Progress in Metal Phthalocyanine-Based Organic Field-Effect Transistors

Phthalocyanines (Pcs), metal phthalocyanines (MPcs), and their supramolecular assemblies have emerged as pivotal materials in molecular electronics due to their exceptional chemical robustness, electronic tunability, and structural versatility. Despite the inherent insolubility of unsubstituted Pcs, the incorporation of different metal ions into the central cavity of the macrocyclic core significantly improves the solubility, processability, and charge transport characteristics. Various MPcs exhibit remarkable electrical conductivity, chemical stability, and semiconducting behavior, rendering them highly suitable for integration into organic field-effect transistors (OFETs) and flexible electronic systems. Their capability to function as n-, p-, or ambipolar semiconductors further enhances their utility in diverse optoelectronic applications. This review records the historical milestones and contemporary progress in MPc-based OFETs, tracing the discovery of phthalocyanines starting from 1907 and CuPc synthesis in 1927, and focusing on OFET adoption from the 1980s onward. We analyze their structural, optical, and electronic properties as well as fundamental OFET operation principles, including device architecture and charge transport mechanisms. Emphasis is placed on interface engineering, especially via self-assembled monolayers (SAMs), which modulate interfacial dipoles to optimize the charge injection, carrier density, and threshold voltage. Surface treatments and dielectric layer design critically influence molecular orientation, grain size, and trap density, thereby enhancing the mobility and device stability. Importantly, the review emphasizes the practical significance of MPcs in enabling cost-effective, flexible, and stable OFETs, thereby providing a valuable insight for researchers and engineers aiming to realize next-generation organic electronics leveraging MPc materials.