Achieving Efficient Narrowband Polarized Light Detection at Tunable Central Wavelengths in Organic Polymers via Optical Microcavities

ABSTRACT Achieving highly responsive, narrowband detection of polarized light in organic semiconductor devices remains a significant challenge. In this study, an ultrahigh polarization‐sensitive response, exhibiting an external quantum efficiency well in excess of 100% and a dichroic ratio of 15.12, is realized by stack‐coupling a friction‐aligned P3HT film, which has been frictionally aligned using a velvet cloth, with a classical binary blend system of P3HT:PC 61 BM (100:2). Furthermore, incorporating an Al/ITO/Al optical microcavity enables the narrowband sensing of ultraviolet polarized light, exhibiting a full width at half maximum of ∼38 nm at a central wavelength of 350 nm. Additionally, an asymmetric optical microcavity based on an Ag/ZnO/Al structure is designed to resonate at 610 nm; by effectively suppressing the interference of second‐order Fabry–Pérot resonances, the highly responsive, narrowband detection of polarized light in the visible red‐light spectrum, with a full width at half maximum of approximately 42 nm, is successfully accomplished. This proposed strategy, wherein the energy band matching characteristics between the polarized absorption layer and the tunneling‐inducing layer are comprehensively accounted for, effectively mitigates higher‐order Fabry–Pérot resonance interference, thereby demonstrating superior tunable spectral selectivity and highly responsive, polarization‐sensitive detection performance. Ultimately, we demonstrate the potential of these rationally designed detectors in single‐wavelength digital encrypted communication systems. This work provides a novel design paradigm and practical reference for advancing organic polarization‐sensitive narrowband photodetectors.