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Spectroscopic and Quantum-Chemical Studies of Halogen-Containing Derivatives of Poly-N-Epoxypropylcarbazole
摘要： The results of a study of the optical properties of conducting polymers, namely, derivatives of poly-N-epoxypropylcarbazole (PEPC) with heavy atoms, are presented. It is shown that a heavy atom in the structure of a polymer molecule leads to bathochromic shifts in the absorption, fluorescence, and phosphorescence spectra. This is a consequence of a decrease in the energy of the electron levels due to a change in the electron density distribution over the π-electron system in the chromophores of 2IPEPC and 3BrPEPC. Two bands can be distinguished in the fluorescence spectra of PEPC with heavy atoms, just as in the parent polymer. The emission band with a maximum at 380 nm belongs to the monomer luminescent centers and the long-wavelength emission with a maximum at about 420 nm to the polymer excimers. A heavy atom changes the ratio of the intensities of the monomer and excimer bands. The fluorescence lifetimes also decrease in the presence of a heavy atom. Quantum-chemical estimation of the intramolecular transition constants has shown that the probability of the singlet–triplet intercombination conversion in the halogen-containing PEPCs is higher in PEPC. This leads to a markedly stronger phosphorescence of the iodine and bromine-containing polymers and a shorter luminescence lifetime. The obtained results can be used in the development of composite materials based on photoconductive polymers for photovoltaics and optoelectronics.
关键词： optoelectronics,phosphorescence,conducting polymers,poly-N-epoxypropylcarbazole,fluorescence,heavy atoms,bathochromic shifts,photovoltaics,quantum-chemical estimation
更新于2025-09-23 15:21:21
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Recent progress in high-performance photo-detectors enabled by the pulsed laser deposition technology
摘要： In the past decade, photo-detectors have been demonstrated to have very important applications in image sensing, optical communication, fire detection, environmental monitoring, space exploration, safety detection, and many other scientific research and industrial technology fields and are regarded as the key components of wearable devices. Compared to traditional fabrication approaches, pulsed-laser deposition (PLD)-grown materials for photo-detectors offer several merits. First, PLD is a clean physical vapor deposition approach. A stoichiometric amount of atoms can be transferred from the target to the substrate, avoiding complicated and potentially dangerous chemical reactions. Furthermore, the PLD process is carried out in a high-vacuum environment. Therefore, almost no contaminants, such as catalysts, precursors, surfactants and by-products, will be introduced. Also, the thickness of the films can be controlled by simply manipulating the energy and pulse number of the pulsed laser. Furthermore, the fabrication temperature is relatively low, which is available to deposit materials on various substrates, even flexible ones. Most importantly, PLD is a deposition technology with large area coverage, which can produce centimeter-scale thin films, the planar geometry of which has significant potential for compact device integration with modern semiconductor techniques. Consequently, this review introduces the recent advances on the materials, fabrication, and application of pulsed-laser deposition for a variety of high-performance photo-detectors from an overall perspective. Moreover, the challenges and future development trends are discussed.
关键词： wearable devices,fabrication,optoelectronics,applications,photo-detectors,PLD,pulsed-laser deposition,high-performance,materials
更新于2025-09-23 15:21:01
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Gap Plasmon of Virus-Templated Biohybrid Nanostructures Uplifting the Performance of Organic Optoelectronic Devices
摘要： Plasmonic nanostructures, which exhibit prominent localized surface plasmon resonance (LSPR) properties, are highly desirable for organic solar cells (OSC) and organic light-emitting diode (OLED) devices. In the present work, novel plasmonic bio-nanostructures are successfully synthesized via the self-densification of silver (Ag) and gold (Au) metallic nanoparticles (NPs) onto a genetically engineered M13 bacteriophage template. Owing to the unique charge selectivity of the peptide receptors on the M13 bacteriophage, the metallic NPs can be directly anchored onto the bacteriophage through charge-driven interactions without binder/surfactant. The resulting Ag/AuNP-M13 bio-nanostructures display extraordinary gap-plasmon effect as well as tremendously enhanced LSPR properties than the randomly dispersed Ag/Au NPs. The incorporation of Ag/AuNP-M13 bio-nanostructures tremendously improves the performance of both OSC and OLED devices. Specifically, a power conversion efficiency increment of 15.5% is recorded for the phage-modified OSCs; whereas an external quantum efficiency increment of 22.6% is achieved for the phage-modified OLEDs. Based on this environmentally benign virus-template approach, various plasmonic/photonic bio-nanostructures can be designed for diverse device applications.
关键词： field-enhancement,optoelectronics,M13 bacteriophage,metamaterials,self-assembly,gap-plasmon effect
更新于2025-09-23 15:21:01
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Quantum-memory-enabled ultrafast optical switching in carbon nanotubes
摘要： Optical nonlinearities can be engineered into high-speed optical gates when a probe signal is switched coherently and fast by an optical control pulse through various nonlinear effects for switching. In semiconductors, strong light–matter interaction can also excite many electrons to interact with each other, which can deteriorate switching through Coulomb-induced dephasing. Here, we demonstrate that optical transmission of carbon nanotubes can be switched reversibly hundreds of times via detuned Rabi splitting, faster than 200 fs via nonresonant but strong control pulses. Our detailed experiment–theory analysis identifies that quantum memory in Coulombic scattering restores reversibility whilst simultaneously reducing undesirable pure dephasing of coherences. This capability creates new possibilities for ultrafast quantum optoelectronic processing in quantum materials.
关键词： carbon nanotubes,Ultrafast switching,quantum memory of many-body nonlinearilties,excitonic Stark shift,quantum optoelectronics
更新于2025-09-23 15:21:01
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Highly Conjugated, Fused-Ring, Quadrupolar Organic Chromophores with Large Two-Photon Absorption Cross-Sections in the Near-Infrared
摘要： The two-photon absorption (2PA) properties are investigated for two series of organic, π-conjugated, fused-ring, quadrupolar A-π-D-π-A chromophores of the type originally developed as non-fullerene acceptors for organic photovoltaics. These molecules are found to exhibit large nondegenerate two-photon absorption (ND2PA) cross-sections (ca. 6-27 × 103 GM) in the near infrared (NIR). In the first series, involving molecules of varying core size, ND2PA spectra and cross-sections characterized by femtosecond ND2PA spectroscopy in chloroform solutions reveal that increases in core size, and thus conjugation length, leads to substantially red-shifted and enhanced 2PA. In a second series, variation of the strength of the terminal acceptor (A) with constant core size (7 rings, indacene-based) led to less dramatic variation in the 2PA properties. Among the two core types studied, compounds in which the donor has a thieno[3,2-b]thiophene center demonstrate larger 2PA cross-sections than their indacene-centered counterparts, due to the greater electron-richness of their cores amplifying intramolecular charge transfer. Excited-state absorption (ESA) contributions to nonlinear absorption measured by open-aperture Z-scans are deduced for some of the compounds by analyzing the spectral overlap between 2PA bands and NIR ESA transitions obtained by ND2PA and transient absorption measurements, respectively. ESA cross-sections extracted from transient absorption and irradiance-dependent open-aperture Z-scans are in reasonable agreement and their moderate magnitudes (ca. 10-21 m2) suggest that, although ESA contributions are non-negligible, the effective response is predominantly instantaneous 2PA.
关键词： pump-probe spectroscopy,Nonlinear optics,Z-scan,organic optoelectronics,ultrafast spectroscopy,two-photon absorption
更新于2025-09-23 15:21:01
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Opportunities and challenges of interlayer exciton control and manipulation
摘要： Advances in van der Waals heterostructures allow the control of interlayer excitons by electrical and other means, promising exciting opportunities for high-temperature exciton condensation and valley–spin optoelectronics.
关键词： TMD bilayers,exciton condensation,van der Waals heterostructures,valley–spin optoelectronics,interlayer excitons
更新于2025-09-23 15:21:01
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2D Material Optoelectronics for Information Functional Device Applications: Status and Challenges
摘要： Graphene and the following derivative 2D materials have been demonstrated to exhibit rich distinct optoelectronic properties, such as broadband optical response, strong and tunable light–mater interactions, and fast relaxations in the flexible nanoscale. Combining with optical platforms like fibers, waveguides, grating, and resonators, these materials has spurred a variety of active and passive applications recently. Herein, the optical and electrical properties of graphene, transition metal dichalcogenides, black phosphorus, MXene, and their derivative van der Waals heterostructures are comprehensively reviewed, followed by the design and fabrication of these 2D material-based optical structures in implementation. Next, distinct devices, ranging from lasers to light emitters, frequency convertors, modulators, detectors, plasmonic generators, and sensors, are introduced. Finally, the state-of-art investigation progress of 2D material-based optoelectronics offers a promising way to realize new conceptual and high-performance applications for information science and nanotechnology. The outlook on the development trends and important research directions are also put forward.
关键词： transition metal dichalcogenides,optoelectronics,MXene,van der Waals heterostructures,information devices,graphene,black phosphorus,2D materials
更新于2025-09-23 15:21:01
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CMOS Nanophotonic Sensor with Integrated Readout System
摘要： The measurement of nanophotonic sensors currently requires the use of external measuring equipment for their read-out such as an optical spectrum analyzer, spectrophotometer, or detectors. This requirement of external laboratory-based measuring equipment creates a 'chip-in-a-lab' dilemma and hinders the use of nanophotonic sensors in practical applications. Making nanophotonic sensors usable in everyday life requires miniaturization of not only the sensor chip itself but also the equipment used for its measurement. In this paper, we have removed the need of external measuring equipment by monolithically integrating 1-D grating structures with a complementary metal-oxide-semiconductor (CMOS) integrated circuit having an array of photodiodes. By doing so, we get a direct electrical read-out of the refractive index changes induced when applying different analytes to grating structures. The gratings are made of CMOS compatible silicon nitride. Employing a nanophotonic sensor made of CMOS compatible material allows fabrication of the integrated sensor chip in a commercial CMOS foundry, enabling mass production for commercialization with low cost. Our results present a significant step toward transforming present laboratory-based nanophotonic sensors into practical portable devices to enable applications away from the analytical laboratory. We anticipate the work will have a major impact on technology for personalized medicine, environmental, and industrial sensing.
关键词： Diffraction gratings,nanophotonics,photodetectors,optoelectronics,sensors
更新于2025-09-23 15:21:01
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Optoelectronically suitable graphene oxide-decorated titanium oxide/polyaniline hybrid nanocomposites and their enhanced photocatalytic activity with methylene blue and rhodamine B dye
摘要： Organic–inorganic photocatalytic hybrid nanocomposites based on titanium oxide nanoparticle and polyaniline decorated with graphene oxide were synthesized via in situ chemical oxidative method using ammonium persulphate as an initiator and different weight percentages of TiO2 nanoparticles. The materials were characterized by using conventional techniques like UV–vis spectroscopy, FT-IR spectroscopy and X-ray diffraction. The electrical conductivity of the nanocomposites was found in the range of semiconducting materials. The nanocomposites possess broad application prospects covering the field of semiconducting devices, solar cells, sensors, microwave-absorbing materials and so on. The nanocomposites also exhibit promising photocatalytic activity towards degradation of methylene blue (MB) and rhodamine B dye in the presence of UV-light radiation. Compared to pure PANI and TiO2 nanoparticles, the GO/PANI/TiO2 nanocomposite showed much improvement in degradation efficiency. Significant photodegradation was observed with the molecules where 98.9% degradation was noted with 20% of TiO2 nanoparticles within 1 h under short-wavelength UV-light.
关键词： Fluorescence emitter,Photocatalysis,Optoelectronics,GO/PANI/TiO2 nanocomposite,TiO2 NPs,Semiconductor
更新于2025-09-23 15:21:01
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Polymer Controlled Growth and Wrapping of Perovskite Single Crystals Leading to Better Device Stability and Performance
摘要： Commodity scale polymer is used for controlling the nucleation and growth of single crystals of organolead halide perovskite. The polymer (polystyrene (PS)) cross-links and strongly interact with PbI2 and MAI (MAPbI3 perovskite precursors) resulting in the control of the crystallization process. The PS concentration modulates the nucleation time, crystal size and the number of perovskite single crystals. In addition, the PS based MAPbI3 crystals show an enhanced performance as well as improved thermal and environmental stability. Specifically, the PS-MAPbI3 crystals show 3 times higher photocurrent than plain MAPbI3 crystals and maintains a stable structure for more than 50 days (1200 h) under continuous 0.1 sun illumination in the air with a relative humidity of 40–45%. The improved performance and stability are attributed to the direct interaction between the PS and perovskite, which greatly reduces the ion migration, defect traps and charge recombination, and improves the carrier mobility and lifetime.
关键词： ion migration effect,photocurrent,perovskite,long-term stability,optoelectronics,crystal growth
更新于2025-09-23 15:21:01