2D molecular crystal templated organic p-n heterojunctions for high-performance ambipolar organic field-effect transistors

Bilayer p-n heterojunctions are promising structures to achieve high-performance ambipolar organic field-effect transistors (aOFETs). However, the performance of aOFETs based on polycrystalline bilayer p-n heterojunctions was substantially reduced compared with that of their unipolar devices due to the unavoidable interlayer mixing in bilayer heterojunctions fabricated by conventional methods such as two-step spin-coating or vacuum-deposition. Herein, the interlayer mixing problem was reduced by 2D molecular crystal (2DMC) templated growth of high-quality bilayer p-n heterojunctions. Due to the excellent wettability of the 2DMC template for organic semiconductors, the grain size of the upper layer was substantially enlarged. Moreover, the atomically flat surface and the long-range order of the 2DMC template reduced the common interlayer mixing problem. As a result, the mobility of copper hexadecafluorophthalocyanine (F16CuPc) increased over one order of magnitude compared with that of their unipolar devices. Actually, the electron mobility of 0.56 cm(2) V-1 s(-1) was the highest among both ambipolar OFETs and unipolar OFETs adopting F16CuPc as the n-type semiconductor.

Automated summary

Growing high-quality bilayer p-n heterojunctions using 2D molecular crystal templates can reduce interlayer mixing issues and enhance the performance of aOFETs.