Organic semiconductors possess unique photon absorption characteristics that result from their highly polarizable π-electronic structures. Although organic semiconductors have become viable alternatives to their well-established inorganic counterparts there is still a continuing need for research in controlling their composition and structure since those factors determine how they function. Consequently, a good fundamental understanding of structure–property relationships is essential in designing and building high performance, stable, and durable molecular materials and is one of the main scientific challenges for advancing organic optoelectronic technology.

The work that we will present is a detailed structure–property study of ionic porphyrin based semiconductors using both experiment and theory. Nano to millimeter size crystalline binary porphyrin structures were synthesized reproducibly from oppositely charged synthons and characterized using XRD, AFM, SEM, DRS, UV-visible, and photoconductivity measurements. The photoconductive properties of the porphyrin materials are linked with their molecular organization and morphology. Electronic band calculations help explain the experimental photoconductivity measurements and provide guidelines for future structure modification to optimize charge transport properties in these π-conjugated systems. These studies are the first to combine structure determination, electronic band calculations, and experiment in a unified approach for these materials.