Noise‐Blocking Interfacial Lamination of Small‐Molecule Acceptors for Enhanced Signal Clarity in Organic Photodetectors

ABSTRACT This study demonstrates an excellent interfacial layering technique for the full‐coverage deposition of the carbon‐based small‐molecule acceptor Y6‐BO, forming a uniform and dense sandwich interface between the bulk heterojunction layer and the cathode to effectively suppress dark current. Organic photodetectors (OPDs) possess significant potential in high‐performance light‐sensitivity applications, but introducing a charge injection barrier is critical for effective dark current suppression. However, performance degradation often occurs due to solvent‐induced interface damage during this multilayer fabrication process. The proposed process design prevents solvent penetration during stacking and minimizes interface degradation while ensuring reduced defect density and improved layer uniformity. Compared with spin‐coated Y6‐BO devices, the OPD with laminated Y6‐BO exhibits a 2.19‐fold reduction in dark current and enhanced shot‐noise‐limited detectivity owing to suppressed trap formation, increased hole injection barrier, and optimized charge transport. Furthermore, the laminated Y6‐BO device exhibits a higher cutoff frequency of −3 dB and faster response time, confirming its suitability for high‐speed photodetection. As a photoplethysmography sensor, the device demonstrates superior stability and signal clarity, enabling accurate detection of cardiovascular activity even after prolonged exposure to ambient conditions. The results suggest that interfacial lamination is an effective strategy to prevent solvent‐induced interfacial degradation and enhance OPD performance, making it a promising approach for next‐generation biomedical sensing and near‐infrared imaging applications.