Flexible near-infrared organic photodetectors for emergent wearable applications

With the evolution of Industry 4.0, next-generation wearable devices have come under the spotlight, where organic electronics are playing an important role due to their flexible form factor, high performance, and integration capability. Designed to conform to soft and dynamic surfaces, flexible organic photodetectors (OPDs) and integrated arrays stand out for their application potential in non-invasive biosensing and bio-imaging, with inherent advantages in mitigating motion artifacts – a notable limitation of traditional, rigid photodetector systems. Leveraging the near-infrared (NIR) spectrum's capability for deep skin penetration and minimal scattering in human tissues, flexible NIR OPDs are especially capable of precise diagnostics with enhanced signal quality. The adaptable form factor further broadens their potential for applications in human-environment interaction, marking a notable shift towards more responsive and intelligent wearable technologies. This review summarizes the latest challenges and breakthroughs of flexible NIR OPDs, emphasizing effective strategies toward flexible and high-performance device units and integrated systems. We further discuss the remaining challenges and outlook on the vast potential of flexible NIR OPDs in reshaping our interaction with our surroundings.