Improve the n-type performance in organic heterojunction transistors by controlling thickness of copper phthalocyanine

N-type C₆₀ thin film transistors with heterojunction were fabricated by introducing copper phthalocyanine (CuPc) modifying layer between polymer dielectrics and C₆₀ semiconductor. Comparing with conventional organic thin film transistors (OTFTs) based on single C₆₀ layer, such devices can not only boost the electron mobility up to 3 times, but also well control threshold voltage V_T and off current I_off by optimizing CuPc thickness. The performance improvement can be attributed to the increase of free electron carriers by the dipole effect at the C₆₀/CuPc interface, and better C₆₀ film quality grown upon CuPc.