Trivalent-Conjugated-Cation Layered Lead Chloride (Tptz)Pb2Cl7: Crystal Structure, Electronic Properties, and Photodetection

Abstract Two-dimensional (2D) layered perovskites offer a versatile platform for exploring hybrid halides with tunable optoelectronic properties, owing to their structural diversity and enhanced interlayer coupling. Herein, we report a novel Pb-based 2D layered perovskite (Tptz)Pb2Cl7 (Tptz = 2,4,6-tri(4-pyridyl)-1,3,5-triazine), in which trivalent conjugated Tptz3+ cations are incorporated into this structural family. Single-crystal structure analysis reveals that its structural connectivity resembles the [H3tib]Pb2Br7-type architecture, and DFT calculations further show that strong C–H...Cl hydrogen bonds between the [Pb2Cl7]3– framework and Tptz3+ cations facilitate efficient interlayer carrier transport. More intriguingly, the conjugated cations directly contribute to the band structure, inducing anomalous bandgap narrowing that extends the absorption edge into the visible region, as evidenced by the deep-yellow crystal color. Benefiting from these synergistic effects, the (Tptz)Pb2Cl7 single-crystal photodetector achieves an outstanding on/off ratio of 1.71 × 104, a linear dynamic range (LDR) of 101.83, and a specific detectivity (D*) of 8.02 × 1010 Jones, comparable to those of state-of-the-art Br/I-based perovskite single-crystal devices. Moreover, the device exhibits self-powered photoresponse to X-ray irradiation at 0 V, highlighting its potential for low-power radiation detection.