Improved Performance of Fluorinated Copper Phthalocyanine Thin Film Transistors UsingPara-hexaphenyl as the Inducing Layer

We demonstrate n-type organic thin film transistors(OTFTs)employing copper hexadecafluorophthalocyanine(CuPcF16)as the active layer and para-hexaphenyl(p-6p)as the inducing layer.Compared with the CuPcF16-based OTFTs without the𝑝p-6p inducing layer,the performance of the CuPcF16/𝑝p-6p OTFTs is greatly improved.The charge carrier field-effect mobilityμ,on-off current ratio𝐼Ⅰon/Ⅰoff and threshold voltage𝑉VT of the CuPcF16/p-6p OTFTs are 0.07 cm^(2)/V・s,1.61×105 and 6.28 V,respectively,approaching the level of a single crystal device.The improved performance is attributed to the introduction of𝑝p-6p to form a highly oriented and continuous film of CuPcF16 with the molecularπ–πstack direction parallel to the substrate.

Significant Improvement of Organic Thin-Film Transistor Mobility Utilizing an Organic Heterojunction Buffer Layer

High-mobility vanadyl phthalocyanine(VOPc)/5,5"'−bis(4-fluorophenyl)-2,2':5',2":5",2"'−quaterthiophene(F2-P4T)thin-film transistors are demonstrated by employing a copper hexadecafluorophthalocyanine(F16CuPc)/copper phthalocyanine(CuPc)heterojunction unit,which are fabricated at different substrate temperatures,as a buffer layer.The highest mobility of 4.08 cm^(2)/Vs is achieved using a F16CuPc/CuPc organic heterojunction buffer layer fabricated at high substrate temperature.Compared with the random small grain-like morphology of the room-temperature buffer layer,the high-temperature organic heterojunction presents a large-sized fiber-like film morphology,resulting in an enhanced conductivity.Thus the contact resistance of the transistor is significantly reduced and an obvious improvement in device mobility is obtained.