Mn-doped All-inorganic Perovskite Quantum Dots And The Applications In White LED

All-inorganic CsPbX3(X=Cl,Br,or I)perovskite quantum dots(PQDs)have attracted great attention in the field of light emitting diodes(LEDs),solar cells,laser and so forth because of their superior optical properties including narrow full width at half-maximum(FWHM,down to 15 nm),high photoluminescence quantum yield(PLQY,up to 90%)and tunable full spectral visible luminescence(400-780 nm).Unfortunately,the toxicity of Pb2+ions in PQDs severely limits their practical application.As far as we know,the superior optical properties of PQDs are mainly attributed to[PbX6]4-octahedra,the partial substitution of Pb2+ by Mn2+ is also explored.Mn2+ orange emission assigned to Mn2+:4T1?6A1 transition was detected and energy transfer from excitons to Mn2+ activators was evidenced.Impressively,besides the reduced usage of the toxic lead element,Mn2+ dopants were found to effectively improve the structure stability of perovskite PQDs benefited from the high formation energy of Mn2+:CsPbX3 relative to pure CsPbX3.Herein,the optical properties,microstructure,stability and applications of Mn doped PQDs were studied.The main works are as follows:Mn2+ Doped PQDs with dual-color prepared by hot injection without concern for an adverse reabsorption effect caused by mixing of multiple-color.We address these issues with high-content Mn2+ doped CsPbCl3 PQDs that can yield blue-excitable orange Mn2+ emission by Cl-to-Br anion exchange.Silica-coating was applied to improve air stability of PQDs and these coating PQDs are applied to white LEDs.Mn-doped CsPbCl3 nanocrystals are successfully prepared via a innovative solvothermal reaction.Importantly,it is demonstrated that Mn-doped CsPbCl3b NCs synthesized by the solvothermal method have better stability than those prepared by traditional hot injection.To finely adjust the bandgap of CsPbCl3 NCs,Cl-to-Br anion exchange is used to fabricate Mn-doped CsPb(Cl/Br)3 NCs with tunable multi-color luminescence.Finally,the as-prepared Mn-doped CsPb(Cl/Br)3 products are demonstrated to be applicable for white light-emitting diodes and accurate temperature sensing.We introduce room-temperature reverse synthesis of CsPbxMn1-xCl3 PDQs from CsMnCl3 precursor nanocrystals through Mn2+?Pb2+ cation exchange.Two-step phase transformation processes from hexagonal CsMnCl3 to rhombohedral Cs4PbxMn1-xCl6 and finally to cubic CsPbxMn1-xCl3 are evidenced.Mn2+ broad band luminescence is not detected for theCs4PbxMn1-xCl6 product,but it is intense for the CsPbxMn1-xCl3 sample owing to efficient energy transfer from CsPbCl3 to Mn2+ according spectra.Moreover,it is found that the introduction of Br into the reaction system will prohibit the complete phase transformation.