Synthesis And Characterization Of Cesium Lead Halide Perovskites Nanocrystals

In the push to meet the renewable energy needs of modern society,it is essential to develop inexpensive and environmentally friendly energy conversion and storage systems.Photovoltaic research and development has been growing rapidly to make use of the world's most abundant and clean energy source,sunlight.Historically,conventional photovoltaics have been expensive due to the complex fabrication procedures and high price of raw materials,and this has directly motivated a burgeoning field of research in solar technologies fabricated from fundamentally low-cost materials employing inexpensive fabrication methods.In the past few years,the field of halide perovskites has been growing rapidly because of their unique optical and electronic properties.The major breakthrough that renewed the interest in this old class of compounds came in 2012 where both CsSnI3 and CH3NH3PbI3 were employed to fabricate high efficiency all-solid-state solar cells.Since then,people pay lots of attentions on perovskites.Previous studies have reported that these perovskites exhibit a large absorption coefficient over a broad spectral range,high charge carrier mobility,small exciton binding energy,and long exciton diffusion length.The fabrication of thin films by solution-based processing offers advantages of cost-effectiveness and large-scale manufacture.Perovskites also exhibit promising photoluminescence quantum efficiencies of greater than 80% and lasing with low thresholds,making them promising candidates for efficient applications in laser and light-emitting diodes?LEDs?.The photoconversion efficiency of perovskites solar cells has been improved from 3.8 % to 20 %.Organic–inorganic lead halides have been extensively investigated because of their excellent optoelectronic properties,colloidal all-inorganic cesium lead halide NCs remains relatively unexplored.Colloidal all-inorganic cesium lead halide NCs have only emerged fairly recently and represent a new class of optical materials with outstanding optical gain signatures and the combined advantages of both the NCs and halide perovskites,there are still many problems,it is worthy for our further research.In this article,we report the large-scale synthesis of spherical CsPbX3 NCs via a one-pot approach by direct heating of all precursors in octadecene?ODE?in air.Increasing the reaction temperature in the presence of various reactants allows for convenient tuning of the luminescence color of the resulting NCs from the ultraviolet?UV?to the near-infrared?NIR?regions through simple control of particle size and composition.The photoluminescence?PL?quantum yield of the asprepared NCs was as high 87 % despite the lack of post-synthesis and surface modification procedures.This facile single-step non-injection strategy provides a versatile route to prepare low-cost high-quality CsPbX3 NCs with interesting emission colors for practical applications.Besides,we have first do the research on Mn²⁺ drop all-inorganic cesium lead halide NCs.We introduce a facile synthetic approach for producing Mn²⁺ doped CsPbX3?Mn:CsPbX3?NCs with finely tunable anion content.This is accomplished by directly synthesizing Mn:CsPbCl₃ NCs with nucleation droping,followed by anion exchange to create NCs of Mn:CsPbBr3,Mn:CsPbI3,and those of mixed anion content.We have studied the mechanism of Mn²⁺doped CsPbX3 and the effects of different Mn²⁺ doping concentrations.These NCs represent a truly unique testbed for the study of host-dopant interactions,as well as a versatile material class for the development of technologies that can exploit tunable Stokes shift or dual-color emission.