Exploration of Syntheses and Functions of Higher Ladder-type π-Conjugated Heteroacenes

Ladder-type heteroacenes with well-defined structures and highly planar and delocalized π-electrons are an important class of materials for potential applications in organic electronics. The incorporation of heteroatoms into the ladder backbone allows for tuning optical-electronic properties and crystal structures in the solid state. Significant progress in synthesis and physical studies of a number of fascinating ladder molecules has been achieved. This review discusses progression in synthetic methods, structural characterization, and applications of ladder-type heteroacenes. Ladder molecules with delocalized π-systems, well-define structures, and tuneable optical and electrical properties are challenging synthetic targets. The development of these molecules allows for detailed investigation of their solid structures, which will provide the basis for theoretical investigation of the optoelectronic properties of these materials. Because the importance and performance of organic electronic devices have both improved significantly over the last 5 years, new materials with much enhanced mobility and tuneable optical properties will be a valuable addition and facilitator. The clear advantages of the ladder structures can be fully utilized for these purposes. This review provides a timely summary of recent advances in the latest synthetic approaches and challenges and highlights the wide range of applications of ladder molecules with more than six aromatic rings in the molecular backbone. The past 5 years have witnessed significant advances in the synthesis and characterization of ladder-type molecules. These molecules, which have well-defined structures and highly planar and delocalized π-electrons, are an important class of materials for potential applications in organic electronics. The incorporation of heteroatoms into the ladder backbone allows for tuning optical-electronic properties. The unique structures, properties, and potential applications of ladder-type molecules have attracted great interest for researchers.