We present the first detailed structure-function study of a photoconducting ionic porphyrin supermolecular assembly, fabricated from tetra(N-methyl-4-pyridyl)porphyrin (TMPyP) and tetra(4-sulfonatophenyl)porphyrin (TSPP) in a 1:1 stoichiometric ratio. Rod like crystals large enough for single crystal diffraction studies were grown by utilizing a nucleation and growth model described in our previous work. The unit cell of the TMPyP:TSPP crystals is monoclinic P21/c and the cell constants are a = 8.3049(11) Å, b = 16.413(2) Å, c = 29.185(3) Å, β = 92.477(9)°. These crystals have smooth well defined facets and their internal structure consists of highly organized molecular columns of alternating porphyrin cations and anions that are stacked face to face. For the first time crystal morphology (habit) of an ionic porphyrin solid is predicted by using the crystal structure data and applying attachment energy (AE) model. The predicted habit is in good agreement with the experimental structural morphology observed in AFM and SEM images of the TMPyP:TSPP crystalline solid. The TMPyP:TSPP crystals are non-conducting in the dark and are photoconducting. The photoconductive response is significantly faster with excitation in the Q-band (Red) than with excitation in the Soret band (blue). DFT calculations were performed to determine their electronic band structure and density of states. The TMPyP:TSPP crystalline system is a useful model structure that combine the elements of molecular organization and morphology along with theory and correlate them with electronic and optical electronic properties.