Red-shift of the photoluminescent emission peaks of CdTe quantum dots due to the synergistic interaction with carbon quantum dot mixtures

摘要

Wereporttherelativelylargered-shifteffectobservedindown-shiftingcarbonquantumdots(CQDs)thatisanticipatedtohaveapositiveimpactonthepowerconversionefficiencyofsolarcells.Specifically,withanexcitationwavelengthof390nm,CQDsofdifferentsizes,exhibiteddown-shiftedemissionpeakscenteredaround425nm.However,asolutioncomprisedofamixtureofCQDsofdifferentsizes,wasobservedtohaveanemissionpeakred-shiftedto515nm.Theeffectcouldarisewhenlargercarbonquantumdotscapturethephotonsemittedbytheirsmallercounterpartsfollowedbythesubsequentre-emissionatlongerwavelengths.Furthermore,thered-shifteffectwasalsoobservedinCdTeQDswhenaddedtoasolutionwiththeaforementionedmixtureofCarbonQDs.Thus,whereasasolutionsolelycomprisedofacollectionofCdTeQDsofdifferentsizes,exhibitedadown-shiftedphotoluminescencecenteredaround555nm,thepeakwasobservedtobefurtherred-shiftedto580nmwhencombinedwiththesolutionofCQDsofdifferentsizes.Thequantumdotcharacterizationincludedcrystalstructureanalysisaswellasphotonabsorptionandphotoluminescencewavelengths.Subsequently,thesynthesizedQDsweredispersedinapolymericlayerofpoly-methyl-methacrylate(PMMA)andincorporatedonfunctionalandpreviouslycharacterizedsolarcells,toquantifytheirinfluenceintheelectricalperformanceofthephotovoltaicstructures.WediscussthesynthesisandcharacterizationoftheproducedCarbonandCdTeQDs,aswellastheobservedimprovementinthepowerconversionefficiencyofthefabricatedphotovoltaicdevices...