Photoresponsive nanoscale columnar transistors

Abstract

This study reports a general methodology for making stable high-performance photosensitive field effect transistors (FET) from self-assembled columns of polycyclic aromatic hydrocarbons by using single-walled carbon nanotubes (SWNTs) as point contacts. In particular, the molecules used in this work are liquid crystalline materials of tetra(dodecyloxy)hexabenzocoronenes (HBCs) that are able to self-organize into columnar nanostructures with a diameter similar to that of SWNTs and then form nanoscale columnar transistors. To rule out potential artifacts, 2 different structural approaches were used to construct devices. One approach is to coat thin films of HBCs onto the devices with the SWNT-metal junctions protected by hydrogensilsesquioxane resin (HSQ), and the other is to place a droplet of HBC exactly on the nanogaps of SWNT electrodes. Both types of devices showed typical FET behaviors, indicating that SWNT-molecule-SWNT nanojunctions are responsible for the electrical characteristics of the devices. After thermally annealing the devices, HBC molecules assembled into columnar structures and formed more efficacious transistors with increased current modulation and higher gate efficiency. More interestingly, when the devices were exposed to visible light, photocurrents with an on/off ratio of >3 orders of magnitude were observed. This study demonstrates that stimuliresponsive nanoscale transistors have the potential applications in ultrasensitive devices for environmental sensing and solar energy harvesting.chemistry ͉ field effect transistor ͉ nanofabrication ͉ nanoscience ͉ self-assembly F abrication of molecule-scaled transport junctions that enable the measurement of the electrical characteristics of a small numbers of molecules could be of substantial importance to the improvement of molecular electronics. Recent years have witnessed the significant progress in molecular electronics, exemplified by a comprehensive set of proof-of-concept experiments (1-6). In this area, the big challenge is still the construction, measurement, and understanding of the current-voltage responses of the electronic circuits in which molecular systems play an important role as conducting elements. Because single-walled carbon nanotubes are quasi-1D ballistic conductors that have the molecule-scale width and length suitable for nanofabrication and the wealth of optoelectronic properties (7-17) they have demonstrated potential applications as fundamental building blocks in nanoelectronic and nanophotonic devices and offer substantial promise for integrated nanosystems. In particular, they could be, in principle, the ideal electrodes having significant advantages over metal electrodes for testing molecular conductance.Recently we and others (9,16,(18)(19)(20)(21)(22) have developed different methods for forming the nanogaps for electrical attachment of single molecules onto the ends of carbon nanotubes, thus permitting single-walled carbon nanotubes (SWNTs) as electrodes to enrich the measurements of single molecules. In our syste...

Photoresponsive Supramolecular Organometallic Nanosheets Induced by PtII⋅⋅⋅PtII and CH⋅⋅⋅π Interactions

“…We tested a total of five devices and found that the modulation of conductivity with light was reproducible. Although the performance of these photoresponsive transistors [17] has not been optimized, the photoresponsive properties of the nanosheets are promising for organometallic-based optoelectronics. No charge accumulation in the initial several seconds was observed.…”

Current Trends in Shrinking the Channel Length of Organic Transistors Down to the Nanoscale

“…We have demonstrated that SWCNTs can function as efficient point contacts for nanoscale FETs. We made FETs out of both monolayers [54] and self-assembled columns [80] of polycyclic aromatic hydrocarbons. These devices are ultrasensitive to their chemical environment, temperature, and light.…”

“…In order to make the photoresponsive transistors [80] we used the liquid crystalline material tetra(dodecyloxy)hexabenzocoronene (Fig. 12A).…”

The Role of Building‐Block Metrics in the Halogen‐Bonding‐Driven Self‐Assembly of Calixarenes, Inorganic Salts and Diiodoperfluoroalkanes

“…[10] In particular, bromo-and iodo-substituted PFCs are nicely tailored to halogen-bonding-based supramolecular chemistry and behave as robust tectons in crystal engineering. [11] The strength of halogen bonding depends both on the electron deficiency at the donor site and on the Abstract: Halogen bonding effectively co-operates with ion-ion interactions in determining the supramolecular structure of three-component heteromeric crystals comprising of calix [4]arenes, inorganic salts and diiodoperfluoroalkanes. The subtle interplay between these two types of interactions, as well as the influence of the valence of the metal ion, the "size" of the calixarene platform and the length of the perfluorocarbon module on the stoichiometry and overall supramolecular organisation of the ternary supramolecular architectures is discussed.…”

“…[1] Molecular building blocks are typically organised into higher-order functional structures through the use of noncovalent interactions. New properties arise as a result of this aggregation, [2] which are expressed in a supramolecular function that has found applications in fields ranging from biomimetic structures [3] to molecular electronics [4] and nanoscience. [5] Predicting and designing supramolecular architectures is difficult because of the weakness of the interactions involved.…”