Threshold shift by polymeric cover layer containing phthalocyanine pigment on printed CNT transistors

Possibility of controlling the threshold voltage of printed carbon nanotube (CNT) transistor is shown. Printed CNT transistors are fabricated by mask-less printing and coating process on plastic film, and polymeric cover layer which contains phthalocyanine pigment is printed on the CNT channel. Forming the cover layer, threshold voltage shifts by 30 V to negative direction. It successfully reduces drain current when gate voltage is turned off, and an effective on/off ratio is increased. This device also shows photoresponsivity. Photo response device with simple structure is also much attractive for the printed electronics applications.