Axially Chiral Semiconducting Polymers Enabling NIR Circularly Polarized Light‐Sensing Phototransistors and Neuromorphic Synapses

ABSTRACT Waveplate‐free detection of near‐infrared (NIR) circularly polarized light (CPL) has been limited by the absence of materials that simultaneously exhibit strong NIR circular dichroism and efficient charge transport. Here, we present a family of axially chiral conjugated polymers, S ‐ and R ‐pDPP4TBN‐X , designed by grafting S/R ‐6,6′‐dimethoxy‐1,1′‐binaphthyl ( S/R ‐MeBN) onto a diketopyrrolopyrrole (DPP)‐bithiophene backbone. By tuning the MeBN: DPP ratio, the polymers exhibit extended absorption up to ∼1000 nm, enhanced circular dichroism in the 500–870 nm region, and optimized thin‐film morphology for charge mobility. Organic phototransistors based on S/R ‐pDPP4TBN‐10 achieve hole mobilities up to 0.13 cm 2 V −1 s −1 , responsivities as high as 12.52 A W −1 , detectivities on the order of 10 11 Jones, and dissymmetry factors ( g Iph ) of 0.30 and ‐0.34 under 808 nm CPL, enabling unambiguous discrimination of left‐ and right‐handed light. Beyond static sensing, these devices emulate synaptic plasticity under CPL stimulation and, when coupled with an artificial neural network, deliver classification accuracies exceeding 95%. This work establishes a modular design paradigm for compact, NIR‐active CPL sensors that integrate high charge transport, pronounced chiroptical response, and neuromorphic function, paving the way for photonic encryption, wearable optoelectronics, and bioinspired computing platforms.