Metal Complexes Based on 2‐[5‐(3,5‐Dibromophenyl)‐2H‐1,2,4‐triazol‐3‐yl]pyridine and Their Composites with CH3NH3PbI3: Structures, Band Gaps, and Enhanced Optoelectronic Properties

Abstract

From 2‐[5‐(3,5‐dibromophenyl)‐2H‐1,2,4‐triazol‐3‐yl]pyridine (HL), three metal(II) complexes formulated as NiL2(HL)·DMF (1; DMF = N,N‐dimethylformamide), NiL2 (2), and CuL2 (3) were synthesized solvothermally and characterized by single‐crystal X‐ray diffraction. Among them, 2 and 3 are isostructural, except for the different metal(II) centers in their structures. The three metal(II) complexes all exhibit mononuclear structures but possess different band structures. Density functional theory (DFT) calculations revealed that 2 and 3 are semiconductors, and their perovskite CH3NH3PbI3 (P) composite materials, 2@P and 3@P, were synthesized. The largest photocurrent densities obtained for the two composite materials are much higher than those obtained for the corresponding complexes under intermittent visible‐light illumination (λ > 420 nm), as the suitable band gaps and matched energy levels of the complexes and P prevent the recombination of photoinduced electron–hole pairs. In addition, the stable photocurrent responses of the two composite materials in aqueous solution are associated with coverage of the surface of P by the insoluble complex, which improves the water resistance of P.