Ternary layered materials with small band gaps are prospective candidates for future UV–Vis–NIR broadband photodetectors, which show multiple degrees of freedom for tailoring their optoelectrical properties. AgIn5Se8 (AIS), with a direct bandgap (around 1.25 eV) and n-type conductivity, has great application potential in UV–Vis–NIR broadband optoelectronics due to its excellent light stability and high optical conductivity. However, research on AIS-based self-powered photodetectors with a broad spectrum and fast response speed is still rare. In this work, we report a self-powered photodetector based on a AgIn5Se8/FePSe3 (FPS) n–p heterojunction with a spectral detection range of 365–1020 nm. Benefiting from the built-in field, the type II heterojunction can suppress dark current and promote the rapid separation of electron–hole pairs. As a result, the fabricated photodetector exhibits a low dark current of 1 pA and a fast response time (τr/τd) of less than 20/20 ms. The results indicate that an AIS/FPS heterojunction proves to be an excellent candidate for broad spectrum, fast response, and self-powered photoelectronic devices.

Organic charge-transfer cocrystals (CTCs) have attracted significant research attention due to their wide range of potential applications in organic optoelectronic devices, organic magnetic devices, organic energy devices, pharmaceutical industry, etc. The physical properties of organic charge transfer cocrystals can be tuned not only by changing the donor and acceptor molecules, but also by varying the stoichiometry between the donor and the acceptor. However, the importance of the stoichiometry on tuning the properties of CTCs has still been underestimated. In this review, single-crystal growth methods of organic CTCs with different stoichiometries are first introduced, and their physical properties, including the degree of charge transfer, electrical conductivity, and field-effect mobility, are then discussed. Finally, a perspective of this research direction is provided to give the readers a general understanding of the concept.

Weak intermolecular interactions, such as π-π interactions, hydrogen bonds, halogen bonds and charge transfer interactions, are important to tuning the physical properties of organic charge transfer cocrystals. However, it is...