Low-bandgap conjugated polymers with photocurrent response over 1000 nm

Low-bandgap conjugated polymers with photocurrent response to near-infrared (NIR) wavelength are the basis of optoelectronic technologies such as semitransparent organic photovoltaics (STOPVs), NIR polymer photodetectors (PPDs), ambipolar field-effect transistors (FETs), photoacoustic (PA) imaging and photothermal therapy (PTT). Compared with inorganic-based photodetectors, PPDs, based on low-bandgap conjugated polymers with the chemical structures easy to be tuned, can achieve a wide range of spectral responses. On the other hand, this kind of polymers can enhance the short-circuit current ( J SC ) in TOPV by extending the absorption spectrum range. In this review, our focus will be on the development of low-bandgap conjugated polymers extending over 1000 nm and the performance of PPDs or OPVs. The perspective article summarizes the design strategy of such polymers, the derivation process of the useful heterocycles, absorption, bandgap, and energy levels. Thereafter, we will draw attention to the challenges and the possible research direction in the future to provide readers with a deeper understanding of the design of NIR polymers. Graphical abstract