Designing and manufacturing cost-effective absorbers that can cover the full-spectrum of solar irradiation is still critically important for solar harvesting. Utilizing control of the lightwave reflection and transmission, metamaterials realize high absorption over a relatively wide bandwidth. Here, a truncated circular cone metasurface (TCCM) composed of alternating multiple layers of titanium (Ti) and silicon dioxide (SiO2) is presented. Enabled by the synergetic of surface plasmon resonances and Fabry–Pérot resonances, the TCCM simultaneously achieves high absorptivity (exceed 90%), and absorption broadband covers almost the entire solar irradiation spectrum. In addition, the novel absorber exhibits great photo-thermal property. By exploiting the ultrahigh melting point of Ti and SiO2, high-efficiency solar irradiation absorption and heat release have been achieved at 700 °C when the solar concentration ratio is 500 (i.e., incident light intensity at 5 × 105 W/m2). It is worth noting that the photo-thermal efficiency is almost unchanged when the incident angle increases from 0° to 45°. The outstanding capacity for solar harvesting and light-to-heat reported in this paper suggests that TCCM has great potential in photothermal therapies, solar desalination, and radiative cooling, etc.
Defects located in the surface of quantum dots highly impact carrier dynamics and transfer, which would limit the photoelectric conversion efficiency (PCE) of perovskite quantum dot solar cells. Herein, we deposit high-quality FAPbBr 3 quantum dot films through passivating Pb salts and conducting damage-free drying processes. The results indicate that the process of PbBr 2 treatment and vacuum drying process fill both the Pb 2+ and Br − vacancies and minimize the damage of the FAPbBr 3 quantum dot film. The device assembled with this film achieved a champion PCE of 3.11% and involved an ultrahigh open-circuit voltage of 1.67 V or more. In addition, both the corresponding FAPbBr 3 quantum dot films and devices exhibited higher humidity stability than the control films and devices. These studies will provide insights for designing high-quality perovskite quantum dot films with superior optoelectronic properties.
Despite the fact that solar energy has been widely used as a renewable and clean energy source for decades, when designing solar irradiation absorbers one is generally confronted with the dilemma of choosing between higher absorption but narrowband or broadband but lower absorption, which has greatly limited the development of the solar energy industry. In this work, a gradient cavity-thin-film metasurface (GCM) made up of alternating multiple layers of titanium (Ti) and silicon dioxide (SiO2) exhibits ultra-broadband strong absorption in 354–2980 nm. The operating bandwidth covers the dominating portion of the solar irradiation spectrum. The absorption spectrum can be manipulated by adjusting the structural parameters of the unit cell. It is worth noting that the spectrally weighted solar absorption efficiency reaches 98.28% under the AM 1.5G illumination. This impressive near-unity absorption could be attributed to multiple light–matter interactions including surface plasmon resonances, cavity resonance, and the intrinsic spectral responses of multi-layer refractory material. In addition, the absorption response is insensitive to the incident angle and polarization states. These high performances provide the GCM with great potential for practical applications in solar thermal energy harvesting and photothermal conversion, etc.
With the development of wireless sensor networks, many building energy management systems are getting to adopt wireless sensor network as their communication infrastructure. However, the existing wireless sensor network protocols cannot satisfy the energy-saving demand of building energy management systems. Considering the characteristics of the building energy management system wireless sensor networks, a novel energy-efficient routing scheme is proposed called relay participated-new-type building energy management system. Nodes in the building energy management system wireless sensor networks are divided into two types: energy-limited nodes (battery powered) and energy-unlimited nodes (main powered, solar charger, or heat energy powered). Relay participated-new-type building energy management system allows energy-unlimited nodes to temporarily receive packets that are routed to a nearby energy-limited nodes. In this way, time synchronization for low-power sleep at media access control layer is no longer required, which reduces the delay and control overhead at media access control layer dramatically. Relay participated-new-type building energy management system reduces energy usage of energy-limited nodes and extend the lifetime of wireless sensor networks in new-type building energy management systems. Simulation results show that the relay participated-new-type building energy management system protocol significantly improves energy efficiency of limited energy nodes and reduces latency as compared to ad hoc on-demand distance vector-sensor medium access control and low-energy adaptive clustering hierarchy.
:Narrowband light absorber with multi-band plasmonic resonances is numerically investigated for high-performance electrical manipulation via introducing the electro-optic (EO) medium in the slit array based grating structure. A maximal absorption efficiency of 99.5% is achieved. The spectral shift sensitivity reaches 0.99 nm/V. Besides, the large spectral intensity change is also obtained due to the use of sharp resonances, which therefore ensures the high signal-to-noise ratio for the manipulation process. It is observed that the strong surface plasmon resonance and the localized optical cavity modes can introduce the differential responses for the multiple modes under the optical adjusting process and also for the EO manipulation process. These features not only contribute to produce the new EO modulator platforms based on the light absorbers but also pave new ways for the cavity-enhanced high-performance EO operation. Moreover, the absorption properties can be well maintained in a wide range of the structural parameters, indicating the high tolerance of the fabrication process. The findings can pave new insights into the high-performance manipulations via the narrowband absorbers with strong electromagnetic field enhancement and hold wide applications in dynamic switching, filtering, displaying, etc.
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