Optically switchable organic field-effect transistors based on photoresponsive gold nanoparticles blended with poly(3-hexylthiophene)

Abstract

Interface tailoring represents a route for integrating complex functions in systems and materials. Although it is ubiquitous in biological systems-e.g., in membranes-synthetic attempts have not yet reached the same level of sophistication. Here, we report on the fabrication of an organic field-effect transistor featuring dualgate response. Alongside the electric control through the gate electrode, we incorporated photoresponsive nanostructures in the polymeric semiconductor via blending, thereby providing optical switching ability to the device. In particular, we mixed poly(3-hexylthiophene) with gold nanoparticles (AuNP) coated with a chemisorbed azobenzene-based self-assembled monolayer, acting as traps for the charges in the device. The light-induced isomerization between the trans and cis states of the azobenzene molecules coating the AuNP induces a variation of the tunneling barrier, which controls the efficiency of the charge trapping/detrapping process within the semiconducting film. Our approach offers unique solutions to digital commuting between optical and electric signals.O rganic field-effect transistors (OFETs) are basic building blocks for logic applications and for the development of electronic technologies based on soft matter (1-4). Currently, the greatest challenges in the field are the achievement of higher device performance and the development of devices featuring uncommon and multiple functionalities (5). In this regard, hybrid organic-inorganic materials are gaining much attention because, besides their easy processing, they can take advantage of the tunability of the chemical properties of the components, and thus of the material as a whole. Nanoparticles (NPs) of different materials (gold, silver, metal oxides, etc.) can be coated with selfassembled monolayers (SAMs) of a given molecular system, thereby providing them additional functions such as a specific surface energy or optoelectronic properties (6-8). These features can be optimized by achieving control over the packing of SAMs on the NPs (7). When NPs are integrated in a device, they can, for example, act as charge storage sites-i.e., trapping charges centers, allowing the system to act as a memory (9, 10).The incorporation of photochromic molecules into electronic devices to confer them a photoresponsive nature has been recently explored (11)(12)(13)(14). Among photochromic systems (15-18), azobenzene derivatives are known to undergo isomerization from trans to cis form, and vice versa, under illumination at a specific wavelength, as well as from cis to trans with temperature (15). In the last few years, we have extensively investigated the thiol-substituted azo-biphenyl (AZO, Fig. 1A) when chemisorbed on gold surfaces (19)(20)(21)(22). We demonstrated that such a SAM chemisorbed on the planar source and drain electrodes of an OFET can be used to modulate optically the charge injection at the metal-semiconductor interface because of the different tunneling barrier of the cis and trans SAMs (19). However, the observed light-modul...

Organic Semiconductor/Gold Interface Interactions: From Physisorption on Planar Surfaces to Chemical Reactions with Metal Nanoparticles

“…surface plasmon resonance) and changes in the electronic properties of NPs are observed. [6,7] For this reason, metal NPs are nowadays often merged with (organic) semiconductors to form hybrid materials that can be employed in various devices, such as solar cells, [8][9][10] light-emitting diodes, [11,12] field-effect transistors [13,14] and non-volatile memories. [15,16] Because of the technological relevance of these hybrid materials and the above-mentioned possible catalytic properties of metal NPs, which are associated with enhanced chemical reactivity, it is important to investigate the nature of the interaction between NPs and a host matrix composed of an organic semiconductor.…”

Flexible non-volatile optical memory thin-film transistor device with over 256 distinct levels based on an organic bicomponent blend

“…Photochromic molecules have shown promising results as molecular switches, but rather mediocre (semi)conducting behaviour and nonnegligible fatigue [34][35][36] . Most studies on organic memories based on photochromic molecules have focused on three types of photochromic system: azobenzenes, spiropyrans and diarylethenes (DAEs) [37][38][39][40] . Optical switching between two independently addressable states leads to changes both at the molecular and the macroscopic scale.…”

Synergistic Photomodulation of Capacitive Coupling and Charge Separation Toward Functional Organic Field‐Effect Transistors with High Responsivity

“…In fact, integrating photochromics into organic electronic circuits has been proven to be reliable for constructing new generations of multifunctional interfaces such as an electrode/semiconductor interface, [ 13 ] environment/ semiconductor interface, [ 11,14 ] or even as a binary mixture in the active layer [ 15 ] to impart light-responsive properties into OFETs. Figure 1 shows a standard top-contact, bottom-gate OFET device architecture on the n ++ silicon substrates.…”