Comparison of electrical characteristics for p-type and n-type organic thin film transistors using copper phthalocyanine

The p-type and n-type organic thin film transistors (OTFTs) were fabricated in the same experimental conditions by using hexadecahydro copper phthalocyanine (H16CuPc) and hexadecafluoro copper phthalocynine (F16CuPc) molecules, respectively. The mobilities of H16CuPc and F16CuPc-based OTFT devices in saturation region were measured to be similar to 1.22 x 10(-3) cm(2)/V s and similar to 1.04 x 10(-3) cm(2)/V s, respectively. The temperature dependence of the mobility and activation energy (E-a) for both OTFTs were measured in saturation and linear regions of the drain-source current. We found that the E-a of the F16CuPc-based OTFTs was lower than that of H16CuPc-based ones. The gate voltage (V-g) dependence of the field-effect mobility measured in linear region for the F16CuPc-based OTFTs was more stable, i.e., weaker variation of the field-effect mobility with increasing V-g, than that of the H16CuPc-based ones. The high electron affinity of the hexadecafluorine (F-16) in CuPc contributed to the effective electron accumulation in the active channel. (c) 2008 Elsevier B.V. All rights reserved.