An amphiphilic electron-deficient (n-type) perylene diimide has been synthesized and characterized. The diimide contains a hydrophobic long chain on one end and a hydrophilic ethoxy chain on the other. The self-assembly of this molecule in polar and nonpolar. solvents has been demonstrated by concentration- and temperature-dependent absorption and fluorescence spectroscopies. Analysis of the spectral change for the aggregates shows typical J-aggregates for structures precipitated from polar solvents and H-aggregates for structures precipitated from nonpolar solvents. SEM and TEM micrographs and a suggested packing scheme, compatible with the formation of nanostrips in nonpolar solvents, and nanofibers in polar solvents, are presented.