is considered a candidate for use as adsorbent materials in sorption-based heat exchangers because of its superior water uptake and high hydrothermal stability. Understanding the sorption−desorption behavior of water in MIL-101(Cr) is required for its real industrial applications. However, the sorption−desorption mechanism of water in MIL-101(Cr) cannot be revealed from the employed standard characterizations involving sorption−desorption isotherms. Here, we report a combined investigation of infrared molecular adsorption and molecular dynamics simulation to analyze the phase transitions of water confined in MIL-101(Cr). The water molecules at a low pressure preferentially coordinate with the metal sites and form one-dimensional water chains from the unsaturated Cr 3+ . As the pressure increases, the water chains grow in length and connect, gradually forming a water monolayer on the inner surface of the MIL cages. This monolayer changes the cage surface property from hydrophobic to hydrophilic, which induces the beginning of water condensation in the 29 and 34 Å cages. The entire pores are filled with condensed water as the experimental pressure gradually reaches 1 atm. A reverse behavior of water is observed as the pressure decreases, and this systematic analysis of water in MIL-101(Cr) suggests the further development of superior materials of sorption-based heat exchangers.

Silicon solar cells among different types of solar energy harvesters have entered the commercial market owing to their high power conversion efficiency and stability. By replacing the electrode and the p‐type layer by a single layer of carbon nanotubes, the device can be further simplified. This greatly augments the attractiveness of silicon solar cells in the light of raw material shortages and the solar payback period, as well as lowering the fabrication costs. However, carbon nanotube‐based silicon solar cells still lack device efficiency and stability. These can be improved by chemical doping, antireflection coating, and encapsulation. In this work, the multifunctional effects of p‐doping, antireflection, and encapsulation are observed simultaneously, by applying a polymeric acid. This method increases the power conversion efficiency of single‐walled carbon nanotube‐based silicon solar cells from 9.5% to 14.4% and leads to unprecedented device stability of more than 120 d under severe conditions. In addition, the polymeric acid‐applied carbon nanotube‐based silicon solar cells show excellent chemical and mechanical robustness. The obtained stable efficiency stands the highest among the reported carbon nanotube‐based silicon solar cells.

A hybrid structure that supports the coupling of a cavity mode and a Tamm plasmon (TP) mode is demonstrated as a spectrally selective thermal emitter for the mid-infrared spectral range. Unlike conventional TP structures, the presented hybrid structure contains an optical cavity sandwiched between the distributed Bragg reflector (DBR) and the metallic mirror of a typical TP structure. In simulation, the TP-cavity hybrid structure exhibits a strong peak (absorptance = 0.993) in the absorption spectrum with a high quality factor (Q = 135), and this absorptance peak can exist over a wide range of resonance wavelengths by adjusting the cavity thickness. Moreover, the hybrid structure shows a small polarization dependence (for incident angles less than 30°, the resonance wavelength of TM and TE differ by less than 2 nm) and a shift of less than 20 nm in the absorptance peak wavelength for incident angles between 0° and 8°. The absorptance peak of the hybrid structure is stronger and sharper than that of a pure TP structure made from the same materials, which has a maximum absorptance of 0.898 and Q-factor of 28, and a Fabry–Perot cavity structure topped with a 5 nm Au layer, which has a maximum absorptance of 0.899 and Q-factor of 25. Upon heating, a strong and narrow bandwidth thermal emittance peak is observed with a maximum emittance value of 0.90 and a Q-factor of 88 at a wavelength of 4.731 μm. This easy-to-fabricate and high-performance infrared thermal emitter is ideal for applications where narrowband infrared light sources are required.

Spectral selective thermal emitters are promising technological components due to their efficiency, large range of available emission wavelengths, simplicity, and long lifetime. Despite intensive effort into narrowband thermal emitters using surface plasmon polaritons, surface phonon polaritons, and Tamm plasmons, material losses have limited the potential quality factors, with the highest reported value being 200. Here, by combining a metallic mirror and an optical Tamm state structure, we propose a hybrid structure that realizes narrowband and wavelength-tunable thermal emission. In the proposed structure, large energy can be stored between the loss-less DBRs (SiO 2 /Ge) thus drastically reducing metal losses. The metallic mirror is set at the bottom of the proposed structure to reduce the transmission losses and guarantee a large absorption/emission. This metal-optical Tamm state structure achieves experimentally a thermal emittance peak with a quality factor of over 750 at a wavelength of around 4.5 m. Moreover, taking advantage of the temperature sensitivity of Ge, the thermal emission wavelength can be tuned by adjusting the operating temperature between 100 and 150 C. Both the high-quality factor and the wavelengthtunable properties demonstrate its suitability as a practical narrowband light source.

Plasmon resonances on 2D nanosquare arrays and their temperature‐dependent modulations are demonstrated using the insulator‐to‐metal transition (IMT) of VO2. A comparison between observed experimental trends and electromagnetic simulations reveals that the plasmon coupling is effective in the periodic 2D alignment of metallic VO2 nanosquares and results in a collective plasmon excitation. This plasmon excitation affects the optical responses of VO2 nanosquares in the mid‐infrared (IR) range through reduction of plasmon damping in relation to the specific band structure of VO2. This preliminary understanding is important for the elucidation of temperature‐dependent plasmon resonances. The IMT of VO2 produces temperature‐dependent plasmon resonances with respect to spectral features. The electrodynamic simulations reveal that these phenomena are based on plasmon coupling in the nanosquare array when each nanosquare acts as a single metallic domain. The hysteretic plasmon resonances are derived from resonant coupling between metallic VO2 nanosquares via the IMT nature of VO2, which results in temperature‐dependent changes in collective plasmon excitations in the nanosquare array.