All-polymer solar cells (All-PSCs) offer several distinct merits including superior thermal stability and flexibility. Here, we report a novel polymer acceptor PJ1 that exhibits a narrow band gap around 1.4 eV and a high extinction coefficient about 1.39×10⁵ cm^-1. When PJ1 is blended with donor polymer PBDB-T, all-PSC with a record power conversion efficiency (PCE) of 14.4% is achieved, which is mainly attributed to the broad absorption, efficient charge separation and collection, and low energy loss. The synergetic effects of molecular weight of PJ1 on the photovoltaic performance are also investigated. It is found that the increase in molecular weight can result in the red-shift of absorption along with slight enhancement of extinction coefficient, which therefore benefits photocurrent. In addition, all-PSC based on PJ1 demonstrate much better thermal stability than the control device based on small molecule acceptor (TTPBT-IC), as evidenced by the insignificant morphology change of PBDB-T:PJ1 versus excessive phase separation of PBDB-T:TTPBT-IC when annealed at 150 ^oC. Of particular interest is that the all-PSCs based on PBDB-T:PJ1 can retain high PCEs even when the thickness of photoactive layer is increased over 300 nm (PCE of 12.1%) or the device area is enlarged to 1 cm² (PCE of 13.0%).

全聚合物太阳能电池（All-PSC）具有几个独特的优点，包括卓越的热稳定性和柔韧性。在这里，我们报告了一种新型的聚合物受体PJ1，它在1.4 eV附近表现出窄带隙，在1.39×10 ⁵ cm ^-1处具有高消光系数。。当将PJ1与施主聚合物PBDB-T共混时，可实现具有14.4％的创纪录功率转换效率（PCE）的全PSC，这主要归因于广泛的吸收，有效的电荷分离和收集以及低的能量损耗。还研究了PJ1分子量对光伏性能的协同作用。发现分子量的增加可以导致吸收的红移以及消光系数的轻微提高，因此有利于光电流。此外，基于PJ1的全PSC表现出比基于小分子受体的控制装置（TTPBT-IC）更好的热稳定性，这由PBDB-T：PJ1的形态变化无明显变化与PBDB-T的过度相分离所证明：TTPBT-IC在150 ^o退火时C.特别令人感兴趣的是，即使当光敏层的厚度增加到300 nm以上（PCE为12.1％）或器件面积扩大到1 cm ²时，基于PBDB-T：PJ1的全PSC仍可以保留高PCE。（PCE为13.0％）。