Wide Bandgap Polymer Donors Based on Highly Twisted Biphenyl Imide for Efficient Organic Photovoltaics†

Comprehensive Summary A series of novel polymers based on highly twisted biphenyl imide and benzodithiophene have been designed and synthesized, exhibiting excellent thermal stability, strong absorption in the visible spectrum, and wide bandgaps. By strategically adjusting linkage positions and integrating thiophene bridges, the optical properties, energy levels of frontier orbitals, and interchain stacking of these polymers were meticulously tailored. Organic solar cells based on these polymer donors revealed that ZP4 , featuring 4,4’‐linkages and thiophene bridges, achieved the highest power conversion efficiency of 4.10%, which is comparable to that of analogous polymers based on more planar bithiophene imide. This study challenges the conventional belief that structural planarity is essential for high‐performance OPV polymers, underscoring the potential of non‐planar units and broader design strategies beyond planarity.