Electrode and dielectric layer interface device engineering study using furan flanked diketopyrrolopyrrole-dithienothiophene polymer based organic transistors

Dithieno[3,2-b:2',3'-d]thiophene (DTT): an emerging heterocyclic building block for future organic electronic materials & functional supramolecular chemistry

Heterocyclic compounds being potent biochemical materials are ubiquitous molecules in our life. Amongst, the five membered aromatic ring systems, thiophene has emerged as a remarkable entity in organic electronics owing to its (i) high resonance energy, (ii) more electrophilic reactivity than benzene, (iii) high π-electron density, (iv) planar structure and, (v) presence of vacant d-orbital in addition to the presence of loosely bind lone-pairs of electrons on sulfur atoms. In recent past, thiophene-fused molecule namely, dithienothiophene (DTT) has attracted a tremendous attention of the researchers worldwide due to their potential applicability in organic electronics such as in solar cells, electrochromic devices (ECDs), organic field effect transistors (OFETs), organic limiting diodes (OLEDs), fluorescent probes, redox switching and so forth because of their (i) higher charge mobility, (ii) extended π-conjugation, and (iii) better tuning of band gaps, etc. In this particular review article, we envisioned to report the recent advancements made on the DTT-based architectures not only because of the potential applicability of this valuable scaffold in organic electronic but also to motivate the young researchers worldwide to look for the challenging opportunities related to this privileged building block in both material sciences and functional supramolecular chemistry.

The Quinonoid Zwitterion Interlayer for the Improvement of Charge Carrier Mobility in Organic Field-Effect Transistors

The interface between the semiconductor and the dielectric layer plays a crucial role in organic field-effect transistors (OFETs) because it is at the interface that charge carriers are accumulated and transported. In this study, four zwitterionic benzoquinonemonoimine dyes featuring alkyl and aryl N-substituents were used to cover the dielectric layers in OFET structures. The best interlayer material, containing aliphatic side groups, increased charge carrier mobility in the measured systems. This improvement can be explained by the reduction in the number of the charge carrier trapping sites at the dielectric active layer interface from 10¹⁴ eV⁻¹ cm⁻² to 2 × 10¹³ eV⁻¹ cm⁻². The density of the traps was one order of magnitude lower compared to the unmodified transistors. This resulted in an increase in charge carrier mobility in the tested poly [2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno [3,2-b]thiophene)] (DPPDTT)-based transistors to 5.4 × 10⁻¹ cm² V⁻¹ s⁻¹.