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- Item1D p–n Junction Electronic and Optoelectronic Devices from Transition Metal Dichalcogenide Lateral Heterostructures Grown by One-Pot Chemical Vapor Deposition Synthesis(Weinheim : Wiley-VCH, 2021) Najafidehaghani, Emad; Gan, Ziyang; George, Antony; Lehnert, Tibor; Ngo, Gia Quyet; Neumann, Christof; Bucher, Tobias; Staude, Isabelle; Kaiser, David; Vogl, Tobias; Hübner, Uwe; Kaiser, Ute; Eilenberger, Falk; Turchanin, AndreyLateral heterostructures of dissimilar monolayer transition metal dichalcogenides provide great opportunities to build 1D in-plane p–n junctions for sub-nanometer thin low-power electronic, optoelectronic, optical, and sensing devices. Electronic and optoelectronic applications of such p–n junction devices fabricated using a scalable one-pot chemical vapor deposition process yielding MoSe2-WSe2 lateral heterostructures are reported here. The growth of the monolayer lateral heterostructures is achieved by in situ controlling the partial pressures of the oxide precursors by a two-step heating protocol. The grown lateral heterostructures are characterized structurally and optically using optical microscopy, Raman spectroscopy/microscopy, and photoluminescence spectroscopy/microscopy. High-resolution transmission electron microscopy further confirms the high-quality 1D boundary between MoSe2 and WSe2 in the lateral heterostructure. p–n junction devices are fabricated from these lateral heterostructures and their applicability as rectifiers, solar cells, self-powered photovoltaic photodetectors, ambipolar transistors, and electroluminescent light emitters are demonstrated. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH
- ItemSpectrometer‐free Optical Hydrogen Sensing Based on Fano‐like Spatial Distribution of Transmission in a Metal−Insulator−Metal Plasmonic Doppler Grating(Weinheim : Wiley-VCH, 2021) Chen, Yi‐Ju; Lin, Fan‐Cheng; Singh, Ankit Kumar; Ouyang, Lei; Huang, Jer‐ShingOptical nanosensors are promising for hydrogen sensing because they are small, free from spark generation, and feasible for remote optical readout. Conventional optical nanosensors require broadband excitation and spectrometers, rendering the devices bulky and complex. An alternative is spatial intensity-based optical sensing, which only requires an imaging system and a smartly designed platform to report the spatial distribution of analytical optical signals. Here, a spatial intensity-based hydrogen sensing platform is presented based on Fano-like spatial distribution of the transmission in a Pd-Al2O3-Au metal-insulator-metal plasmonic Doppler grating (MIM-PDG). The MIM-PDG manifests the Fano resonance as an asymmetric spatial transmission intensity profile. The absorption of hydrogen changes the spatial Fano-like transmission profiles, which can be analyzed with a “spatial” Fano resonance model and the extracted Fano resonance parameters can be used to establish analytical calibration lines. While gratings sensitive to hydrogen absorption are suitable for hydrogen sensing, hydrogen insensitive gratings are also found, which provide an unperturbed reference signal and may find applications in nanophotonic devices that require a stable optical response under fluctuating hydrogen atmosphere. The MIM-PDG platform is a spectrometer-free and intensity-based optical sensor that requires only an imaging system, making it promising for cellphone-based optical sensing applications. © 2021 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH.
- ItemEmission Manipulation by DNA Origami‐Assisted Plasmonic Nanoantennas(Weinheim : Wiley-VCH, 2021) Yeşilyurt, Ayşe Tuğça Mina; Huang, Jer‐ShingPlasmonic nanoantennas mediate far and near optical fields and confine the light to subwavelength dimensions. The spatial organization of nanoantenna elements is critical as it affects the interelement coupling and determines the resultant antenna mode. To couple quantum emitters to optical antennas, high precision on the order of a few nm with respect to the antenna is necessary. As an emerging nanofabrication technique, DNA origami has proven itself to be a robust nanobreadboard to obtain sub-5 nm positioning precision for a diverse range of materials. Eliminating the need for expensive state-of-the-art top-down fabrication facilities, DNA origami enables cost-efficient implementation of nanoscale architectures, including novel nanoantennas. The ability of DNA origami to deterministically position single quantum emitters into nanoscale hotspots further boosts the efficiency of light–matter interaction controlled via optical antennas. This review recapitulates the recent progress in plasmonic nanoantennas assisted by DNA origami and focuses on their various configurations. How those nanoantennas act on the emission and absorption properties of quantum emitters positioned in the hotspots is explicitly discussed. In the end, open challenges are outlined and future possibilities lying ahead are pointed out for this powerful triad of biotechnology, nanooptics, and photophysics. © 2021 The Authors. Advanced Optical Materials published by Wiley-VCH GmbH
- ItemHybrid Optical Fibers – An Innovative Platform for In‐Fiber Photonic Devices(Weinheim : Wiley-VCH, 2015) Alexander Schmidt, Markus; Argyros, Alexander; Sorin, FabienThe field of hybrid optical fibers is one of the most active research areas in current fiber optics and has the vision of integrating sophisticated materials inside fibers, which are not traditionally used in fiber optics. Novel in-fiber devices with unique properties have been developed, opening up new directions for fiber optics in fields of critical interest in modern research, such as biophotonics, environmental science, optoelectronics, metamaterials, remote sensing, medicine, or quantum optics. Here the recent progress in the field of hybrid optical fibers is reviewed from an application perspective, focusing on fiber-integrated devices enabled by including novel materials inside polymer and glass fibers. The topics discussed range from nanowire-based plasmonics and hyperlenses, to integrated semiconductor devices such as optoelectronic detectors, and intense light generation unlocked by highly nonlinear hybrid waveguides.
- ItemPhotodoping and Fast Charge Extraction in Ionic Carbon Nitride Photoanodes(Weinheim : Wiley-VCH, 2021) Adler, Christiane; Selim, Shababa; Krivtsov, Igor; Li, Chunyu; Mitoraj, Dariusz; Dietzek, Benjamin; Durrant, James R.; Beranek, RadimIonic carbon nitrides based on poly(heptazine imides) (PHI) represent a vigorously studied class of materials with possible applications in photocatalysis and energy storage. Herein, for the first time, the photogenerated charge dynamics in highly stable and binder-free PHI photoanodes using in operando transient photocurrents and spectroelectrochemical photoinduced absorption measurements is studied. It is discovered that light-induced accumulation of long-lived trapped electrons within the PHI film leads to effective photodoping of the PHI film, resulting in a significant improvement of photocurrent response due to more efficient electron transport. While photodoping is previously reported for various semiconductors, it has not been shown before for carbon nitride materials. Furthermore, it is found that the extraction kinetics of untrapped electrons are remarkably fast in these PHI photoanodes, with electron extraction times (ms) comparable to those measured for commonly employed metal oxide semiconductors. These results shed light on the excellent performance of PHI photoanodes in alcohol photoreforming, including very negative photocurrent onset, outstanding fill factor, and the possibility to operate under zero-bias conditions. More generally, the here reported photodoping effect and fast electron extraction in PHI photoanodes establish a strong rationale for the use of PHI films in various applications, such as bias-free photoelectrochemistry or photobatteries. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH