Organic semiconductors provide a wealth of interesting properties like tailor made
electrical characteristics, cost effective large area fabrication and mechanical flexibility
which can be difficult to achieve with crystalline inorganic semiconductors. However,
their advance into applications such as logic circuits is hindered by the limited availability
of high performance air-stable n-type materials, which limits organics to unipolar circuits.
This thesis explores three different routes to improve the performance of n-type organic
semiconductors. Firstly a novel air-stable small molecule with mobilities of up to
0.6 cm2/Vs in TFTs is presented. We blend the small molecule with a polymer to
improve the thin film smoothness and homogeneity. In combination with an established
p-type small molecule:polymer blend semiconductor we demonstrate an air-stable, solution
processed, complementary inverter with gains above 5. Secondly we use doping to enhance
the properties of Fullerene semiconductors. The efficiency of the doping process is found
to depend strongly on the Fullerene derivative used as matrix material, but where
it is effective, we see an increase in charge carrier mobility by the filling of shallow
trap states and enhanced bias stress stability. Thirdly we investigate a new patterning
process called adhesion lithography for metal electrodes, which is compatible with high
throughput fabrication. We use the process to manufacture asymmetric electrodes
with a distance below 15 nm. Taking advantage of the short distance and the small
parasitic capacitance of the structure we fabricate Schottky diodes based on Fullerenes
with operating frequencies exceeding 20 MHz. These diodes can be used in wireless
communication or energy harvesting systems. The findings may help to develop new
materials and processes for the next generation of organic semiconductors.