Ambipolar Transistor Properties of Charge-Transfer Complexes Containing Perylene and Dicyanoquinonediimines

Abstract

To investigate charge polarity of transistors based on donor/acceptor cocrystals, charge-transfer complexes of wide donor molecules such as perylene and pyrene are investigated. As-grown single-crystal transistors are deposited from solutions, which attain perfect reproducibility in comparison with the conventional pasted single-crystal transistors. Perylene complexes of dicyanoquinonediimines (DCNQI) with substituents X = CH 3 , Cl, and Br show holedominant ambipolar characteristics. Owing to the large molecular width, the donor/acceptor orbitals are not orthogonal, and ambipolar transport is realized. In contrast, pyrene works similarly to ordinary acenes, and not only the tetracyanoquinodimethane (TCNQ) complexes but also the DCNQI complex show only electron transport. The existence of the short-axis offset in the molecular overlap is the criterion that transforms electron transport to ambipolar transport.

Charge-transfer complexes of sulfur-rich acceptors derived from birhodanines

“…This is reminiscent of (perylene)(TCNQ). 15,23 The overlapping pattern is basically the same in other perylene complexes (Figs. 3(e), 4(d), 4(f), and 5(d)).…”

“…Perylene and coronene are moderate electron donors, whereas pyrene is a weak electron donor. 14,15 The resulting HOMO-LUMO gaps of the complexes are located in the range of 1.2-1.9 eV.…”

“…Similar variations of rotation angles are observed in the substituted TCNQ complexes. 15,22 The large molecular rotation is, however, not an adequate condition of the short-axis offset; for example, (pyrene)(TCNQ) makes an ordinary stack in spite of the large rotation. 15,22 In the present complex, offset of the molecular center is the origin of the tilted stack ( Fig.…”

“…8,11 This is because the D HOMO and the A LUMO are approximately orthogonal (t ~ 0) due to the horizontal node of the D HOMO. [12][13][14][15] The electron transport is usually mediated by the hybridization of the D next HOMO (HOMO−1), which has the same stripe symmetry as the A LUMO. There are no such "bridge" orbitals to mediate hole transport, and electron-only transport has been universally observed.…”

“…The energy levels are determined by cyclic voltammetry. 2,14,15 The values in the parentheses are from the molecular orbital calculations. (c) Anionic form of SS-R.…”