Thiazolothiazole‐Based Quinoidal Compounds for High‐Performance n‐Channel Organic Field‐Effect Transistors with Low‐Cost Metal Electrodes

Abstract

Thiazolothiazole‐based quinoidal molecules B1 and B2 are designed and synthesized. B1 and B2 have low‐lying lowest unoccupied molecular orbital energy levels of −4.47 and −4.41 eV, respectively. In thin films, B1 forms J‐type aggregation while B2 adopts H‐type aggregation. B1 and B2 can react with copper and silver metals and form charge transfer salts. Thin‐film transistor characteristics show both compounds display n‐channel field‐effect behavior, and the Ag and Cu source–drain electrode‐based devices exhibit similar mobility as Au source–drain electrode‐based ones. B1‐based transistors with Au, Cu, and Ag electrodes exhibit electron mobilities of 0.54, 0.45, and 0.39 cm2 V−1 s−1, respectively. The mobility of B2 is 0.061 cm2 V−1 s−1 for Au electrode‐based devices, 0.081 cm2 V−1 s−1 for Cu electrode‐based devices, and 0.09 cm2 V−1 s−1 for Ag electrode‐based devices. The self‐doping layer formed by the reaction of electrodes (Ag, Cu) and organic semiconductors (B1 and B2), at the interface of electrode/organic semiconductor is responsible for the high performance of Ag and Cu electrode‐based devices. All these results demonstrate the introduction of self‐doping layer at electrode/organic semiconductor is a general strategy to fabricate high performance transistors with low cost metals Ag and Cu as source–drain electrodes.

The Syntheses, Characterization and Field Effect Transistor Performance of Thiazole‐Based Dicyanomethylene‐Endcapped Quinoidal Compounds

“…After reacting with QBTzTT8 solution, two new ν(-CN) absorptions are observed for Cu and Ag films, that is 2206 and 2162 cm À 1 for Cu film, and 2197 and 2151 cm À 1 for Ag film. This result is similar as TCNQ-Cu (ν(-CN) absorption at 2200, 2170 cm À 1 ) [38][39] and QBTTzTz10-Cu (ν (-CN) absorption at 2201, 2140 cm À 1 ), [36] indicating the formation of charge transfer complex of QBTzTT8-Cu and QBTzTT8-Ag. In Raman spectra, QBTzTT8 shows ν (À CN) absorption at 2211 cm À 1 and the vibration absorption of conjugated bones at 1000-1500 cm À 1 .…”

“…[37]; [f] the data are taken from ref. [36]; [g] calculated from XRD patterns in Figure S10a. spectrum, QBTzTT8 exhibits a typical ν(-CN) absorption at 2207 cm À 1 (Figure S1, Figure 5g).…”

“…After reacting with Cu and Ag, the ν (À CN) absorption disappears and the vibration absorption of conjugated bones are shifted to larger wavenumber, further demonstrating the charge transfer complex character of QBTzTT8-Cu and QBTzTT8-Ag. [36,39] To investigate the stability of charge transfer complexes, it were exposed in air for three weeks. Then we re-collected the IR and Raman data and found no obvious difference between the data we twice collected, indicating the complexes are stable in air.…”

“…[35] Recently, our group reported a series of thiazolothiazole-based DCMCQCs, one of the representative molecules is QBTTzTz10 (Figure 1). [36] These compounds are air-stable, solution-processable and exhibit high electron mobility. Moreover, they can spontaneously react with Cu and Ag electrodes and form selfdoping charge transfer complex layer at the organic semiconductor/Cu (Ag) interface, and thereby can be used as active In order to systematically study the structure-property relationship of thiazole-based quinoidal compounds, herein thiazolecontained DCMCQCs, QBTzTT8, QBTzTT16 and QBTzTT24 (Figure 1), are synthesized and characterized.…”

Linear, two- and four-armed pyridine-decorated thiazolo[5,4-d]thiazole fluorophores: Synthesis, photophysical study and computational investigation

“…TzTz and its derivatives feature an electron-deficient aromatic moiety that favours rather coplanar conformations in polycyclic systems due to the absence of interactions between ortho H atoms, thus enabling intermolecular interactions. Owing to the ease of their synthesis, which typically is carried out via a double condensation reaction between dithiooxamide and an aromatic aldehyde under oxidative conditions, [11,12] and their appealing electronic properties, [11,13,14] TzTz-based molecular materials with either symmetric or asymmetric architectures have recently started to gain attention in the field of small molecule materials for organic electronics, [15][16][17][18][19][20] as well as bioimaging [21] and chemo-sensing probes [22][23] . In particular, neutral 2,5-bis(hetero)aryl functionalized TzTz derivatives possess short-lived (a few ns) and PLQY in the range of ca.…”