The dark current density in donor/acceptor organic planar heterostructure devices at a given forward voltage bias can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of interfacial exciplex states. If the exciplex recombination rate limits current flow, an insulating interface layer decreases the dark current. However, if the exciplex formation rate limits the current, an insulating interface layer may increase the dark current. We present a device model to describe this behavior, and we discuss relevant experimental data.
Bibliographical noteFunding Information:
We thank B.K. Crone and S.A. Crooker for valuable comments. The work at LANL is supported by the Los Alamos LDRD program. S.Y. thanks the financial support by China’s Visiting Scholarship , the Excellent Youth and Middle Age Scientists Fund of Shandong Province (No. BS2012CL025 ) and the Independent Innovation Foundation of Shandong University (No. 2012TS022 ).
- Current-voltage characteristics
- Insulating spacer layer
- Organic heterostructure