High‐Performance Organic Narrow Dual‐Band Circular Polarized Light Detection for Encrypted Communications and Color Imaging

Conventional circularly polarized light (CPL) detectors necessitate several optical elements, posing difficulties in achieving miniature and integrated devices. Recently developed organic CPL detectors require no additional optical elements but usually suffer from low detectivity or low asymmetry factor (g‐factor). Here, an organic CPL detector with excellent detectivity and a high g‐factor is fabricated. By employing an inverted quasi‐planar heterojunction (IPHJ) structure and incorporating an additional liquid crystal film, a CPL detector with an outstanding g‐factor of 1.62 is developed. Unfavorable charge injection is effectively suppressed by the IPHJ structure, which reduces the dark current of the organic photodetector. Consequently, a left CPL detectivity of 6.16 × 1014 Jones at 640 nm is realized, surpassing all of the latest photodiode‐type CPL detectors. Adopting a liquid crystal film with adjustable wavelengths of selectively reflected light, the hybrid device achieves narrow dual‐band CPL detection, varying from 530 to 640 nm, with a half‐maximum full width below 90 nm. Notably, the device achieves excellent stability of 260 000 on/off cycles without attenuation. To the best of the authors’ knowledge, all these features have rarely been reported in previous work. The CPL detector arrays are also demonstrated for encrypted communications and color imaging. A facile strategy is described to achieve a high‐performance narrow dual‐band circular polarized photodetector via combining light‐driven cholesteric liquid crystal films with a photodiode‐type photodetector. A super‐high dissymmetry factor of 1.62, left‐handed circularly polarized light detectivity of 6.16 × 1014 Jones, and narrow dual‐band circularly polarized light detection, changing from 535 to 725 nm, with a half‐maximum full width of less than 90 nm is realized.