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Machine Learning for Tailoring Optoelectronic Properties of Single-Walled Carbon Nanotube Films
摘要： A machine learning technique, namely support vector regression, is implemented to enhance single-walled carbon nanotube (SWCNT) thin-film performance for transparent and conducting applications. We collected a comprehensive dataset describing the influence of synthesis parameters (temperature and CO2 concentration) on the equivalent sheet resistance (at 90% transmittance in the visible light range) for SWCNT films obtained by a semi-industrial aerosol (floating-catalyst) CVD with CO as a carbon source and ferrocene as a catalyst precursor. The predictive model trained on the dataset shows principal applicability of the method for refining synthesis conditions towards the advanced optoelectronic performance of multi-parameter processes such as nanotube growth. Further doping of the improved carbon nanotube films with HAuCl4 results in the equivalent sheet resistance of 39 Ω/□ – one of the lowest values achieved so far for SWCNT films.
关键词： transparent conductive films,support vector regression,single-walled carbon nanotubes,optoelectronic properties,machine learning
更新于2025-09-19 17:13:59
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Graphene Photonics || Optical Properties
摘要： The linear optical properties of graphene are considered in this chapter. Optoelectronic properties are considered in Chapter 4, and nonlinear optical properties are discussed in Chapter 5. All of these properties are related to the interactions between graphene and an optical field.
关键词： optoelectronic properties,optical properties,graphene,nonlinear optical properties
更新于2025-09-16 10:30:52
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Small-Molecule Donor/Polymer Acceptor Type Organic Solar Cells: Effect of Terminal Groups of Small-Molecule Donors
摘要： Small-molecule donor/polymer acceptor type (MD/PA-type) organic solar cells (OSCs) have the great advantage of superior thermal stability. However, very few small molecular donors can match polymer acceptors, leading to low power conversion ef?ciency (PCE) of MD/PA-type OSCs. In this work, we studied the effect of terminal groups of small molecular donors on the optoelectronic properties and OSC device performance of MD/PA-type OSCs. We select a benzodithiophene unit bearing carbazolyl substituents as the core, terthiophene as the bridging unit, and electron-withdrawing methyl 2-cyanoacetate, 3-ethylrhodanine, and 2H-indene-1,3-dione as the terminal groups to develop three small-molecule donors. With the increase of the electron-withdrawing capability of the terminal groups, the small molecular donors exhibit redshifted absorption spectra and downshifted LUMO levels. Among the three small-molecule donors, the one with 3-ethylrhodanine terminal group exhibits the best photovoltaic performance with the PCE of 8.0% in MD/PA-type OSCs. This work provides important guidelines for the design of small-molecule donors for MD/PA-type OSC applications.
关键词： organic solar cells,optoelectronic properties,Small-molecule donor
更新于2025-09-16 10:30:52
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Fluorinated dithienyl-diketopyrrolopyrrole: a new building block for organic optoelectronic materials
摘要： Diketopyrrolopyrrole (DPP) derivatives have been widely used as the electron-withdrawing unit to construct donor–acceptor (D–A) conjugated systems in organic electronics. The 3,6-position flanking aromatic rings of DPP could strongly influence the optoelectronic properties of DPP-based materials. In this study, a stepwise synthesis strategy was used to prepare monofluorinated and difluorinated dithienyl-DPP. The single crystal of the difluorinated model compound was also obtained. Three polymers based on bithiophene donor and dithienyl-DPP acceptor with different fluorinated positions were synthesized. And preliminary investigations of the influence of fluorination on the optoelectronic properties were performed.
关键词： dithienyl-DPP,Diketopyrrolopyrrole,optoelectronic properties,organic electronics,fluorinated
更新于2025-09-16 10:30:52
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Graphene Photonics || Optoelectronic Properties
摘要： In the preceding chapter, the surface optical conductivity eσeωT of graphene contributed by interband transitions was considered, which characterizes the optical response of graphene in the high-frequency region and has a real part given by (3.106) when the relaxation rate is taken to be zero by ignoring the finite relaxation times of the states involved in the transitions. We find by using this surface optical conductivity that monolayer graphene has an approximately constant absorbance of about 2.3 percent in the optical spectral region. However, in the low-frequency region, the surface optical conductivity eσeωT obtained in the preceding chapter is not valid. For example, if we set ω ? 0 for eσe0T to find the DC surface conductivity, we find that eσe0T is also zero, which is inconsistent with the DC surface conductivity obtained in Chapter 2. The discrepancy comes from the fact that eσeωT given in the preceding chapter only accounts for interband absorption of photons with electrons making transitions from a valence band to a conduction band, whereas the DC surface conductivity given in Chapter 2 is solely contributed by the intraband transitions of charge carriers within a valence band or within a conduction band.
关键词： Optoelectronic Properties,Surface Optical Conductivity,Intraband Transitions,Graphene,Interband Transitions
更新于2025-09-16 10:30:52
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Dibenzo[ <i>hi</i> , <i>st</i> ]ovalene as Highly Luminescent Nanographene: Efficient Synthesis via Photochemical Cyclodehydroiodination, Optoelectronic Properties, and Single-Molecule Spectroscopy
摘要： Dibenzo[hi,st]ovalene (DBOV), as a new nanographene, has demonstrated promising optical properties, such as red emission with a high fluorescence quantum yield of 79% and stimulated emission, as well as high thermal stability and photostability, which indicated its promise as a light-emitting and optical gain material. However, the previous synthetic routes required at least 12 steps. This obstructed access to different derivatives, e.g., to obtain crystals suitable for X-ray diffraction analysis and to tune the optoelectronic properties. Here, we report an efficient synthetic pathway to DBOV based on a sequential iodination-benzannulation of bi(naphthylphenyl)diyne, followed by photochemical cyclodehydroiodination (PCDHI). This protocol included a fused bischrysene as a key intermediate and furnished scalable amounts of meso-substituted DBOV derivatives with different substituents. DBOV with 2,6-dimethylphenyl groups could be used for single-crystal X-ray analysis, revealing the precise structure of the DBOV core. The optoelectronic properties of the DBOV derivatives were investigated by UV?vis absorption and fluorescence spectroscopy, cyclic voltammetry, and density functional theory calculations. Single-molecule spectroscopy at room and low temperatures provided novel insights into the photophysics of DBOV embedded in a polymer film. As a result of weak coupling of the optical transitions to the matrix, single-molecule emission spectra at 4.5 K showed narrow vibronic lines. The fluorescence autocorrelation function covering 9 orders of magnitude in time displayed high contrast photon antibunching and bunching, from which the fluorescence decay rate and the triplet population and depopulation rates could be retrieved. Remarkably, the intersystem crossing rate into the triplet state decreased by more than an order of magnitude at low temperature, demonstrating that temperature can be a crucial parameter to boost single photon emission of an aromatic hydrocarbon.
关键词： fluorescence quantum yield,nanographene,single-molecule spectroscopy,optoelectronic properties,photochemical cyclodehydroiodination
更新于2025-09-16 10:30:52
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Investigating the impact of thermal annealing on the photovoltaic performance of chemical bath deposited SnO2/p-Si heterojunction solar cells
摘要： The current work investigates the impact of annealing temperature on the optoelectronic properties of SnO2 thin films grown by chemical bath deposition (CBD) method. The as-grown SnO2 films, on p-Si substrate, are annealed at 200 °C and 400 °C for 10 min in Ar ambient for investigating the impact of such annealing on the performance of SnO2/p-Si heterojunction solar cells. The growth of a uniform SnO2 film on Si surface has been confirmed from SEM studies and the chemical composition and optical properties of the as-grown and annealed films are investigated in detail by employing XRD and ellipsometric measurements. Absorption coefficient of the samples is observed to vary in the range of 24 × 105 – 60 × 105/m, at its band gap (3.0 eV). The current–voltage characteristics under both dark and illuminated conditions suggest superior voltaic performance of the 200 °C annealed SnO2 film. The short-circuit current density, open-circuit voltage and fill-factor are obtained to be 0.45 mA/cm2, 5.41 mA/cm2 and 0.4 V, 0.34 V and 13%, 8% respectively for as-grown and 200 °C annealed samples. The maximum power conservation efficiency (η) of 4.9% is obtained for the 200 °C annealed sample. Thus, the study indicates the potential of CBD-grown SnO2 film for photovoltaic applications.
关键词： Optoelectronic properties,Heterojunction solar cells,Chemical bath deposition,Annealing temperature,SnO2 thin films
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Optoelectronic Properties of Tin-Based Hybrid Metal Halide Perovskite Thin Films for Photovoltaics
摘要： Due to their exceptional optoelectronic properties, hybrid metal halide perovskites films have shown extraordinary success as active layers in solar cells. One potential drawback of hybrid perovskites, however, is that the highest performing devices are currently based around toxic, lead-containing materials. Tin is a promising replacement for lead, p-doping in tin-based materials has prevented them from achieving the efficiencies of their lead-based analogues. Using optical-pump/THz-probe spectroscopy and THz time-domain spectroscopy, we compare the intrinsic and extrinsic optoelectronic properties formamidinium tin triiodide thin films and comment on the fundamental limits to charge transport.
关键词： tin-based hybrid metal halide perovskite,optoelectronic properties,photovoltaics,THz spectroscopy
更新于2025-09-12 10:27:22
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Tuning the optoelectronic properties of oligothiophenes for solar cell applications by varying the number of cyano and fluoro substituents for solar cell applications: A theoretical study
摘要： Chemical modifications through substitution are observed to be effective in controlling the optoelectronic properties of various polymers for different applications. In this study, density functional theory–based calculations are employed to investigate the optoelectronic properties of several oligothiophenes based on poly(3-hexylthiophene-2,5-diyl) by varying the number of fluoro and cyano substituents attached. The resulting structures of the polymer derivatives are affected by the electrostatic interactions between the cyano or fluoro groups and the adjacent thiophene unit. Of the two, cyano substitution results in much lower frontier orbital energies for the same number of substituents. It was observed that a decrease in the highest occupied molecule orbital and lowest unoccupied molecular orbital energies correlates very strongly with the number of cyano and fluoro substituents. The effect of the cyano and fluoro groups on the frontier orbitals is also demonstrated and observed to correlate strongly with a lowering of the highest occupied molecule orbital and lowest unoccupied molecular orbital energies as the number of substituents is varied. The predicted solar cell characteristics reveal that most cyano and fluoro derivatives will have improved characteristics compared to unsubstituted poly(3-hexylthiophene-2,5-diyl). This theoretical study shows that by varying the number of electron-withdrawing substituents, the optoelectronic properties may be tuned for solar cell applications.
关键词： density functional theory,optoelectronic properties,organic solar cells,conjugated polymers,computational chemistry
更新于2025-09-12 10:27:22
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New organic materiel based on benzothiadiazole for Photovoltaic application Solar Cells
摘要： In this work, we have studied conjugated polymers based on benzothiadiazole. the quantum chemical calculations on the structure and electronic and optics properties using the density functional theory (DFT), for the ground- and excited-state properties, respectively, using CAM-B3LYP and the 6-31G(d, p) basis set. These results will be devoted to the influence of the substitution benzothiadiazole on the electronic and optoelectronic properties of the polymer. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of these compounds were calculated and compared to LUMO of fullerenes,C60 [6,6]-phenyl- C61-butyric-acid methyl ester to estimate the effectiveness of these molecules as electron donors in bulk heterojunction (BHJ) small molecules-fullerene solar cells. The absorption energies have been obtained from TD-DFT calculations performed on the excited-state optimized S geometries. Finally, the theoretical results suggest that both the introduction of benzothiadiazole groups contribute significantly to the electronic and optoelectronic properties of the alternating donor–acceptor–donor conjugated systems studied.
关键词： Benzothiadiazole,BHJ,DFT,Optoelectronic properties,Photovoltaic cells
更新于2025-09-12 10:27:22