Cyanation: Providing a Three‐in‐One Advantage for the Design of n‐Type Organic Field‐Effect Transistors

Abstract

The theoretical work presented here demonstrates that, when substitution takes place at appropriate positions, cyanation could be a useful tool for reducing the internal reorganization energy of molecules. A molecular-orbital-based explanation is given for this fundamentally important phenomenon. Some of the cyanated pentacene derivatives (nCN-PENT-n) not only have internal reorganization energies for electron transfer (lambda(-)) smaller than that of pentacene, but the lambda(-) values are even of the same magnitude as the internal reorganization energy for hole transfer (lambda(+)) of pentacene, a small value that few organic compounds have surpassed. In addition, cyanation raises the electron affinity of the parent compound and may afford good electronic couplings between neighboring molecules, because of its ability in promoting pi-stacking. For the design of high performance n-Type Organic field-effect transistors, high electron affinities, large intermolecular electronic couplings, and small reorganization energies are necessary. Cyanation may help in all three aspects. Two cyanated trialkylsilylethynyl pentacene derivatives with known pi-stacking structures are predicted to provide reasonably small internal reorganization energies, large electronic couplings, and high electron affinities. They have the potential to outperform N-fluoroalkylated dicyanoperylene-3,4:9,10-bis(dicarboximides) (PDI-FCN(2)) in terms of electron mobility.

Torsional angle dependence and switching of inner sphere reorganisation energies for electron and hole transfer processes involving phenyl substituted diketopyrrolopyrroles; a density functional study

“…The B3LYP results agree within 1 kJ mol -1 of the published values (often employing larger basis sets). [38,54,55] Turning to the DPPs, once again we find that λ e < λ h for all of the DPPs in Table 3 irrespective of H/Me and P/T group substitution. This relative ordering of λ e < λ h at low θ values would seem to be an inherent property of the DPP core motif itself.…”

BODIPY derivatives as n-type organic semiconductors: Isomer effect on carrier mobility

“…It's easy to find that k À of 1 and 2 are both smaller than k + . High reorganization energy is unfavorable for higher carrier mobilities [26,69,70].…”

“…The development of single-crystal organic field effect transistors (SCOFETs) makes it possible to explore intrinsic properties of these materials [9][10][11]. p-Type organic semiconductors such as pentacene, rubrene and derivatives of them have been investigated widely [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The recently improved theoretical understandings of organic semiconductors have even addressed the design rule of organics with high hole mobilities [28][29][30][31].…”

Bis(arylene-ethynylene)-s-tetrazines: A Promising Family of n-Type Organic Semiconductors?

“…Even so, E LUMO values calculated for (ArCC) 2 Tz, excepting only (PhCC) 2 Tz, are comparable to those estimated for other aryl-s-tetrazine derivatives. In this sense, the presence of halogen atoms and especially cyanide groups in the (ArCC) 2 Tz compounds significantly lowers E LUMO with respect to (PhCC) 2 Tz which should bring on a more efficient charge injection 38,49,52,83 and could also help the environmental stability of the material. 52,84 Interestingly, E LUMO is decreased by 0.4 -0.5 eV with respect to (PhCC) 2 Tz due to the were calculated for all the studied compounds with respect to some common electrodes used for electron injection, i.e.…”