Solvent-Desorption-Induced Formation of a Long-Period Polymorph Yielding a High-Performance Porphyrin-Based Organic...

Polymorphism is common in organic semiconductors, yet experimentally accessible crystal structures are often limited to thermodynamically favored phases formed under equilibrium crystallization conditions. Here, we report a structural transformation in single crystals of 5,15-bisphenyl-tetrabenzoporphyrin (Ph-BP) triggered by the removal of intercalated o-dichlorobenzene. This transformation induces a 90° rotation of the π-stacking direction between adjacent layers, giving rise to a previously unobserved long-period polymorph characterized by the periodic alternation of two distinct herringbone packing motifs. The solvent-desorption-induced transformed phase can also be formed on Si/SiO₂ substrates and affords single-crystal organic field-effect transistors exhibiting hole mobilities higher than those of devices based on the previously reported Ph-BP polymorph. These findings suggest that solvent-desorption-induced structural transformations provide a viable strategy for accessing hidden polymorphs with enhanced semiconductor performance.