This review describes the photodriven energy-and electron-transfer processes of the columnar perylenediimide (PDI) nanostructures for efficient light-energy conversion by employing the self-assembly models. The charge separation and the directional charge transport of the oligomers, aggregates, and one-dimensional (1D) nanostructures of PDIs have been clarified by using time-resolved transient absorption techniques. Excited states, exciton migration, and excitation energy-transfer processes were examined in the first part. The second part involves the electron hopping, photodriven electron transfer and transport events taking place within the various PDI nanostructures.Unique light-harvesting and redox properties together with high chemical, thermal and photostability make perylenediimides (PDIs) the essential building blocks of energy and electron donor-acceptor systems. One important feature of PDI is its large π-plane enabling the π-π interactions for self-assembly. 1 PDIs can form one-dimensional (1D) nanostructures by supramolecular self-assembly in the solution as a low-cost, affordable bottom-up method. 2-4 The length of PDI nanofibrils can reach about 0.3 mm due to strong π-stacking in 'poor' solvents. 5 Other than the solvophobic effects, 6-8 hydrogen bonding 9-12 and ionic interactions 13-15 assisting π-π interactions have been used to fabricate nanoscale materials of PDIs in one dimension. Coupled crystallization of PDI with proper polymer templates by solvent evaporation 16 and chemical-reaction mediated self-assembly in the solution 17,18 are the other convenient bottom-up methods for the fabrication of 1D nanofibers of PDI. The long axes of these 1D structures are feasible for long-range exciton diffusion when exposed to light 19,20 and for electron transport after an electron-transfer process from electron donors. 21,22 Such features of 1D nanostructures of PDI have led to various applications. For example, n-type semiconducting properties of PDI nanowires have been utilized in organic field effect transistors 23-25 and phototransistors. 26 Nanostructures of PDIs have also been widely used in the sensing applications for nitrobased explosives, 27 organic amines, 28 and nitrogen-based reducing agents. 29,30 Their photovoltaic properties have been also reported. 31,32 There have been many comprehensive reviews regarding the fabrication methods and the applications of 1D nanostructures of PDIs together with various organic materials, some of which are already referred in this review. [2][3][4]11 Besides these aspects, elucidation of the fundamental energy and electron-transfer events taking place within the PDI nanostructures is also of importance to improve the quality and efficiency of the current applications and to rationalize the future design of the related devices. This review will basically focus on the photoinduced energy-and electron-transfer processes occurring in the aggregates and nanostructures of PDIs, which mainly have 1D geometry. Photoinduced processes of supramolecular oligomeric an...