Numerical Study on Recombination Efficiency at 4,4$'$-Bis(2,2$'$-diphenylvinyl)-1,1$'$-spirobiphenyl/Tris(8-quinolinolato)aluminium Interface in Organic Light Emitting Diodes

In this paper, we report our numerical study on the electrical and optical properties of the organic light emitting diodes (OLEDs) devices with n-doped layer, which is inserted for the purpose of reducing the interface barrier height between the cathode and the electron transport layer (ETL). We performed finite element method (FEM) simulation on OLEDs in order to understand the transport behavior of carriers, recombination kinetics, and emission property. Our model includes Poisson's equation, continuity equation to account for behavior of electrons and holes and exciton continuity/transfer equation to account for recombination of carriers. We employ the multilayer structure which consists of indium tin oxide (ITO); 2,2$'$,7,7$'$-tetrakis( N , N -diphenylamine)-9,9$'$-spirobi-fluorene (S-TAD); 4,4$'$-bis(2,2$'$-diphenylvinyl)-1,1$'$-spirobiphenyl (S-DPVBi); tris(8-quinolinolato)aluminium (Alq 3 ); calcium (Ca).