Yangyang Wang

Despite their exceptional optoelectronic properties, organic‐inorganic halide perovskites have a fatal flaw of weak moisture instability. Here, we demonstrate that MAPbI ₃ single crystals exhibit a unique combination of hierarchical defense to water and self‐healing capability, with their skeleton structure nearly unaffected by water. The crystals maintain structural integrity for over one month while floating on water and show a reversible black‐to‐yellow‐to‐black phase transition. Surface hydration reverses by natural drying, while bulk hydration can be completely recovered by solvent immersion. The surface microstructure enhanced hydrophobicity and the inherently water‐resistant (110) facet play key roles in blocking water ingress. Even upon water invasion, the crystal forms a hydrate that preserves the critical [PbI ₆ ] ⁴⁻ octahedral framework, providing the structural basis for subsequent dehydration and self‐healing. The devices with the self‐healed crystal have 98% efficiency of the devices with the original crystal, and they maintain 90% efficiency after 1300 and 2000 h in air, respectively. This work demonstrates the exceptional water tolerance of perovskite single crystals, promising long‐term stable optoelectronic devices.

A novel terahertz polarization isolator using a two-dimensional square lattice tellurium rod array is numerically investigated at the interesting band of 0.22 THz in this short paper. The isolator is designed by inserting six hexagonal tellurium rods into a fully polarized photonic crystals waveguide with high efficiency of −0.34 dB. The TE and TM photonic band gaps of the 7 × 16 tellurium photonic crystals are computed based on the plane wave expansion method, which happen to coincide at the normalized frequency domain from 0.3859(a/λ) to 0.4033(a/λ), corresponding to the frequency domain from 0.2152 to 0.2249 THz. The operating bandwidth of the tellurium photonic crystals waveguide covers 0.2146 to 0.2247 THz, calculated by the finite element method. The six hexagonal tellurium rods with smaller circumradii of 0.16a serve to isolate transverse electric waves and turn a blind eye to transverse magnetic waves. The polarization isolation function and external characteristic curves of the envisaged structure are numerically simulated, which achieves the highest isolation of −33.49 dB at the central frequency of 0.2104 THz and the maximum reflection efficiency of 98.95 percent at the frequency of 0.2141 THz. The designed isolator with a unique function and high performance provides a promising approach for implementing fully polarized THz devices for future 6G communication systems.

Interface engineering is very important to the high performance of organic optoelectronic devices that are commonly composed of multi-layer thin solid films. Interfacial materials are particularly crucial for interface engineering, and a variety of materials have been employed at the interface to accomplish various different functions. This review summarizes various materials for the interfaces and some of the latest progress in organic solar cells (OSCs) and organic photodetectors (OPDs).

Laminated multilayers of perovskite films with different optical and electronic characteristics will easily realize high‐performance optoelectronic devices because it is widely demonstrated that differential distribution of film properties in the vertical direction of devices plays particularly important roles in device performance. However, the existing laminated perovskite films are hardly prepared by a solution process because there is no solvent with sufficient selectivity of solubility for different perovskite materials. Here, it is demonstrated that aniline (AN) has a largely different solubility toward the perovskite MAPbI₃ and the MAPbI₃ blend with an additive of hydrochloride diethylammonium chloride. By using AN as the solvent in the perovskite precursor solution, two laminated perovskite layers with different crystal size and optical and electrical characteristics are achieved. Inverted perovskite solar cells with the laminated films as active layers achieve an averaged power conversion efficiency of 20.65% originating from the high V_OC 1.112 V and fill factor of 80.8%. The devices maintain 98% efficiency after 400 h under 65% RH. This work provides a very simple and feasible method for production of laminated perovskite films to achieve high‐performance perovskite solar cells.

A novel convenient and efficient approach to produce CsSnI₃ QDs through a one-pot synthesis is employed to largely enhance the PCE of lead-free perovskite solar cells (PVSCs). The CsSnI₃ QD-based device has the maximum PCE of 5.03%, which is the highest performance for all-inorganic lead-free PVSCs reported so far.