Theoretical Modeling of Exciton Dynamics in Crystalline Phthalocyanine Thin Films

Phthalocyanine (Pc)-based molecular thin films have recently emerged as a promising class of organic semiconductor materials for optoelectronic applications owing to their long exciton coherence length and efficient exciton diffusion. However, the dependence of their excitonic properties on dimensionality, thermodynamic conditions, the presence of metal ions, and chemical modifications to the Pc framework remains not fully understood. As a first step toward a comprehensive theoretical understanding of exciton dynamics in Pc thin films, we have modeled their low-temperature exciton absorption spectra using the Frenkel exciton Hamiltonian. Building upon this framework, we are further probing exciton transport across different dynamical regimes—ranging from incoherent Förster-type hopping to coherent Redfield-like transport—thereby elucidating the crossover between localized and delocalized exciton motion. These investigations aim to provide mechanistic insights into how microscopic interactions and environmental fluctuations govern exciton mobility in Pc thin films.