a thiazine dye (methylene blue (MB)) and a plasmonic nanoparticle (gold nanoparticles (GNPs)) have been studied by Z-scan method with a 50 mW continues wave (CW) diode pumped solid state laser (DPSSL) operating at 532 nm. The nonlinear parameters (nonlinear refractive (NLR) index (n2) and nonlinear absorption (NLA) coefficient (β)) are determined. The mechanism of the observed NLA and nonlinear refraction is attributed respectively to reverse saturable absorption (RSA) and thermal nonlinear effects. The magnitude of the measured NLR index (n2) and NLA coefficient (β) are founded to be the order of 10?8 cm2/W and 10?4 cm/W respectively. The effect of MB and GNPs on each other has been studied. Z-scan experiments for GNPs-MB conjugation shows noticeable increase in nonlinear parameters.
关键词： Z-scan method,Metal nanoparticles,Nonlinear optics,Organic dye,Nonlinear refractive index,Nonlinear absorption coefficient
更新于2025-09-09 09:28:46
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Multiple scattering correction factor estimation for aethalometer aerosol absorption coefficient measurement
摘要： We estimate the multiple scattering correction factor (????????), which is an empirical constant required to correct aerosol absorption coefficient (??????) measurements for the multiple scattering artefacts of aethalometer, using a multiplier derived from a linear regression method ( ???????? ?????? ). Estimated ???????? ?????? values during the Cheju ABC Plume Monsoon EXperiment (CAPMEX) are 3.99 (405 nm), 4.48 (532 nm), and 5.46 (781 nm) using aethalometer and 3-wavelength PhotoAcoustic Soot Spectrometer (PASS-3). The difference between these ???????? ?????? values and those of a previous study ( ???????? ??03 ; Weingartner et al. 2003) are -8.0% (405 nm), 20.1% (532 nm), and 30.2% (781 nm); the larger. ???????? difference is greater at larger wavelengths because the linear regression line intercept is ??03 varies by up to 121% with increasing aerosol absorption coefficient (??????) ?????? determined ?????? varies by only 36.8%. ???????? ??03 and ???????? ??03 ?????? ??03 and ?????? ??03 and ?????? from ?????? ?????? and ?????? ??03 and ?????? ???????? than ?????? agrees better with ?????? ????????. This suggest that square difference of ?????? ???????? are -23.1 and 25.8%; however, those of ?????? ???????? are -9.0 and 17.9%, respectively. LLN and ALT both exhibit a greater Absorption Photometer (CLAP; ?????? ??03 from ?????? ???????? than between ?????? difference between ?????? ?????? can be applied to year-round aethalometer measurements. Furthermore, ?????? ???????? during CAPMEX were applied to year-round aethalometer ?????? measurements (?????? ??????, respectively) at Gosan (GSN), Lulin (LLN), and Alert (ALT) stations. ?????? ?????? were compared to concurrent ?????? measurements from Continuous Light ????????). At GSN, the bias difference and root mean ??03 in all three environments.
关键词： CLAP,multiple scattering correction factor,aerosol absorption coefficient,PASS-3,aethalometer
更新于2025-09-09 09:28:46
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Experimental Characterization of Artificial Human Skin with Melanomas for Accurate Modelling and Detection in Healthcare Application
摘要： A preliminary investigation is carried out on the artificial human skin tissues with and without metastatic melanomas using Terahertz Time Domain Spectroscopy (THz-TDS). Both the refractive indexes and absorption coefficients of artificial skin with melanomas are higher than the normal artificial skin samples over the entire frequency range between 0.2 THz to 1.6 THz. The reason is that tumour cells degrade the in contraction of fibroblasts causing more water content malignant tissues. This study quantifies the impact of melanomas on the optical parameters of artificial skin tissue and can help in techniques that will diagnose and prevent tumours at the early stage.
关键词： artificial human skin,absorption coefficient,Terahertz Time Domain Spectroscopy,refractive index,melanomas
更新于2025-09-04 15:30:14