Design, synthesis, and properties of soluble intrinsic black polyimide bearing tetraphenylcyclopentadienone units

Abstract Black polyimides (BPIs) have gained increasing attention because of their growing demands in optoelectronic areas. However, the commonly used BPI containing carbon black suffers from the decreases of mechanical and electrical performances. In this work, a soluble intrinsic BPI (TPCPDFPPI) was prepared by the reaction of 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and a new diamine (TPCPDFPDA) bearing tetraphenylcyclopentadienone (TPCP) connected with benzene and fluorene units. TPCP grafted with benzene and fluorene units acted as a chromophore that shifted the absorption range of PI toward the long‐wave direction. The resulting TPCPDFPPI possessed whole visible‐light absorption characteristic and therefore exhibited high blackness and opacity. Additionally, TPCPDFPPI displayed superior solubility, mechanical and electrical performance. Theoretical calculations exhibited that the visible‐light absorption responsible for the blackness of TPCPDFPPI was chiefly ascribed to the HOMO to LUMO electron transition in the diamines, where the electrons were primarily migrated from the 2,5‐position aryl groups to the cyclopentadienone. This work offers a promising strategy for improving the overall properties of BPIs for photo‐electronic areas.