Near-Infrared Broadband Absorbing Polymer Acceptors for Flexible All-Polymer Photodetectors with High Detectivity

Compared to conventional inorganic detectors, all-polymer photodetectors (all-PPDs) have attracted significant attention in the field of flexible and wearable electronics owing to their unique mechanical properties. However, their practical applications are often hindered by a narrow spectral response range and limited sensitivity. In this work, we designed and synthesized three polymer acceptors with broad-spectrum absorption capabilities for use in all-PPDs, and systematically investigated the effect of acceptor unit composition on the overall polymer properties. Through comprehensive optical, electrochemical, and computational analyses, we found that the single-acceptor polymer P1-TT exhibits exceptional broadband response characteristics, attributed to the strong intramolecular donor-acceptor (D-A) effect. The photodetector based on P1-TT achieved a remarkable specific detectivity exceeding 10¹² Jones across a wide range of 300 to 870 nm under a low bias of -0.1 V, with a peak value of 3.6 × 10¹³ Jones at 700 nm. Moreover, it demonstrated a low dark current density (5.5 × 10^-11 A·cm^-2), a wide linear dynamic range (109.0 dB), and a fast response time (rise time/fall time = 2.12/3.59 μs), outperforming many existing acceptor materials. Benefiting from the excellent mechanical properties of the all-polymer blend film, P1-TT can be used to fabricate flexible device, and it also delivered a superior detectivity of 3.3 × 10¹³ Jones at 700 nm under a bias of -0.1 V. Practical application tests further verified its potential in optical communications, infrared signal detection, and biometric monitoring, demonstrating its promise for use in next-generation flexible optoelectronic systems.