Controllable Synthesis Of All-inorganic Halide Perovskite Nanocrystals And Their Applications

Halide perovskite nanocrystals?HP NCs?have triggered intensive attention due to their outstanding optoelectronic properties and great potential in many fields.Compared to organic-inorganic hybrid perovskite nanocrystals,all-inorganic halide perovskite NCs?IHP NCs?have many advantages,such as high stability,ultrahigh photoluminescence quantum yield?PLQY?and photoluminescence?PL?with narrow emission line-width,and so on,which makes them great candidates for diverse applications,including photovoltaic devices,light emitting diodes?LEDs?,lasers,photocatalysis and detectors.ILHP NCs have been reported by a muber of articles and some progress on synthesis and applictiaons has been made in the past few years.However,many problems and challenges still remain,such as the low stability and low efficiency.These problems severely limited the practical applications of IHP NCs.In this dissertation,we explored and explained the internal mechanism of the preparation base on synthetic process of IHP NCs and then find the way to improve the stability of the IHP NCs.Furthermore,we also designed and synthesized some composites based on ILHP NCs and tried to use this material for photocatalytic reduction of CO2.The specific researches are summarized as follows:1.The transformation of nonluminescent Cs4 Pb X6 NCs to highly luminescent Cs Pb X3 NCs on the interface between nonpolar solvent and water has been realized.A series of experiments have been designed to investigate the transformation process.Moreover,a novel Cs X-stripping mechanism has been proposed.2.By adding trioctylphosphine oxide?TOPO?into the reaction system,IHP NCs were successfully synthesized through a hot-injection method.The TOPO provided a strong protection for the NCs.Thus,the stability of the IHP NCs have been improved.Besides,the size of IHP NCs can be well tuned by controlling the reaction temperature after the introduction of TOPO.3.The composite of IHP and TiO₂ have been designed and synthesized.By signal coating of TiO₂ on the surface of NCs,we realized the surface modification of IHP NCs.The composite was used as photocatalyst for the reduction of CO2.After a preliminary attempt,this composite exhibited an excellent catalytic performance.