(TFPP)Eu[Pc(OPh)₈]Eu[Pc(OPh)₈]/CuPc Two-Component Bilayer Heterojunction-Based Organic Transistors with High Ambipolar Performance

Organic thin film transistor (OTFT) devices fabricated by the solution-based QLS technique from a mixed (phthalocyaninato)­(porphyrinato) europium complex (TFPP)­Eu­[Pc­(OPh)₈]­Eu­[Pc­(OPh)₈] exhibit air-stable ambipolar performance with mobilities of 6.0 × 10^–5 cm² V⁻¹ s⁻1 for holes and 1.4 × 10^–4 cm² V^–1 s^–1 for electrons, respectively. In good contrast, the two-component bilayer heterojunction thin film devices constructed by directly growing (TFPP)­Eu­[Pc­(OPh)₈]­Eu­[Pc­(OPh)₈] on vacuum deposited (VCD) CuPc film using solution based QLS method were revealed to show unprecedented ambipolar performance with carrier mobilities of 0.16 cm² V^–1 s^–1 for holes and 0.30 cm² V^–1 s^–1 for electrons. In addition to the intrinsic role of p-type organic semiconductor, the VCD CuPc film on the substrate also acts as a good template that induces significant improvement over the molecular ordering of triple-decker compound in the film. In particular, it results in the change in the aggregation mode of (TFPP)­Eu­[Pc­(OPh)₈]­Eu­[Pc­(OPh)₈] from J-type in the single-layer film to H-type in the bilayer film according to the UV–vis, XRD, and AFM observations