Importance of domain purity in semi‐conducting polymer/insulating polymer blends transistors

Abstract

Printed electronics is a rapidly developing field of research which covers any electronic devices or circuits that can be processed using direct printing techniques. Among those printing techniques, inkjet printing is a technique of increasing interest for organic field-effect transistors (FETs) due to its fully data driven and direct patterning. In this work, the morphology of semi-conducting polymer/insulating polymer blends from inkjet printing and their FET properties have been investigated. We attempted to optimize the morphology of the blends by the addition of a co-solvent to the blend solution prior to film deposition. By varying the boiling temperature of the co-solvent, blend films are fabricated with varying domain purity and different degree of semi-conducting polymer ordering. The morphologies of all the as-cast samples from inkjet printing and subsequently thermally annealed samples are characterized by grazing incidence wide angle x-ray scattering and small angle neutron scattering. The results indicate that the sample where a low boiling temperature cosolvent is used exhibits a lower degree of semi-conducting polymer ordering and less pure domains, resulting in a decrease of hole mobility. The morphologies that are formed when high boiling temperature co-solvent is used, however, give a higher degree of semi-conducting polymer ordering along with higher domain purity, significantly improving hole mobility up to 1.44 cm 2 V 21 s 21 at V DS 5 40 V. More importantly, with thermal annealing, all the samples exhibit similar semi-conducting polymer ordering and domain sizes while the domain purity significantly varies. This work is a unique example that demonstrates the importance of domain purity in the optimization of morphology and FET performance, which is previous unavailable. It also provides a novel process that can efficiently control the morphology of semi-conducting polymer/insulating polymer mixtures during deposition to maximize FET performance from inkjet printing.

High Performance Flexible Nonvolatile Memory Based on Vertical Organic Thin Film Transistor

“…High molecular weight π‐extended organic p‐type semiconductor copolymer poly[2,5‐bis(alkyl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐alt‐5,5′‐ di(thiophen‐2‐yl)‐2,2′‐(E)‐2‐(2‐(thiophen‐2‐yl)vinyl)‐thiophene] (PDVT‐8) ( M w = 50 K, polymer dispersity index (PDI) = 2.4) was obtained from 1‐Materials, which was dissolved in chloroform (10 mg mL −1 ) . Poly(4‐vinylphenol) (PVP) ( M w = 25 000), 4,4′‐(hexafluoroisopropylidene)‐diphthalic anhydride (HDA) (99%), and propylene glycol monomethyl ether acetate (PGMEA) (≥99.5%) were obtained from Sigma‐Aldrich.…”

Organic Semiconductor/Polymer Blend Films for Organic Field‐Effect Transistors

“…The use of two solvents has also been applied for ink the jet printing of blends of a polythiophene derivative with PS, observing that morphologies with more crystalline domains were reached when using a high boiling point co-solvent. [68] The thin films morphologies are strongly dependant on the processing conditions. A recent study reports the evolution of TIPS-PEN crystallites when varying the spin-coating time (Figure 4).…”

Impact of p-type doping on charge transport in blade-coated small-molecule:polymer blend transistors

“…27 In recent years, molecular doping of OSCs has emerged as promising method to enhance the performance of solutionprocessed OTFTs. 18,[35][36][37][38][39][40][41][42][43][44][45][46][47][48] In this regard, we have recently developed p-doped OTFTs with hole mobility of 13 cm 2 V À1 s À1 based on spin-coated blend semiconducting channels based on the small-molecule 2,7-dioctyl [1]benzothieno [3,2-b] [1]benzothiophene (C 8 -BTBT), and the polymer poly(indacenodithiophene-cobenzothiadiazole) (C 16 IDT-BT). 16 Key to our success has been the ink-formulation engineering (solvents, material ratios, etc.…”