In this work, photoluminescence (PL), admittance spectroscopy (AS) and drive-level capacitance profiling (DLCP) were performed to analyze the defect properties of a Cu₂ZnSnS₄ (CZTS) solar cell. Compared to a high efficiency CuInGaSe₂ (CIGS) solar cell, the absorber of the CTZS device has larger potential fluctuation which can be attributed to the co-existence of a high concentration of deep acceptor (Cu_Zn) and deep donor (Zn_Cu) defects. The density of the interface states in the CZTS device is also orders higher than that in the CIGS device. These high density defects (both in the bulk and at the CZTS/CdS interface) will induce a large loss in the open-circuit voltage (V_oc), resulting in a lower performance of the CZTS device. We suggest that defect control can be a possible solution to reduce the potential fluctuation induced by acceptors. To overcome the potential fluctuation induced trapping effect for electrons by the Zn_Cu donors, a graded conduction band similar to CIGS will be good to eliminate electron localization.

Thin, lightweight, and flexible textile pressure sensors with the ability to detect the full range of faint pressure (<100 Pa), low pressure (≈KPa) and high pressure (≈MPa) are in significant demand to meet the requirements for applications in daily activities and more meaningfully in some harsh environments, such as high temperature and high pressure. However, it is still a significant challenge to fulfill these requirements simultaneously in a single pressure sensor. Herein, a high‐performance pressure sensor enabled by polyimide fiber fabric with functionalized carbon‐nanotube (PI/FCNT) is obtained via a facile electrophoretic deposition (EPD) approach. High‐density FCNT is evenly wrapped and chemically bonded to the fiber surface during the EPD process, forming a conductive hierarchical fiber/FCNT matrix. Benefiting from the large compressible region of PI fiber fabric, abundant yet firm contacting points and high elastic modulus of both PI and CNT, the proposed pressure sensor can be customized and modulated to achieve both an ultra‐broad sensing range, long‐term stability and high‐temperature resistance. Thanks to these merits, the proposed pressure sensor could monitor the human physiological information, detect tiny and extremely high pressure, can be integrated into an intelligent mechanical hand to detect the contact force under high‐temperature.

We demonstrate tunable 3D light trapping (up to ∼96%) architectures based on the SnSe₂nanoplate arrays (NPAs)viaself-assembled growth and high performance (EF: 6.33 × 10⁶, LOD: 1 × 10⁻¹²M) SERS substrates based on SnSe₂NPAs.

High pressure structure, stability, metallization and superconductivity of PbH₄(H₂)₂, a H₂-containing compound combining one of the heaviest elements with the lightest element, are investigated by the first-principles calculations. The metallic character is found over the whole studied pressure range, although PbH₄(H₂)₂ is metastable and easily decompose at low pressure. The decomposition pressure point of 133 GPa is predicted above which PbH₄(H₂)₂ is stable both thermodynamically and dynamically with the C2/m symmetry. Interestedly, all hydrogen atoms pairwise couple into H₂ quasi-molecules and remain this style up to 400 GPa in the C2/m structure. At high-pressure, PbH₄(H₂)₂ tends to form the Pb-H₂ alloy. The superconductivity of T_c firstly rising and then falling is observed in the C2/m PbH₄(H₂)₂. The maximum of T_c is about 107 K at 230 GPa. The softening of intermediate-frequency phonon induced by more inserted H₂ molecules is the main origin of the high T_c. The results obtained represent a significant step toward the understanding of the high pressure behavior of metallic hydrogen and hydrogen-rich materials, which is helpful for obtaining the higher T_c.