Focusing on photo-physical processes in organic aggregates, our group has developed the approaches for constructing the effective model Hamiltonian for describing the aggregates and simulating the coupled exciton-vibrational dynamics. The fragment particle and hole densities (FPHD) method has been proposed to obtain the energies and electronic couplings among quasi-diabatic states from the properties of adiabatic excited states. Based on the model Hamiltonian, non-Markovian stochastic Schrödinger equations have been developed to describe photo-physical processes for the systems with multiple electronic states. These approaches can be straightforwardly adopted to calculate vibrationally-resolved absorption spectra for complex systems. Indeed, we used those approaches to investigate the absorption spectra in Zinc Phthalocyanine aggregates. With available approaches, we theoretically investigate the vibrationally resolved absorption spectra and exciton dynamics processes of two kinds of DPND aggregates here. In the work, we discuss in detail the influence of the alkyl side chain in electronic-state properties and explain the origin of different spectral characteristics for two DPND aggregates. Furthermore, we also show the dynamics behaviors of two DPND thin films in the low-energy and high-energy region. The paper is arranged as follows: Sec. II outlines the theoretical methods and presents calculations details, Sec. III is the results and discussion and Sec. IV is the conclusions.