High-performance flexible circularly polarized light photodetectors based on chiral n-type naphthalenediimide-bithiophene polymers

Chiral π-conjugated polymers are key for advancing flexible circularly polarized light (CPL) photodetectors due to their mechanical flexibility, high sensitivity, and compatibility with large-scale fabrication. However, achieving strong CPL detection and efficient charge transport in flexible chiral photodetectors remains challenging. Here, we present a novel n-type chiral π-conjugated polymer (S/R)-P(NDI2MH-T2) for high-performance flexible CPL photodetectors. The polymer exhibits enhanced chiroptical activity after annealing, with significant improvement in |g_abs| at 382 nm (2.34 × 10⁻²) and at 670 nm (1.38 × 10⁻²), which is attributed to improved polymer chain stacking and exciton coupling, as confirmed by molecular dynamics simulations. The phototransistors show high electron mobility (7.9 × 10⁻² cm² V⁻¹ s⁻¹), photoresponsivity (92 A W⁻¹), and detectivity (1.1 × 10¹² Jones). A flexible CPL photodetector fabricated with polydimethylsiloxane and polyethylene naphthalate substrates demonstrates reliable CPL detection with |g_ph| of 0.043. This work highlights the potential of chiral π-conjugated polymers for efficient flexible CPL photodetectors.