Conductivity Enhancement in Organic Electronics by Delta Doping

The effects of delta doping in organic materials were investigated by incorporating periodic 0.5-nm MoO
₃
layers into a Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) thin film. Secondary ion mass spectrometry revealed the transient diffusion of MoO
₃
into the underlying TCTA, resulting in a stable delta doping profile. Delta-doped hole-only devices exhibited greatly enhanced current conduction along and perpendicular to the film plane compared with a uniformly doped device, and had a turn-on voltage as low as 1 V. The enhanced conductivity is attributed to free hole accumulation in potential wells formed in the delta-doped regions as a result of doping-induced energy level shifts. This unique doping strategy may open new perspectives for developing high-transconductance organic transport devices.