Fabrication And Performance Of AMOLED Based On Carbon Nanotube Thin Film Transistors

Organic light-emitting diodes(OLEDs)are regarded as the next generation of important display technology due to self-luminescence,good color saturation,small device thickness,and flexible fabrication compared with conventional display technologies.The active matrix organic light-emitting(AMOLED)display technology is the mainstream direction of future display technology development,which can meet the diversified needs of future information display forms.At the same time,it also puts forward higher requirements for the electrical characteristics of driving circuit channel materials.Carbon nanotubes(CNTs),as a new kind of nano-materials,are expected to be used in flexible electronic devices due to their excellent electrical,mechanical and optical properties.In recent years,researchers have used CNTs as channel materials for transistors,conducting research in high-performance integrated circuits,sensors,memory,and electronic skin,and have achieved a series of phased results.Among them,the application of flexible display has attracted great attention,but there is still a certain gap between the research level and the actual application requirements.The main problems of CNTs-based AMOLED driving circuits include:(a)The integration degree of the circuit is not high.(b)The surface roughness of the sample caused by the device preparation process is too large and the piercing of the OLED material results in a low yield.(c)The inhomogeneous film formation of carbon nanotube films,resulting in inconsistency of the circuit performance of each pixel and affect the luminous uniformity.In this paper,we proposed a new sample substrate treatment method,which effectively reduces the surface roughness of the driving circuit.And by using high purity semiconductor carbon nanotube dispersions(>99%),very uniform carbon nanotube films were prepared by solution method as the channel material of transistors.A highly integrated AMOLED driving circuit with 64×64 pixel is designed and fabricated on the flexible substrate.The whole circuit consists of more than 8000 transistors,showing excellent uniformity of carbon nanotube films.The average on/off ratio is up to 107,the average carrier mobility is up to 15 cm2V-1s-1,and the electrical performance of the circuit has no obvious changed when the bending strain is 0.4%,showing good current drive capability and stability.By exploring the top-emitting structure of the OLED,the appropriate material and thickness parameters were determined.And achieve a very uniform illuminating effect and a yield of up to 99.93%in the AMOLED lighting test.The results of this study represent the best level in the world in the research of flexible AMOLED devices based on CNTs,and illustrate the broad application prospects of driving backplane based on carbon nanotube thin film transistors in the next generation of large-area flexible display.