Towards implementation of logic circuits based on intrinsically reconfigurable organic transistors

Unraveling the Microstructure of Molecularly Doped Poly(3-hexylthiophene) by Thermally Induced Dedoping

“…Organic semiconductors (OSCs) increasingly complement their inorganic counterparts in electronics and will likely become a vital part in future applications. − In particular, organic light-emitting diodes based on OSCs are already employed in displays of today’s flagship mobile phones , and their high potential for low cost; large-area production on flexible substrates entails novel possibilities for implementing OSC-based electronics. , In essentially all applications, the p-/n-doping of OSCs using molecular dopants (i.e., strong electron donors or acceptors) plays a key role because it allows both increasing the electrical conductivity in transport layers and tailoring the interfacial energetics to application-specific demands. , During the past decade, significant research efforts have been directed not only to exploit the potential of doped OSCs in (opto-)­electronic applications but also to understand the fundamental processes at work. − Two mechanisms underlying the transfer of charge upon doping OSCs have been identified: (i) the immediate formation of ion pairs (IPAs) through integer charge transfer with an electron on the p-dopant and a (mobile) hole in the OSC matrix and (ii) the formation of ground-state charge-transfer complexes (CPXs) through intermolecular frontier orbital hybridization and fractional charge transfer. Although CPX formation has been reported for numerous small-molecular OSCs doped with the prototypical molecular acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetra­cyanoquino­dimethane (F4TCNQ), − IPA formation appears to occur predominantly for conjugated polymers (CPs).…”

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We exploited the thermal annealing of poly(3hexylthiophene) (P3HT) molecularly p-doped with the strong electron acceptor 2, 3,5,7,8, as a tool for tuning the doping concentration as a quasi singular parameter. Via directed dopant desorption, we could unravel the complex microstructure of this semicrystalline system, leading to a detailed growth model solely based on complementary experimental evidence from scattering and spectroscopic techniques.

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