We present systematic control of the crystallinity and electrical transport properties of C60 films that are deposited onto pentacene layers, based on simple tuning of the underneath pentacene layer thickness. With increasing the pentacene layer thickness from 0 to 2 monolayers, we observed improvement in crystallinity and grain size of the C60 layer, which led to dramatic enhancement in electron conduction. Also, hole transport in this bilayer structure could be generated when the thickness of the pentacene layer was above one monolayer. The resulting ambipolar transport thin-film transistors yielded electron and hole mobilities as high as 2.8 and 0.3 cm2 V-1 s-1, respectively, and complementary inverters with gain value above 20.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) of Korea funded by the MEST (2009-0076010 and R15-2008-006-01002-0). Use of the Advanced Photon Source was supported by the US Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-06CH11357. Experiments at PAL were supported in part by the Ministry of Education, Science and Technology (MEST) of the Korean Government and Pohang University of Science and Technology (POSTECH).
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)