Organic Light-emitting Diodes Based On High Exciton Utilizing Efficiency Host Materials

The prospect of using organic materials for OLEDs has flourished for decades due to the enormous potential of OLEDs for smart phones,flatpanel displays,and solid-light emitting applications.High exciton utilizing efficiency materials have continued to attract interests.However,high exciton utilizing efficiency materials usually have low photoluminescence(PL)efficiency.In this thesis,we mainly study on OLED using high exciton utilizing efficiency materials as host.(1)Firstly,we optimized the OLED device structure based on a reported TADF material CN-TPA.Secondly,we also fabricated a green TADF OLED using a new material CN-PhO,which exhibited a low turn-on voltage of 2.8 V,a high current efficiency of 29 cd/A and a maximum EQE of 10.60%.Thirdly,we used CN-PhO as sensitizing host for conventional fluorescent DCJTB that realize external quantum efficiencies as high as 10%.(2)A blue light-emitting exciplex system based on two common hole and electron transport material(m-MTDATA and TmPyPb)has been made.Meanwhile,the exciplex also has a lifetime of 7 us,which demonstrate its TADF effect.Here we demonstrate an OLED with very high efficiencies,produced by using m-MTDATA:TmPyPb exciplex system as an exciplex-forming co-host.We doped MoO3 with m-MTDATA as the HTL,which greatly improved the efficiency.The OLED exhibited a low turn-on voltage of 2.3 V,a high current efficiency of 43 cd/A and a maximum EQE of 12%.(3)Firstly,we optimized the OLED device structure based on a reported HLCT material TPMCN.Secondly,we used mCP and TPMCN(sensitizing host)as host to sensitize conventional fluorescent material(C545T),which realized an external quantum efficiencies as high as 5.2%,a low turn-on voltage of 3 V,a high current efficiency of 19 cd/A.The maximum of EQE has broken the limitation of conventional fluorescent material(5%).