Influence of emissive layer thickness on electrical characteristics of polyfluorene copolymer based polymer light emitting diodes

摘要

Polymerlightemittingdiodes(PLEDs)withadeviceconfigurationofITO/PEDOT:PSS/PFONPN01[Poly[2,7-(9,9'-dioctylfluorene)-co-N-phenyl-1,8-naphthalimide(99:01)]/LiF/Alhavebeenfabricatedbyvaryingtheemissivelayer(EML)thickness(40/65/80/130nm)andtheinfluenceofEMLthicknessontheelectricalcharacteristicsofPLEDhasbeenstudied.PLEDcanbemodelledasasimplecombinationofresistorsandcapacitors.TheimpedancespectroscopyanalysisshowedthatthedeviceswithdifferentEMLthicknesshaddifferentvaluesofparallelresistance(RP)andtheparallelcapacitance(CP).TheimpedanceofthedevicesisfoundtoincreasewithincreasingEMLthicknessresultinginanincreaseinthedrivingvoltage.Thedevicewithanemissivelayerthicknessof80nm,spincoatedfromasolutionofconcentration15mg/mLisfoundtogivethebestdeviceperformancewithamaximumbrightnessvalueof5226cd/m2...