Mobility dependence on the conducting channel dimension of organic field-effect transistors based on single-crystalline nanoribbons

Abstract

Understanding the relationship between the conducting channel and device property in organic single-crystalline transistors is important for the valuation of materials and construction of high performance devices. In order to achieve this target, mobility dependence on the channel dimension of organic single-crystalline transistors was investigated by using nanoribbon transistor arrays of copper hexadecafluorophthalocyanine (F₁₆CuPc) and rubrene. Single-crystalline nanoribbons of F₁₆CuPc and rubrene were produced by a physical vapor transport technique. A friction-printing method was developed to mass-produce transistor arrays. High performance devices were obtained with mobility of F₁₆CuPc up to 0.6 cm² V⁻¹s⁻¹ and rubrene of 24.5 cm² V⁻¹s⁻¹, which were among the OFETs with the highest device performance. Mobility distributions of the devices based on different sized crystals were summarized and analysed carefully. It was demonstrated that the mobility of the devices decreased exponentially with the widening and thickening of the crystals, but increased linearly with the increasing of the conducting channel at 3–15 μm. The mobility dependences on the channel dimension were mainly assigned to the change of the transistor resistances which were series connected in a transistor circuit, influencing the current transport between source and drain.