Two-dimensional organic-inorganic molecular cocrystal.

Molecular cocrystal engineering has emerged as an efficient approach to achieving multiple functionalities and novel applications in photonics and optoelectronics. However, the reported two-dimensional (2D) molecular cocrystals are predominantly composed of organic molecules, whereas the preparation of organic-inorganic molecular cocrystals (OIMCs) still remains challenging. Here, we achieved the self-assembly of the 2D OIMC C60·2P4S3 for the first time, which has a stable layered packing arrangement, driven by π-π interactions and C-P contacts between these two cage molecules. We found that the strong C-P contacts suppress non-radiative transitions and enhance vibrational coupling, resulting in an efficient emission with a quantum yield of 13.24%. Unlike the molecular units of C60 and P4S3, the cocrystal demonstrates asymmetric optical waveguides with a high anisotropic ratio of 3.625, which can be attributed to the anisotropy of vibrational transition. This work can provide new light on the design of molecular cocrystals and promote the development of molecular physics and optoelectronics.