Naphthalenediimide/Iodobismuthate Hybrid Heterostructures: Water Resistance and Long-Lived Charge-Separated States

Organic–inorganic hybrid iodobismuthate perovskites have become promising semiconductive materials for their environmentally friendly and light-harvesting characteristics. However, their low-dimensional bismuth-iodide skeletons result in poor charge-separation efficiency, limiting their application in optoelectronic devices. To address this issue, the donor–acceptor (D–A) heterostructures have been introduced to the iodobismuthate hybrid materials by incorporating an electron-deficient N, N ′-bis(4-aminoethyl)-1,4,5,8-naphthalene diimide (NDIEA) as the electron acceptor and organic counterpart. Five naphthalenediimide/iodobismuthate hybrid heterostructures, named (H 2 NDIEA) 1.5 ·Bi 2 I 9 ·3DMF ( 1 ), H 2 NDIEA·[Bi 2 I 8 (DMF) 2 ]·2DMF ( 2 ), (H 2 NDIEA) 2 ·Bi 4 I 16 ·2H 2 O·4MeOH ( 3 ), (H 2 NDIEA) 2 ·Bi 4 I 16 ·8H 2 O ( 4 ), and [(H 2 NDIEA) 2 ·Bi 6 I 22 ] n ·4 n H 2 O ( 5 ) (DMF = N, N -dimethylformamide), were synthesized. Their crystal structures, water stabilities, charge-separated behaviors, and electrical properties have been studied through experimental and computational investigations. The results revealed that hybrids 3 – 5 exhibited high water resistance attributed to their tightly packed structures and robust H-bonds between solvent molecules and organic–inorganic supramolecular frameworks. Density functional theory calculations confirmed characteristic type-IIa band alignments of all the five hybrids, facilitating to the photoinduced charge separation. Moreover, the closer contact caused by the strong anion−π interactions between electron donors and acceptors in hybrid 5 leads to the long-lived charge-separated states and improved electrical properties compared to the other hybrids.