High mobility transistors based on electrospray-printed small-molecule/polymer semiconducting blends

Abstract

Spray-coating techniques have recently emerged as especially effective approaches for the deposition of small semiconducting molecules toward the fabrication of organic field-effect transistors (OFETs). Despite the promising mobility values and the industrial implementation capability of such techniques, the resulted devices still face challenges in terms of morphology control and performance variation. In this work, the efficient process control of electrostatic spraying deposition (ESD) and the excellent film properties of polymer:small molecule blends were successfully combined to develop reliable and high performance transistors. Specifically, a highly efficient blended system of 2,8-difluoro-5,11-bis(triethylsilylethynyl)-anthradithiophene (diF-TES-ADT) and poly(triarylamine) (PTAA) was employed in order to realize top-gate OFETs under ambient conditions, both on rigid and on flexible substrates. The films revealed an extensive crystallization and microstructural organization implying a distinct phase separation in the electrosprayed blend. Furthermore, we investigated the effects of the processing temperature on the film-forming properties by means of film continuity and grains boundaries.Remarkably, the electrosprayed OFETs exhibited field-effect mobilities as high as 1.71 cm 2 /Vs, and enhanced performance consistency when compared to conventional gas-sprayed transistors. Additionally, the transistors showed excellent electrical and environmental stability, indicative of the good interface quality and the selfencapsulation capability of top-gate structure. These results highlight the great potential of electrohydrodynamic atomization techniques for implementation to large-area processing for OFETs fabrication.

Printable and Flexible Phototransistors Based on Blend of Organic Semiconductor and Biopolymer

“…The active semiconducting layer of the blended‐OPT contains only 9 wt% of OSC, while the major component of the film is the PLA. It has been reported that blending polymer into the OSCs can significantly reduce the material cost and enhance the processability by cost‐efficient solution methods during OFET fabrication . Here, we demonstrated that blending the PLA into the OSC could lead to OFETs with decent transistor characteristics and enhanced photosensitivity.…”

“…Blending OSCs with polymers in the conducting channels can provide the device with a large area of interaction interface, and thus is expected to enhance the photosensitivities of aforesaid novel OPTs. Meanwhile, fabrication of OPTs combining OSC and polymer blends effectively reduces the material cost, provides the devices with better flexibility, and importantly, tunes the OSCs properties to make the semiconducting materials printable . In this work, OPTs based on blended structure (blended‐OPTs) and layered structure (layered‐OPTs) were both fabricated by using a common soluble OSC 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) and an insulating biopolymer polylactide (PLA), and the photoresponse performances of both OPTs under UV light were investigated and compared.…”

Recent Progress in High‐Mobility Organic Transistors: A Reality Check

“…Indeed, the impact of fabrication techniques on the versatile blend system has been demonstrated a number of times over the years. Examples of fabrication techniques include spray deposition, line printing, air brushing, inkjet printing, dipping processes, vertical flow, blade coating, and off‐center spin coating …”

The Impact of Molecular p‐Doping on Charge Transport in High‐Mobility Small‐Molecule/Polymer Blend Organic Transistors

“…This is expected from such measurements due to a reduction in the trapping rate as the trap states become occupied. To quantify the bias-stress effect in the two blend systems, we fitted a stretched exponential function to the experimental data using: [1] [20] [72]…”