Printed SWCNT-Based p–n Junction Thin-Film Near-Infrared Photoresistors Enabled by a Sustainable Furan-Derived π-Conjugated Polymer

Abstract

Semiconducting single-walled carbon nanotubes (SWCNTs) are attractive for near-infrared (NIR) sensing but suffer from weak photocurrent due to large exciton binding energies. Here, we pair chirality-enriched (10,9)- SWCNT as the electron acceptor with a sustainable, furfural-derived π-conjugated polymer (PFEB) as the electron donor to fabricate lateral, resistor-type p-n heterojunction NIR photodetectors to facilitate exciton dissociation. Post-deposition thermal cleavage of PFEB’s carbamate side chains yields PFNB, which tightens polymer–nanotube contact and switches the dominant response of the sensors from ∼800 to ∼1000 nm. The optimized PFNB/(10,9)-enriched SWCNT device on SiO₂ substrates achieves EQE = 19.7%, R = 0.159 A W⁻¹, and D^* = 2.66 × 10⁸ Jones at 1000 nm and 1.0 V, while an all-printed device on a polyimide substrate reaches EQE = 6.47%, R = 0.0522 A W⁻¹, and D^* = 7.90 × 10⁷ Jones. Photoluminescence-excitation quenching (∼78%) and redshifts/broadening in (10,9)-enriched SWCNT optical bands evidence strong interfacial coupling and interfacial charge transfer. The devices require neither transparent electrodes nor complex stacks, and they are fabricated via ultrasonic micro-printing using picoliter ink volumes. This work demonstrates a scalable route to high-performance, low-power, and environmentally friendly NIR sensing.