Using our recently developed non-adiabatic excited-state dynamics simulations framework, we study ultrafast dynamics and exciton transport in several large molecular systems. These simulations reveal a fascinating interplay of conformational vibrational dynamics and internal conversion followed photoexcitation, which has specific spectroscopic signatures and can be observed using time-resolved pump-probe spectroscopies. Observed relationships between spatial extent/properties of electronic wavefunctions and resulting electronic functionalities allow us to understand and to potentially manipulate excited state dynamics and energy transfer pathways in a number of organic molecular materials suitable for a variety of technological applications.