We report a new approach for large-scale alignment of micron-sized J-aggregates of a derivative of porphyrin onto planar glass substrates. We applied a unidirectional nitrogen flow to an aqueous dye drop deposited onto a glass substrate to form an about 5 nm thick film of aligned J-aggregates over macroscopic surface areas up to several millimeters. The inter-aggregate distance is ∼500 nm, and it scales with the nitrogen pressure. We verified the film thickness and J-aggregate alignment using multimodal microscopy and spectroscopy techniques. Our technique is fast, simple, and cost-effective for producing large two-dimensional (2-D) arrays of aligned emitters.