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

Abstract

From a new rigid N‐donor ligand, 3,6‐di(1H‐imidazol‐1‐yl)‐9H‐carbazole (L), two coordination polymers (CPs) formulated as CdL(L1)·3DMF (1; H2L1 = 4,4′‐carbonyldibenzoic acid, DMF = N,N‐dimethylformamide) and Cu2L2(SO4) (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.