Investigation Of Lead-free Inorganic Antimony Halide Perovskite And Its Optoelectronic Devices

Perovskite has been widely used in a number of fields due to their superior photoelectric properties.Latest reports have revealed that the photoelectric conversion efficiency of perovskite solar cells have been rapidly improved from the initial 3.8%to 24%in past few years.As for light-emitting diodes applications,the light emitting diodes have been developed previously exhibit internal quantum efficiency exceeding 20%with tunable light emission spectra.Despite their processing advantages,perovskite optoelectronic materials suffer from several drawbacks that need to be overcame before the industrial bloom of technology.Topmost among these materials are the Pb-based perovskites,however the toxicity of Pb and the intrinsic instability of these materials limited their large-scale applications.Following these problems,herein we reported a stable inorganic lead-free antimony-based perovskite.The basic properties of this material were investigated by growing perovskite single crystals.Antimony-based perovskites ware applied to the light-emitting diodes and solar cells.The research contents are expanded to the following sections:?1?Growth of Cs₃Sb₂X₉?X=Br,I?perovskite single crystals and study of their basic physical properties.The Cs₃Sb₂Br₉ and Cs₃Sb₂I₉ single crystals were grown by slow evaporation method and temperature-lowering method respectively.XRD characterization shows that Cs₃Sb₂Br₉ perovskite is layered structure while Cs₃Sb₂I₉ hold two structures of dimer and layered.Basic optoelectronics on single crystals revealed that the Cs₃Sb₂X₉material has a high absorbance and a strong photoelectric response.The band gap of the Cs₃Sb₂Br₉ single crystal is 2.36 eV.The band gap of dimer Cs₃Sb₂I₉ single crystal is 2.40eV,while the band gap of layered single crystal is 2.05 eV.It is predicted that the Cs₃Sb₂X₉material has a huge prospect for photovoltaic devices applications.?2?Synthesis of Cs₃Sb₂X₉ quantum dots and research on light-emitting diodes based on Cs₃Sb₂X₉ materials.In this paper,lead-free all-inorganic Cs₃Sb₂X₉ perovskite quantum dots were prepared by optimized ligand-assisted precipitation method.The Cs₃Sb₂X₉quantum dots with high fluorescence quantum yield were prepared by optimizing the reaction conditions with analyzed theory.The quantum yield of the Cs₃Sb₂Br₉ blue quantum dot is as high as 46%.Testing and analysis revealed that the quantum well structure caused by the enrichment of halogen ions on the surface of quantum dots has a very positive effect on the quantum yield.Moreover,the self-exciton binding energy of Cs₃Sb₂Br₉ quantum dots is 530 meV,which provides a theoretical basis for the preparation of light-emitting diodes.Finally,we mixed the blue quantum dots of Cs₃Sb₂Br₉,the yellow quantum dots of Cs₃Sb₂I₉and the red phosphor to prepare warm white LEDs.?3?Preparation of Cs₃Sb₂I₉ Thin Films and research on solar cell is based on Cs₃Sb₂I₉ perovskite.Herein,a layered structure of Cs₃Sb₂I₉ film was prepared by hydrochloric acid assisted solution method,and the structure of perovskite solar cell is FTO/TiO₂/Cs₃Sb₂I₉/Au.By comparing the presence or absence of hydrochloric acid-assisted perovskite film and solar cell,a device with efficiency of 1.2%,open circuit voltage of 0.61V,and short circuit current of 3.55 mA cm^-2 was prepared.The defect analysis of all inorganic lead-free Cs₃Sb₂I₉ solar cell devices was carried out.It was found that the device had shallow defects along with certain influence on device performance.All-inorganic structure of the device is responsible for the solar cell stability.