Toroidal excitation manifests as currents flowing on the surface of a torus along its meridians that are known as poloidal currents. Several intriguing phenomena such as nonradiating anapole excitation, dynamic Aharonov–Bohm effect, and vector potential in the absence of electromagnetic fields occur in the presence of toroidal excitations. Toroidal resonances in metamaterials also offer a platform to probe strong light–matter interactions in its proximity due to the nonradiating confinement of photons. Here, a dual‐torus toroidal flexible metasurface containing an array of overlapped split ring resonators is experimentally demonstrated, which results in strong field confinement for enhanced sensing of polar liquid analytes. Microfluidic integrated dual‐torus toroidal resonance experimentally shows significantly higher sensitivity of 124.3 GHz per refractive index unit compared to a single torus toroidal resonance. Flexible metasurfaces supporting dual torus toroidal resonance can find a wide range of applications in the development of ultrasensitive terahertz molecular sensors for probing real time monitoring of chemicals and biomolecules.

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Perovskite solar cells (PSCs) employing organic-inorganic halide perovskite as active layers have attracted the interesting of many scientists since 2009. The power conversion efficiency (PCE) have pushed certified 25.2% in 2019 from initial 3.81% in 2009, which is much faster than that of any type of solar cell. In the process of optimization, many innovative approaches to improve the morphology of perovskite films were developed, aiming at elevate the power conversion efficiency of perovskite solar cells (PSCs) as well as long-term stability. In the context of PSCs research, the perovskite precursor solutions modified with different additives have been extensively studied, with remarkable progress in improving the whole performance. In this comprehensive review, we focus on the forces induced by additives between the cations and anions of perovskite precursor, such as hydrogen bonds, coordination or some by-product (e.g., mesophase), which will lead to form intermediate adduct phases and then can be converted into high quality films. A compact uniform perovskite films can not only upgrade the power conversion efficiency (PCE) of devices but also improve the stability of PSCs under ambient conditions. Therefore, strategies for the implementation of additives engineering in perovskites precursor solution will be critical for the future development of PSCs. How to manipulate the weak forces in the fabrication of perovskite film could help to further develop high-efficiency solar cells with long-term stability and enable the potential of future practical applications.

Highly uniform polyurea microspheres are prepared with tunable crosslinking through precipitation polymerization of IPDI with diethylenetriamine (DETA) in water–acetone binary solvent.

The continuous wave (CW) and passively Qswitched Nd:Gd3AlxGa5−xO12 (Nd:GAGG) laser operation at 938 nm have been realized for the first time. The maximum CW output power of 0.44 W was obtained under the absorbed pump power of 8.54 W, corresponding to the slope efficiency of 7.8% and optical-to-optical efficiency of 5.2% respectively. A V 3+ :YAG saturable absorber crystal with the initial transmission of 97% was used for the passive Q-switching regime. The maximum average output power of 0.19 W was achieved with the minimum pulse width of 358 ns and Q-switched repetition rate of 116 kHz. The corresponding single pulse energy and pulse peak power were determined to be 1.6 μJ and 4.6 W, respectively.