Photoinduced magnetoconductance response of N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine-based diodes: Sign inversion by controlling carrier extraction

Abstract

We explore the magnetoconductance (MC) response of N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine-based single-layer devices. The MC effect can be observed only if the device is irradiated with light, for measurement voltages |V|<5V. A positive MC with a non-Lorentzian line shape is obtained under forward bias. Under reverse bias, however, the MC shows both positive and negative components, forming a “W” shape with dips at about ±100mT. The sign of the MC under reverse bias can be changed by controlling the carrier extraction from the anode/organic interface. We suggest that the positive MC is caused by triplet–polaron interaction and the negative MC by bipolaron formation.