Exploring the properties of 2D phthalocyanine molecular crystals using density functional theory

2D layers of organic molecules and heterostructures of such molecules exhibit a wide variety of properties. These properties can be tuned by modifying the molecules, or changing the stacking configuration. To study and predict the properties of such 2D molecular crystals, and heterostructures made of them, we use density functional theory. We focus on the phthalocyanines (Pc), consisting of 4 isoindole units linked by a ring of nitrogen atoms, that can enclose a central metal ion. These molecules can be deposited in 2D sheets. One avenue of tuning the properties is in modifying that central atom. Another method is by fluorinating the molecules. For example, the latter can be used to modify the position of the band edges of ZnPc. More tunability can be achieved by constructing heterostructures of different molecular crystals, or by combining molecular crystals with inorganic 2D materials. As an example of such a heterostructure, we will discuss the case of heterostructures consisting of F₈ZnPc on ReS₂, focusing on charge transfer between the layers, and comparing with ultrafast transient absorption measurements [1].

[1] P. Valencia-Acuna et al., Appl. Phys. Lett. 118, 153104 (2021).