Kesterite Cu2ZnSnS4 is a promising photovoltaic material containing low‐cost, earth‐abundant, and stable semiconductor elements. However, the highest power conversion efficiency of thin‐film solar cells based on Cu2ZnSnS4 is only about 11% due to low open‐circuit voltage and fill factor mainly caused by antisite defects and unfavorable heterojunction interface. In this work, a postannealing procedure is proposed to complete a Cd‐alloyed Cu2ZnSnS4 device. The postannealing to complete the device significantly enhances the performance of the indium tin oxide and promotes the moderate interdiffusion of elements between the layers in the device. As a result of the diffusion of Cu, Zn, In, and Sn, the interfacial electron and hole densities are improved, leading to the achievement of a suitable band alignment for carrier transport. The postannealing also reduces the interface traps and deep‐level defects, contributing to decreased nonradiative recombination. Therefore, the open‐circuit voltage and fill factor are both improved, and an efficiency over 12% for pure sulfide‐based kesterite thin‐film solar cells is obtained.

Electromagnetic (EM) characteristics of superparamagnetic graphite-coated FeNi3 nanocapsules were studied at 2–18 GHz. Compared with FeNi3 nanoparticles coated by an amorphous oxide layer, the natural resonance and attenuation properties of the graphite-coated FeNi3 nanocapsules were dramatically enhanced, due to the coating of the graphite. Graphite layers can restrain the growth of FeNi3 nanocapsules, increase the resistivity, enhance the resonance frequency, keep the real part of permeability almost constant at high frequency and increase the magnetic loss. As a result of enhanced natural resonance and attenuation properties, the FeNi3/C nanocapsules exhibit good EM absorption properties.

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