Beyond Intrinsic Limits: Polarization‐Sensitive Carrier Dynamics Amplify Subtle Intrinsic Optical Anisotropy into Giant Linear Dichroism

ABSTRACT Filterless polarization‐resolved photodetection is attractive for compact optoelectronic systems, but its polarization contrast is fundamentally constrained by the low intrinsic absorption anisotropy of semiconductors. Here, we introduce polarization‐sensitive carrier dynamics (PSCD), a design principle that shifts polarization discrimination from static absorption anisotropy to the time evolution of photocarrier populations. We implement PSCD in a nonvolatile floating‐gate phototransistor by integrating a molecularly thin p‐type organic single crystal with a two‐dimensional covalent organic framework floating gate. Orthogonal linearly polarized light generates different photogeneration rates in the anisotropic crystal, which induce distinct optical‐erasure kinetics and temporally divergent recovery of the channel hole population. Consequently, the absorption linear dichroism ratio (LDR) of 3.4 is dynamically amplified by over four orders of magnitude, reaching a transient photocurrent LDR of 3.6 × 10 4 under optimized bias conditions. The device further maintains strong polarization discrimination under partially polarized illumination, achieving a transient photocurrent LDR of 9.8 × 10 2 at a degree of linear polarization of 0.3. These results establish time‐domain amplification of weak optical anisotropy through carrier‐dynamic modulation as a strategy for filterless, high‐contrast polarimetric sensing in compact optoelectronic platforms.