Encapsulation Of Lead Halide Perovskite Quantum Dots And Their Applications In Fluorescence Sensing

Recent years,lead halide perovskites(LHP)are emerging as the most attractive semiconducting materials in photovoltaic research,which could be used to fabricate solar cells with efficiency over 20%.At the same time,perovskite quantum dots(QDs)have been synthesis through various ways,and have shown extraordinary features over conventional Cd QDs,such as high photoluminescence quantum yield(up to 100%),tunable emission wavelength over entire visible range(400-700nm),low temperature synthesis route.These remarkable properties make the LHP QDs became building blocks for next generation of optoelectronic devices,including solar cells,light emitting diodes(LEDs),light bump lasers and photodetectors.However,these LHP QDs are suffering from poor instability toward moisture/oxygen/polar and protic solvent and thermal degradation,which hinder their fundamental studies and further applications.In this dissertation,research works are focus on the encapsulating of LHP QDs into crystalline matrix,and by using these solid state lighting materials,high performance while LEDs were obtained,and high resolution humidity sensor were constructed.This dissertation includes four chapters.In chapter ?,the history of LHP QDs were introduced firstly.Afterwards,the synthesis methods,photochemical and photophysical properties and the stabilization methods of LHP QDs were briefly reviewed.Finally,the optoelectronic and optical sensing applications of LHP QDs were reviewed.In chapter ?,CH3NH3PbBr3 was produced by using grinding method,and their potential in humidity sensing was investigated.The experiments shown that CH3NH3PbBr3 was a good candidate in optical humidity sensing,which exhibit good sensitivity and reversibility towards the change of relative humidity.By coupling with a red emitting organic dye,we fabricated a colorimetric sensor,which enable the humidity sensing by naked eyes.In chapter ?,the stability of lead halide perovskite quantum dots(PQDs)was improved by embedding them in carboxybenzene microcrystals.The resulting needle-shaped mixed microcrystals preserved the strong photoluminescence of the PQDs.Compared with the reported PQDs encapsulated with polystyrene,the carboxybenzene crystals proved to be very robust matrices,protecting the PQDs from moisture and photodegradation.The enhanced stability was attributed to the tight matrix of carboxybenzene microcrystals protecting the PQDs from moisture.This strategy was also very versatile in protecting various QDs,including all-inorganic PQDs and chalcogenide QDs(e.g.CdSe/ZnS QDs and CuInS/ZnS QDs).The method provided a facile and versatile route to protect the PQDs,which may extend their application in solid-state systems with high-color quality requirements such as displays,lasers,light emitting diodes,etc.In chapter IV,we have developed a simple strategy for the fabrication of high luminescent CsPbCl3-Mn NC from CsPbBr3 NC through dual ion exchange with MnCl2,and the CsPbCl3-Mn NC was embedded in KCl.The ion exchange reaction and the embedding process could be achieved simultaneously.The CsPbCl3-Mn@KCl preserve the excellent photoluminescence properties of CsPbBr3 NC,compared with the film fabrication process of CsPbCl3-Mn@polystyrene.The successful doping of Mn in the origin NC were confirmed by inductively coupled plasma mass spectrometry and fluorescence lifetime measurement.The CsPbCl3-Mn@KCl were stable against photo-degradation and thanks to the robust matrix,the resistance to moisture was greatly enhanced.Finally,the CsPbCl3-Mn@KCl was used as color converter in LED applications.