Perovskite/silicon tandem solar cells are promising avenues for achieving high-performance photovoltaics with low costs. However, the highest certified efficiency of perovskite/silicon tandem devices based on economically matured silicon heterojunction technology (SHJ) with fully textured wafer is only 25.2% due to incompatibility between the limitation of fabrication technology which is not compatible with the production-line silicon wafer. Here, a molecular-level nanotechnology is developed by designing NiOx /2PACz ([2-(9H-carbazol-9-yl) ethyl]phosphonic acid) as an ultrathin hybrid hole transport layer (HTL) above indium tin oxide (ITO) recombination junction, to serve as a vital pivot for achieving a conformal deposition of high-quality perovskite layer on top. The NiOx interlayer facilitates a uniform self-assembly of 2PACz molecules onto the fully textured surface, thus avoiding direct contact between ITO and perovskite top-cell for a minimal shunt loss. As a result of such interfacial engineering, the fully textured perovskite/silicon tandem cells obtain a certified efficiency of 28.84% on a 1.2-cm2 masked area, which is the highest performance to date based on the fully textured, production-line compatible SHJ. This work advances commercially promising photovoltaics with high performance and low costs by adopting a meticulously designed HTL/perovskite interface.
Selective electron collection by an interfacial layer modified indium tin oxide cathode is critically important for achieving high-efficiency inverted structure organic photovoltaic (OPV) cells. Here, we demonstrate that solution-processed alkali carbonates, such as Li2CO3, Na2CO3, K2CO3, Rb2CO3, Cs2CO3, are good interfacial layer materials. Both carbonate concentration and annealing conditions can affect cathode work function and surface roughness. By proper optimization, different alkali carbonates can be almost equally effective as the cathode interfacial layer. Furthermore, good device performance can be achieved at a low annealing temperature (<50 ° C), which allows for potential applications in solution-processed inverted OPV cells on plastic substrates. This work indicates that alkali carbonates, not just cesium carbonate, are valid choices as the cathode interlayer in inverted OPV devices.
Colorful flexible polymer tandem organic solar cells have been demonstrated using a transparent conducting polymer PEDOT:PSS as the top electrode as well as an optical engineering layer.
Amorphous polymer grafted MWNTs were synthesized by free radical copolymerization of styrene and MWNTs with vinyl groups. The AP-g-CNT samples were found to be soluble in a variety of organic solvents, such as DMF, CH 2 Cl 2 , and other common organic solvents for polystyrene. AP-g-CNT exhibit novel lyotropic and thermotropic liquid crystallinity with pattern-like crack texture in solution and molten states, respectively. The CNTs could be linked to the amorphous polymer by covalent bonds to form some novel assembly patterns including vertically aligned columns, micro-sized mono-layered and multi-layered holes. The results pave a new method for developments of novel nano-electronic devices.
Bacterial-associated wound infection and antibiotic resistance have posed a major burden on patients and health care systems. Thus, developing a novel multifunctional antibiotic-free wound dressing that cannot only effectively prevent wound infection, but also facilitate wound healing is urgently desired. Herein, a series of multifunctional nanocomposite hydrogels with remarkable antibacterial, antioxidant, and anti-inflammatory capabilities, based on bacterial cellulose (BC), gelatin (Gel), and selenium nanoparticles (SeNPs), are constructed for wound healing application. The BC/Gel/SeNPs nanocomposite hydrogels exhibit excellent mechanical properties, good swelling ability, flexibility and biodegradability, and favorable biocompatibility, as well as slow and sustainable release profiles of SeNPs. The decoration of SeNPs endows the hydrogels with superior antioxidant and anti-inflammatory capability, and outstanding antibacterial activity against both common bacteria (E. coli and S. aureus) and their multidrug-resistant counterparts. Furthermore, the BC/Gel/SeNPs hydrogels show an excellent skin wound healing performance in a rat full-thickness defect model, as evidenced by the significantly reduced inflammation, and the notably enhanced wound closure, granulation tissue formation, collagen deposition, angiogenesis, and fibroblast activation and differentiation. This study suggests that the developed multifunctional BC/Gel/SeNPs nanocomposite hydrogel holds a great promise as a wound dressing for preventing wound infection and accelerating skin regeneration in clinic.
Dual-wavelength mode-locked lasers can be widely used in optical communication, pump-probe experiment, nonlinear frequency conversion, etc. In this paper, a dual-wavelength self-mode-locked semiconductor disk laser is reported for the first time, to the best of our knowledge. A simple linear resonator is formed by using a high reflectivity distributed Bragg reflector at the bottom of the gain chip, and an external output mirror; the cavity length is about 135 mm, with no need of additional inserted elements. Based on the Kerr effect of the gain medium and the soft aperture formed by the pump spot on the gain chip, along with the fine adjustment of cavity length and pump intensity, the mode-locking process can be started from the free running and the stable self-mode-locking can be realized. The mode-locked pulse width is 4.3 ps, the repetition rate is 1.1 GHz, and the maximum output power is 323.9 mW, which corresponds to a peak power of 68 W. After the laser is mode locked, a readily available blade, which can introduce a wavelength-dependent loss for different laser modes, resulting in a lager cavity loss for a longer-wavelength mode and a smaller cavity loss for a shorter-wavelength mode, is used as a wavelength tuning element, and is inserted into the cavity in the direction perpendicular to the optical axis of the resonator. By changing the depth of the blade inserted into the cavity, the laser wavelength can be continuously tuned from the initial oscillating wavelength (longer-wavelength) to a shorter wavelength, a stable dual-wavelength output with equal intensity can be obtained at a specific position, and the stable continuous-wave mode-locking can be maintained simultaneously. The steady dual-wavelengths in the experiment are 951 and 961 nm, and the corresponding output power is 32 mW. The above dual-wavelength outputs have good coherence since they are stimulated radiations from the same gain chip. Meanwhile, they have relatively high peak power and strictly meet the coaxial conditions, and these are all advantages for the difference frequency generation (DFG). The frequency of the DFG in the experiment is approximately 3.3 THz, which can be widely used in laser radar, remote sensing, homeland security, counter-terrorism, atmospheric and environmental monitoring and otherareas.
A tactile sensor is an essential component for realizing biomimetic robots, while the flexibility of the tactile sensor is a pivotal feature for its application, especially for electronic skin. In this work, a flexible self-powered tactile sensor array was designed based on the piezoelectricity of ZnO nanorods (NRs). The field-limited ordered ZnO NRs were synthesized on a flexible Kapton substrate to serve as the functional layer of the tactile sensor. The electrical output performances of the as-fabricated tactile sensor were measured under pressing and bending forces. Moreover, we measured the human-finger pressure detection performance of the tactile sensor array, suggesting that the corresponding mapping figure of finger pressure could be displayed on the monitor of a personal computer (PC) in the form of lighted LED and color density through a LabVIEW system. This as-grown sensory feedback system should be of potential valuable assistance for the users of hand prostheses to reduce the risk and obtain a greater feeling of using the prostheses.
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