Bent-Shaped p-Type Small-Molecule Organic Semiconductors: A Molecular Design Strategy for Next-Generation Practical Applications

Abstract

Significant progress has been made in both molecular design and fundamental scientific understanding of organic semiconductors (OSCs) in recent years. Suitable charge-carrier mobilities (μ) have been obtained by many high-performance OSCs (μ > 10 cm² V^-1 s^-1), but drawbacks remain, including low solution processability and poor thermal durability. In addition, since aggregation of OSCs involves weak intermolecular interactions, the molecules are perpetually in thermal motion, even in the solid state, which disrupts charge-carrier transport. These issues limit potential applications of OSCs. The present work examines a molecular design for hole-transporting (p-type) OSCs based on the "bent-shaped" geometry with specific molecular orbital configurations, which aims to enhance effective intermolecular orbital overlaps, stabilize crystal phases, suppress detrimental molecular motions in the solid state, and improve solution processability. The results indicated that such OSCs have high μ and suitable solution processability, and are resistant to ambient and thermal conditions, making them suitable for practical applications.