Amorphous Solid Simulation and Trial Fabrication of the Organic Field-Effect Transistor of Tetrathienonaphthalenes Prepared by Using Microflow Photochemical Reactions: A Theoretical Calculation-Inspired Investigation

The
p-type organic semiconductor (OSC) material tetrathieno­[2,3-a:3′,2′-c:2″,3″-f:3‴,2‴-h]­naphthalene (2TTN)
and its alkyl-substituted derivatives Cn-2TTNs (n = 6, 8, and 10) have been developed based
on the results of theoretical calculation-inspired investigation.
A hole mobility for amorphous Cn-2TTNs
(10–2–10–3 cm2 V–1 s–1) was accurately predicted
by using a novel statistical method in which the geometric mean of
the mobilities for many individual small molecular flocks in an amorphous
solid was obtained by using molecular mechanical molecular dynamics
simulations and quantum chemical calculations. The simulation also
suggests that upon increasing the length of alkyl chains in Cn-2TTNs the mobilities become smaller as a
consequence of a decrease in transfer integral values. Cn-2TTNs are synthesized in a microflow reactor through
photoreactions of the corresponding precursors. Cn-2TTNs are then utilized in the fabrication of organic field-effect
transistors (OFETs). Although spin-coated thin films of Cn-2TTNs are crystalline, the hole mobilities (10–2–10–3 cm2 V–1 s–1) of trial OFETs decrease upon
elongation of the alkyl chains. This finding parallels the results
of theoretical simulation. The simulation method for amorphous solids
developed in this effort should become a useful tool in studies aimed
at designing new OSC materials.