A self-assembling plasmonic absorber absorbs light efficiently across a wide range of wavelengths and could be used in nanophotonic devices.

Recent advances in molecular organic photovoltaics (OPVs) have shown 10% power conversion efficiency (PCE) for single-junction cells, which put them in direct competition with PVs based on amorphous silicon. Incorporation of plasmonic nanostructures for light trapping in these thin-film devices offers an attractive solution to realize higher-efficiency OPVs with PCE>>10%. This article reviews recent progress on plasmonic-enhanced OPV devices using metallic nanoparticles, and one-dimensional (1D) and two-dimensional (2D) patterned periodic nanostructures. We discuss the benefits of using various plasmonic nanostructures for broad-band, polarization-insensitive and angle-independent absorption enhancement, and their integration with one or two electrode(s) of an OPV device.

Radiative cooling is a passive cooling strategy with zero consumption of electricity, and it can be used to radiate heat from buildings to reduce air conditioning requirements. Although this technology can work well during optimal atmospheric conditions at nighttime, it is essential to achieve efficient cooling during daytime when peak cooling demand actually occurs. In this article, we report an inexpensive planar polydimethylsiloxane (PDMS)/metal thermal emitter, i.e., a thin film structure, which was fabricated using a fast solution coating process that is scalable for large area manufacturing. By performing tests under different environmental conditions, temperature reductions of 9.5 °C and 11.0 °C were demonstrated in the laboratory and outdoor environment, respectively, with an average cooling power of ~120 W/m 2 for the thin film thermal emitter. In addition, a spectral-selective structure was designed and implemented to suppress the solar input and control the divergence of the thermal emission beam. This enhanced the directionality of the thermal emissions, so the emitter's cooling performance was less dependent on the surrounding environment. Outdoor experiments were performed in Buffalo NY realizing continuous allday cooling of 2~9 °C on a typical clear sunny day at Northern United States latitudes. This practical strategy that cools without electricity input could have a significant impact on global energy consumption.

Passive solar vapor generation represents a promising and environmentally benign method of water purification/desalination. However, conventional solar steam generation techniques usually rely on costly and cumbersome optical concentration systems and have relatively low efficiency due to bulk heating of the entire liquid volume. Here, an efficient strategy using extremely low‐cost materials, i.e., carbon black (powder), hydrophilic porous paper, and expanded polystyrene foam is reported. Due to the excellent thermal insulation between the surface liquid and the bulk volume of the water and the suppressed radiative and convective losses from the absorber surface to the adjacent heated vapor, a record thermal efficiency of ≈88% is obtained under 1 sun without concentration, corresponding to the evaporation rate of 1.28 kg (m2 h)−1. When scaled up to a 100 cm2 array in a portable solar water still system and placed in an outdoor environment, the freshwater generation rate is 2.4 times of that of a leading commercial product. By simultaneously addressing both the need for high‐efficiency operation as well as production cost limitations, this system can provide an approach for individuals to purify water for personal needs, which is particularly suitable for undeveloped regions with limited/no access to electricity.

Abstract100% efficiency is the ultimate goal for all energy harvesting and conversion applications. However, no energy conversion process is reported to reach this ideal limit before. Here, an example with near perfect energy conversion efficiency in the process of solar vapor generation below room temperature is reported. Remarkably, when the operational temperature of the system is below that of the surroundings (i.e., under low density solar illumination), the total vapor generation rate is higher than the upper limit that can be produced by the input solar energy because of extra energy taken from the warmer environment. Experimental results are provided to validate this intriguing strategy under 1 sun illumination. The best measured rate is ≈2.20 kg m−2 h−1 under 1 sun illumination, well beyond its corresponding upper limit of 1.68 kg m−2 h−1 and is even faster than the one reported by other systems under 2 sun illumination.

We explore a novel mechanism for slowing down THz waves based on metallic grating structures with graded depths, whose dispersion curves and cutoff frequencies are different at different locations. Since the group velocity of spoof surface plasmons at the cutoff frequency is extremely low, THz waves are actually stopped at different positions for different frequencies. The separation between stopped waves can be tuned by changing the grade of the grating depths. This structure offers the advantage of reducing the speed of the light over an ultrawide spectral band, and the ability to operate at various temperatures, but demands a stringent requirement for the temperature stability.

The reported "trapped rainbow" storage of THz light in metamaterials and plasmonic graded structures has opened an attractive new method to control electromagnetic radiation. Here, we show how, by incorporating the frequency-dependent dielectric properties of the metal, the graded grating structures developed for "trapped rainbow" storage of THz light in mum level can be scaled to nm level for telecommunication waves for applications in optical communication and various nanophotonic circuits.

We experimentally demonstrate a plasmonic Mach-Zehnder interferometer (MZI) integrated with a microfluidic chip for ultrasensitive optical biosensing. The MZI is formed by patterning two parallel nanoslits in a thin metal film, and the sensor monitors the phase difference, induced by surface biomolecular adsorptions, between surface plasmon waves propagating on top and bottom surfaces of the metal film. The combination of a nanoplasmonic architecture and sensitive interferometric techniques in this compact sensing platform yields enhanced refractive index sensitivities greater than 3500 nm/RIU and record high sensing figures of merit exceeding 200 in the visible region, greatly surpassing those of previous plasmonic sensors and still hold potential for further improvement through optimization of the device structure. We demonstrate real-time, label-free, quantitative monitoring of streptavidin-biotin specific binding with high signal-to-noise ratio in this simple, ultrasensitive, and miniaturized plasmonic biosensor.