Device performance and carrier dynamics in blue mixing host organic light-emitting devices

摘要

In this paper, we study device performance and carrier dynamics of an organic light-emitting device (OLED) with an emitting layer (EML) based on a mixed-host (MH) structure. Such a structure is composed of two different host and one dopant materials. It exhibits longer operation lifetime as compared with a conventional heterojunction (HJ) device. In such a MH layer structure, carrier transport characteristic is modified and emission zone position is changed. Energy transfer from the two hosts to one dopant is studied by EL, PL and TRPL measurements. We observe spectrum shift from the EL measurement under different current injection. Incompletely energy transfer from NPB to DPAVBi is shown in cw PL measurement. Time constant at different probe wavelengths with different mixing concentration suggests that different energy transfer in such a MH structure.