鈣鈦礦型有機-無機雜化半導體材料的合成及其發(fā)光性質的研究的中期報告

鈣鈦礦型有機—無機雜化半導體材料的合成及其發(fā)光性質的研究的中期報告Abstract:Inthismidtermreport,wepresentthesynthesisandphotoluminescencepropertiesofaseriesofhybridorganic-inorganicperovskitesemiconductorswiththegeneralformulaofABX3,whereAisamonovalentorganiccation,Bisadivalentmetalcation(suchasPb,Sn)andXisahalideanion.X-raydiffractionanalysisindicatesthattheas-synthesizedperovskitesamplesadoptacubiccrystalstructurewithspacegroupPm-3mandlatticeconstantarangingfrom6.3to6.7?.UV-Visabsorptionspectrashowthattheperovskitesampleshavebroadandstrongabsorptioninthevisibleandnear-ultravioletregions,withabsorptionedgerangingfrom400to700nm.Photoluminescencemeasurementsrevealthattheperovskitesamplesexhibitstrongemissionwiththepeakwavelengthrangingfrom550to800nm,suggestingtheirpotentialapplicationsinoptoelectronicdevicessuchaslight-emittingdiodes,solarcellsandlasers.Introduction:Hybridorganic-inorganicperovskitesemiconductorshaveattractedconsiderableattentioninthepastfewyearsduetotheirexceptionaloptoelectronicpropertiesandlowfabricationcost.Theyexhibitlongcarrierlifetimes,highquantumefficienciesandtunableemissioncolors,makingthempromisingcandidatesforvariousoptoelectronicapplications.TheABX3-typeperovskitestructureconsistsofcorner-sharingBX6octahedra,forminganinfinitethree-dimensionalnetwork,andAcationsresidinginthecavitiesbetweenBX6octahedra.TheAcationplaysanimportantroleindeterminingthestability,bandgapandopticalpropertiesoftheperovskitematerial.Inthisproject,weaimtosynthesizeaseriesofA-sitemonovalentorganiccation-basedperovskitematerialsandinvestigatetheirphotoluminescenceproperties.Theorganiccationsusedinthisstudyincludemethylammonium(MA),formamidinium(FA),andphenylethylammonium(PEA).Thedivalentmetalcationusedislead(Pb),andthehalideanionusedisiodide(I).Experimental:Allthechemicalsusedinthisstudywerepurchasedfromcommercialsuppliersandusedwithoutfurtherpurification.Inatypicalsynthesis,0.36gPbI2and0.39goftheorganiccation(MA,FAorPEA)weredissolvedinamixtureofN,N-dimethylformamide(DMF)anddimethylsulfoxide(DMSO)withavolumeratioof8:2.Theresultingsolutionwasstirredat60°Cfor1hourandthencooledtoroomtemperature.Crystalsofperovskitewereobtainedbydrop-castingthesolutionontoaglasssubstrateandleavingittoevaporateatroomtemperature.ResultsandDiscussion:X-raydiffraction(XRD)wasusedtoconfirmthecrystallinestructureandphasepurityofthesynthesizedperovskites.Allthesamplesshowedasharppeakataround14.5°,correspondingtothe(110)planeofthecubicphaseofperovskite(Figure1).ThelatticeconstantawascalculatedfromthediffractionangleusingBragg'slaw.Thevaluesofarangedfrom6.3to6.7?,whichwereingoodagreementwiththereportedvaluesforleadhalideperovskites.UV-Visabsorptionspectrashowedthattheperovskitesampleshadstrongandbroadabsorptioninthevisibleandnear-ultravioletregions,withtheabsorptionedgerangingfrom400to700nm(Figure2).Thebandgapenergy(Eg)ofthesampleswasestimatedfromtheonsetofabsorption,usingtheTaucplotmethod.TheEgvaluesrangedfrom1.41eVto2.12eV,indicatingthatthebandgapoftheperovskitescanbetunedbychangingtheorganiccation.Photoluminescence(PL)measurementswerecarriedouttoinvestigatetheemissionpropertiesofthesynthesizedperovskites.Allthesamplesexhibitedstrongandbroademission,withthepeakwavelengthrangingfrom550to800nm(Figure3).Thebroademissionspectraareattributedtotheformationofself-trappedexcitonsandthepresenceofdefectstates.ThePLquantumyield(PLQY)ofthesampleswasdeterminedusinganintegratingspheresetupandrangedfrom0.12to1.48%,dependingontheorganiccationused.Conclusion:Inconclusion,wehavesynthesizedaseriesofhybridorganic-inorganicperovskitesemiconductorswiththegeneralformulaofABX3,whereAisamonovalentorganiccation,BisleadandXisiodide.Theseperovskitematerialsexhibitedstrongandbroadabsorptioninthevisibleandnear-ultravioletregions,withthebandgapenergyrangingfrom1.41eVto2.12eV.Thesamplesalsoshowedstrongandbroademission,withthepeakwavelengthrangingfrom550to800nm.ThePLQYofthesamplesrangedfrom0.12to1.48%,dependingontheorganiccationused.