Axially Chiral Organic Semiconductors for Visible‐Blind UV‐Selective Circularly Polarized Light Detection

• Published in: Advanced science 2024-04, Vol.11 (14), p.e2308262-n/a
• Main Authors: Kwon, Yejin, Jung, Je‐Yeon, Lee, Won Bo, Oh, Joon Hak
• Format: Article
• Language: English
• Subjects: binaphthyl; chirality; circularly polarized light; Design; Discrimination; Light; organic phototransistors; Scanning electron microscopy; self‐assembly; Semiconductors; Sensors
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202308262

Technologies that detect circularly polarized light (CPL), particularly in the UV region, have significant potential for various applications, including bioimaging and optical communication. However, a major challenge in directly sensing CPL arises from the conflicting requirements of planar structures for efficient charge transport and distorted structures for effective interaction with CPL. Here, a novel design of an axially chiral n‐type organic semiconductor is presented to surmount the challenge, in which a binaphthyl group results in a high dissymmetry factor at the molecular level, while maintaining excellent electron‐transporting characteristics through the naphthalene diimide group. Experimental and computational methods reveal different stacking behaviors in homochiral and heterochiral assemblies, yielding different structures: Nanowires and nanoparticles, respectively. Especially, the homochiral assemblies exhibit effective π–π stacking between naphthalene diimides despite axial chirality. Thus, phototransistors fabricated using enantiomers exhibit a high maximum electron mobility of 0.22 cm2 V−1 s−1 and a detectivity of 3.9 × 1012 Jones, alongside the CPL distinguishing ability with a dissymmetry factor of responsivity of 0.05. Furthermore, the material possesses a wide bandgap, contributing to its excellent visible‐blind UV‐selective detection. These findings highlight the new strategy for compact CPL detectors, coupled with the demonstration of less‐explored n‐type and UV region phototransistors. An organic semiconductor with axial chirality is proposed by linking two naphthalene diimides with a binaphthyl group. This innovative material demonstrates distinctive chiral self‐discrimination behavior and assembles into nanowires. It has potential applications as a phototransistor for selectively detecting circularly polarized light (CPL) in the UV region, in conjunction with possessing high electron mobility and excellent detectivity.