Rational Design of Black Polyimide With High Comprehensive Properties Derived From DBF-Based Chromophore

The market need for black polyimide (BPI) in microelectronics and optoelectronics has significantly increased. However, the current BPIs suffer from issues such as inadequate masking effectiveness, inferior electrical performance, and dimensional stability. 3,6-Di(furan-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DBF) is a typical dye that possesses excellent light-absorbing ability. In this work, a novel diamine (DBFRFPDA) with DBF-derived chromophores was successfully synthesized. Utilizing this newly developed diamine and pyromellitic dianhydride (PMDA), an inherent BPI (DBFRFPPI) was prepared. The spectral absorption of DBFRFPPI is greatly widened and red-shifted with the incorporation of DBF-based chromophores, thus achieving an exceptionally dark hue. DBFRFPPI exhibits a high cut-off wavelength (λ _cut) of 680 nm and a small CIE-Lab coordinate L* of 1.02. Moreover, DBFRFPPI shows a small coefficient of thermal expansion (CTE) and demonstrates outstanding thermal and electrical characteristics. The electronic transitions of DBFRFPPI were investigated using density functional theory. The findings demonstrate that the superior light absorption of DBFRFPPI is chiefly derived from the HOMO→LUMO+1 transition, which takes place within the DBF-based chromophore moiety. This intrinsic BPI with highly comprehensive properties has important applications in microelectronic fields, especially in flexible copper-clad laminate (FCCL).