Mixed Phases as a Route to Self-Passivation: Effect of π-Stacking Backbone on the Physical and Electrical Properties of Naphthalenediimide Derivatives

Abstract

Solution processable p-and n-type organic semiconductors are candidates for low-cost, large-area, and roll-to-roll printing of inexpensive mass-production electronics. In these organic semiconductors, it is the π-conjugated backbone that plays the major role in chargecarrier transport across the channel. In order to achieve better device performance, it is required to have better packing/crystallinity to minimize defects and avoid deep traps, so that effective transfer of charge carriers can take place in the solid state. Excellent results have been reported by blending crystal-forming organic semiconductors with amorphous polymers that serve as binders or passivating agents. We show that, for some molecular structures and processing conditions, mixtures of stereoisomers can separate and self-arrange into a thin amorphous layer covered by a polycrystalline layer. In this work, we focus on two families of constitutional isomers that differ only in the position of the pyridine groups on the π-skeleton and study the effect of the structure on the physical and electrical properties using absorption spectroscopy, AFM, X-ray, and organic field-effect transistor current−voltage response.

Structural and Magnetic Investigation of Cobalt Valence Tautomeric Complexes with Sulfur-Containing Ligands

“…Co 2 (CO) 8 (with 1−10% of hexanes) and methyl-5-bromothiophene-2-carboxylate (98%) were purchased from Millipore Sigma, 2-cyanothiophene (98%) and 4-bromopyridine hydrochloride (>98%) from Fisher Scientific, and 2-thiopheneboronic acid (>97%) and 3-thiopheneboronic acid (>98%) from VWR. Compounds [Co 4 ( t Bu 2 sq) 8 ] ( t Bu 2 sq = 3,5-di(tert-butyl)-o-semiquinonato), 40 4-(2-thienyl)pyridine (2-tnp), 41 4-(3-thienyl)pyridine (3-tnp), 42 4-(2,2′-bithienyl)pyridine (btnp), 43 3,5-di(2-thienyl)pyridine (dtnp), 44 and 4-(pyridin-4-yl)-1,3-dithiol-2-one (pydto) 45 were synthesized according to the previously published procedures. Ligands methyl-5-(4-pyridinyl)-2-thienylcarboxylate (MeO 2 C-tnp) and 5-(pyridin-4-yl)thiophene-2-carbonitrile (CN-tnp) were synthesized by procedures similar to those reported for methyl-5-(3pyridinyl)-2-thienylcarboxylate 46 and 5-(pyridin-3-yl)thiophene-2-car-bonitrile, 47 respectively, but using 4-pyridinylboronic acid instead of 3-pyridinylboronic acid and 4-bromopyridine hydrochloride instead of 3-bromopyridine hydrochloride, respectively.…”

Recent Progress in Fluorinated Dielectric‐Based Organic Field‐Effect Transistors and Applications

“…[ 61,62 ] However, many other factors are known to carrier trapping agents (e.g., the crystallinity of semiconductor layers, interface conditions between atmosphere and semiconductor layers, etc.). [ 63 ] With the efforts of interface optimization, charge‐carrier mobilities of transistors ( Table 1 ) are comparable to those of hydrogenated amorphous silicon (α‐Si: H, ≈0.5–1.0 cm 2 V −1 s −1[ 64 ] ), and some functionalized devices based on fluorinated dielectrics such as flexible sensors were successfully fabricated as well. [ 65–68 ] We will clarify their modulation strategies in different functional devices through the influence of different fluorinated dielectric layers on charge transfer, interface modulation, and charge injection in OFETs.…”