First-principles calculations are performed to study the magnetism mechanism in undoped ZnO and ZnO doped with nonmagnetic elements X (X = Li, Mg, and Al). In undoped ZnO, it is found that the Zn vacancy is spin-polarized with a magnetic moment of 1.54 μB. The ferromagnetic coupling between two Zn vacancies is favorable in energy and a band coupling model is used to explain the magnetic coupling. In ZnO doped with nonmagnetic elements X, the magnetism is also attributed to the presence of Zn vacancies. The introduction of X reduces the formation energy of Zn vacancy and stabilizes it to some extent.

The limited detection of lead iodide (PbI2) to visible light hinders the further development of PbI2 in the field of optoelectronic applications. A photodetector based on PbI2 nanosheet/CdSe nanobelt (PbI2 NS/CdSe NB) is prepared for the first time. This composite structure exhibits broadband spectral photoresponse from ultraviolet (400 nm) to red (730 nm). More importantly, PbI2 NS/CdSe NB can promote the effective separation of electron–hole pairs and improve the photoelectric performance. Compared to single PbI2 NS, the PbI2 NS/CdSe NB photodetector exhibits higher light–dark current ratio (6.778 × 103 A), responsivity (347.57 A W−1), and detectivity (3.625 × 1015 Jones) under 490 nm illumination. A new strategy is provided here to design broadband and high‐performance photodetectors.

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First-principles calculations have been performed to study the magnetic properties of Zn12O12 clusters doped with one or two C atoms at the O site. The results show that one C introduces a total moment of 2 µB, which mainly comes from the spin-polarized C-2p states in the band gap. The ferromagnetic coupling occurs only at the (0, 1) doping configuration, in which the C•••C distance is 5.42 Å, and other doping configurations are nonmagnetic or antiferromagnetic. The ferromagnetism is mediated by holes through the p-d hybridization-like p-p coupling interaction between the C dopants and the neighboring O atoms.