Band Gaps and Photocurrent Responses of Bulk and Thin‐Film Coordination Polymers Based on 3,6‐Di(1 H ‐imidazol‐1‐yl)‐9 H ‐carbazole

From a new rigid N‐donor ligand, 3,6‐di(1 H ‐imidazol‐1‐yl)‐9 H ‐carbazole ( L ), two coordination polymers (CPs) formulated as Cd L ( L1 ) · 3DMF ( 1 ; H 2 L1 = 4,4′‐carbonyldibenzoic acid, DMF = N , N ‐dimethylformamide) and Cu 2 L 2 (SO 4 ) ( 2 ) were synthesized solvothermally and structurally characterized by single‐crystal X‐ray diffraction. CP 1 exhibits a two‐dimensional (2D) structure, and CP 2 shows one‐dimensional (1D) chains. The two CPs exhibit different quasireversible redox properties and possess very weak photoluminescence properties. Density functional theory (DFT) calculations and experimental results show that CP 1 has a wider band gap than that of CP 2 . Notably, CP 2 produces a higher photocurrent density than that of CP 1 upon visible‐light illumination, which is also in agreement with their Nyquist plots and Mott–Schottky curves. Thin‐film CP 1 was obtained by physical exfoliation in methanol and shows more active electrochemical behavior and enhanced photoresponse relative to those of bulk CP 1 .