One-dimensional lead iodide hybrid compound shows a broad-band light emission

1. One-dimensional lead iodide hybrid compound shows a broad-band light emission The scanning electron microscope (SEM) image of 1D lead iodide hybrid is shown in Fig. 5. A large number of micro rods were obtained in II. This crystal shape is completely different from the microplate shape of the initial rhenium cluster compound (I) (Fig. S4). The length of micro rods varies from a few micrometers to tens of micrometers. Rhenium cluster complex (I) and 1D lead iodide hybrid (II) dissolved in DMF were excited by laser pulses at 340 nm wavelength, and optical measurements were carried out at 298 K. The emission spectrum was recorded in the wavelength range of 400 ~ 900 nm. The absorption, excitation and emission of I are shown in Figure S5. The emission spectra of compounds I and II in solution and solid were similar to Fig. S6. Fig. 7C shows the brown needle like crystals of II. Under UV irradiation（ λ = 365 nm), the II compound in DMF showed bright orange emission (Fig. 7a). In order to further characterize the optical properties of II, its ultraviolet visible absorption and photoluminescence (PL) spectra were obtained (Fig. 7b). The ultraviolet visible absorption spectrum shows that there is obvious absorption in the range of 200 ~ 450 nm, and a weak broadband absorption band around 330 nm, which may be caused by the π electron transition in the conjugated organic ligand molecule. Under the excitation of 340 nm, 1D lead iodide hybrid (II) has a broad band, with a peak at 634 nm, spanning 550 nm to 850 nm, covering the entire visible range (Fig. 7). The luminescence spectra of I and II were measured in the solid state (Fig. 8). The maximum characteristic emission of the {re6s8} core observed in compound (I) was 648 nm (blue line in Fig. 8), the compound was assigned to rhenium cluster, and the maximum of compound (II) at 634 nm (red line in Fig. 8) changed color. This result shows that the one-dimensional lead iodide hybrid compound (II) shows a broad-band light emission similar to that of the rhenium nuclei, and because the lead iodide anion overlaps with the rhenium nuclei in the range of 550, the maximum peak of the re radicals moves from 648 nm to a shorter wavelength of 634 nm, as shown in Fig. 8. The absorption and emission spectra of one-dimensional lead halide hybrid show a large Stokes shift of 310 nm. In 2017, yuan and colleagues reported a one-dimensional organic lead bromide perovskite (c4n2h14pbbr4), which showed wide emission and reached a maximum at 475 nm. In 2019, Biswas and colleagues synthesized one-dimensional perovskite [(H2O) (c6h8n3) 2pb2br10], which also produced efficient blue and white luminescence at about 560 nm. Recently, Feng and colleagues reported a series of

2. perovskites with one-dimensional shared faces; These materials have wide band blue and white light emission with a maximum peak of about 500 nm. In this study, compared with two-dimensional and one-dimensional lead halide perovskites including ammonium ions, the emission spectrum of one-dimensional lead halide perovskites encapsulated by rhenium cluster cations shows strong color change emission, usually showing characteristic peaks in the purple to green region. To test the moisture resistance of compound (II), the II solution in DMF was exposed to air at room temperature for 3 months. The emission of compound (II) comes from [re6s8 (PZH) 6] 2 + and [pb3i8 (DMF) 2] 2 − in solution. The results showed that [re6s8 (PZH) 6] 2 + and [pb3i8 (DMF) 2] 2 − did not decompose after 3 months. Powder X-ray diffraction also confirmed the stability of {[re6s8 (PZH) 6] [pb3i8 (DMF) 2]} · 6 (DMF) solid phase, as shown in Fig. 9. This evidence indicates that the one-dimensional lead iodide hybrid is stable in the ambient atmosphere. The 650 nm time-resolved PL decay curve of compound (II) at 300 K was obtained by double exponential function fitting, with an average PL lifetime of 5.25 μ s. 3.77% higher than that of compound (I) μ S is increased by a value (FIG. 10). Finally, the band gaps of the indirect transition model and the direct transition model are calculated by using tauc function. Tauc diagram best fits the direct band gap model; Therefore, the energy band gap of compound (II) obtained by the direct transition model is about 2.7 ev (FIG. 11). This band gap is a characteristic of low dimensional perovskite materials, and exciton absorption is stable at room temperature. The band gap is similar to that of other one-dimensional perovskites such as cspbi3 and [tetrabutylammonium] [pbi3] (2.76 EV).