Low band gap polymers for photovoltaic device with photocurrent response wavelengths over 1000 nm

To pursue high power conversion efficiency (PCE) of polymer solar cells (PSCs), many new semiconducting polymers with low band gaps have been developed in the past several years. In this perspective paper, we focused on super low band gap photovoltaic polymers with photocurrent response extending over 1000 nm. This kind of micrometer-response polymers (μmR-polymer) could increase the short circuit current (JSC) due to better match of absorption spectra of the polymers with the solar irradiation and show tremendous potential for application in tandem solar cells and transparent solar cells. The necessary conditions for the design of this kind of μmR-polymers are discussed. Furthermore, the remaining problems and challenges, and the key research direction in near future are discussed.