Conjugated polymers with near-infrared (NIR) optical absorption: structural design considerations and applications in organic electronics

Conjugated polymers (CPs) have revolutionized soft-matter electronics by enabling the manufacture of non-toxic, low-cost, and mechanically robust materials and devices for various technologies, including organic photovoltaics (OPV), electrochromic devices (ECDs), organic field effect transistors (OFET), and organic bioelectronics. Coupled with breakthroughs in synthetic chemistry and structure-function properties, the advancements in organic electronics have been firmly intertwined with CP structural developments. Recent research efforts have focused on the molecular engineering of CPs to broaden the optical absorption to the near-infrared (NIR) region (>750 nm) to enable new capabilities in photon harvesting for photovoltaics, optical switching and detection, thermal energy management, active camouflage, and to tune energy levels to achieve n-type and ambipolar charge transport. This review presents a comprehensive overview of the design and synthesis of CPs with NIR optical absorption, and it describes their incorporation in established and emerging device applications. A central focus throughout is how the polymer structures can be tailored specifically for each application with included strengths and shortcomings. An emphasis is placed on recent and emerging polymer structures with an outlook on areas for future work.