Transistors formed with solution-processed thin films of pentacene

Abstract

Solution-processed pentacene thin films could be prepared directly from pentacene solution without using precursor molecules. The solution-processed pentacene films showed highly oriented and highly crystalline structure. It appeared that large crystal-like platelets grown in the films, and it was assumed that crystalline size of solution-processed films was larger than that of sublimed films determined by in grazing incidence X-ray diffraction method and powder X-ray diffraction method. FETs formed with solution-processed films exhibited good switching properties with the mobility of 0.8cm 2 /Vs and on/off ratio above 10 5 . Maximum carrier mobility above 1cm 2 /Vs was confirmed. The solution-processed film transistors showed lower threshold voltage due to lower carrier density in the films compared with sublimed films. It was confirmed that the solution-processed transistors showed more stable properties for the storage for months than sublimed film transistors. These aspects of transistor performance could be explained by structural difference between solution-processed and sublimed films. Transistors of solution-processed films of pentacene were fabricated by printing technique using a temperature controllable dispenser and the switching operations of isolated transistors were confirmed.