Research On Performance Of Organic Light-emitting Diodes And Organic Solar Cells By Phosphorescent Dye Doping

In this paper, organic light-emitting diodes（OLEDs） with co-evaporated Alq₃:30wt%Cs₂CO₃cathode or phosphorescent dye doping were investigated. Moreover,organic solar cells with phosphorescent dye doping were also studied.The co-evaporating film of Alq₃:30wt%Cs₂CO₃serves as an electron injectionlayer in OLEDs, which significantly enhances the device luminance and efficiencycompared to the ultra-thin Cs₂CO₃injection layer. The influence of this layer on theperformance of organic light-emitting diodes was investigated. A maximum currentefficiency of6.5cd/A（3.1cd/A for Cs₂CO₃/Al） is obtained for30wt%Cs₂CO₃dopingconcentration device. It is proposed that this improved efficiency is related to thegreatly enhanced electron injection at the Alq₃:30wt%Cs₂CO₃/Al cathode interfaceand efficient electron transport in the bulk of the Alq₃:30wt%Cs₂CO₃layer. Theresults using atomic force microscopy show that the insertion of Alq₃:30wt%Cs₂CO₃layer, the roughness of Alq₃surface decreases, which is favorable to improve thedevice luminance and increase the device lifetime.Doping phosphorescent dye PtOEP into the polymer donor MEH-PPV for planarbilayer organic solar cells based on MEH-PPV/C₇₀heterojunction was researched.The short-circuit current （Jsc）, open-circuit voltage （Voc） and power conversionefficiency （PCE） of organic solar cells increase from4.51mA/cm²,0.49V and0.81%for undoped cells to5.86mA/cm²,0.53V and1.15%for5wt%PtOEP doped cells,respectively. The enhancement of device performance is related to the effectivegeneration and dissociation of triplet excitons. The short-circuit current is slightlyincreased and the other parameters aren’t increased for5wt%Ir（piq）2（acac） dopedcells.Solution-processable devices with CBP doped phosphorescent dye Ir（CzBPPF）2（PZ） host were studied. A maximum luminance of1104cd/m2is obtainedfor2wt%Ir（CzBPPF）2（PZ） doping concentration device. The maximum luminancehas been increased by87%compared to the device without PVK as the hole transportlayer. The energy transfer between host and guest is investigated. The factors thatinfluence the performance of phosphoresence OLEDs are proposed.