Design And Optimization Of Novel Organic Light-emitting Diodes

The research of materials in organic light-emitting diodes?OLEDs?has made great achievements,but in terms of the design ideas and fabrication technologies are still scarce.In this work,we focused on the design ideas and fabrication technologies of OLEDs.Based on blue fluorescent and green phosphorescent complex,a series of OLEDs with single light-emitting layer?EML?,double EMLs and sensitized EML?with transition metal complexes as sensitizer?were designed and fabricated,the luminescent process was also investigated.We have designed and fabricated the highly efficient blue fluorescent and green phosphorescent devices by selecting BCzVBi and?tfmppy?2Ir?tpip?as emitters,respectively.High performance blue and green electroluminescent?EL?devices with maximum forward-viewing external quantum efficiency?EQE?,current efficiency,power efficiency and brightness up to 8.0%/25.3%,11.99/102.29 cd/A,10.91/88.67 lm/W and 36060/96268 cd/m2,respectively,were realized by optimizing the doping concentration and thickness of each functional layer in sequence.BCz VBi doped TcTa and 26 DCzPPy layers function as predominant and supplementary EMLs,respectively,in blue fluorescent OLEDs.The sensitizer molecules were found to function as deeper electron trappers,which helps to balance the carriers' distribution in the green phosphorescent OLEDs.According to the study of the PL spectra and triplet energies of materials,we found the sensitizer moleculesdon't function as the ladder of energy transfer from 26 DCzPPy to?tfmppy?₂ Ir?tpip?molecules.