Organic semiconductors can be prepared as molecular single crystals by vacuum
evaporation. This brings closer the coupling of the π systems and increases the band
Long chain organic semiconductors are usually polymers that have π bonds that
are delocalized along the chain to form a one-dimensional system resulting in a 1D-band
structure that has considerable band width. The transport properties of such polymers are
usually determined by defects in the 1D-chains or by hopping from chain to chain.
Polymer organic semiconductors are usually deposited in wet processes, like spin coating
or doctor blading.
Delocalization in polymer semiconductor is accomplished by forming a conjugated
backbone of continuous overlapping orbitals. This includes alternating single and double
carbon-carbon bonds, which leaves a continuous path of overlapping p orbitals (figure 4).