Ageneral methodology towards stable high‐performance photocontrollable organic thin‐film transistors (OTFTs) by using photochromic spiropyrans (SP) combined with polymethyl methacrylate (PMMA) as a photoactive gate dielectric is reported. Capacitance and mobility transitions are demonstrated theoretically and experimentally when the SP molecules undergo their documented reversible photoisomerization. This universal strategy of incorporating molecular functionalities into OTFTs offers attractive new prospects for the development of molecular devices with tailored electronic and other properties.
Graphene behaves as a robust semimetal with the high electrical conductivity stemming from its high‐quality tight two‐dimensional crystallographic lattice. It is therefore a promising electrode material. Here, a general methodology for making stable photoresponsive field effect transistors, whose device geometries are comparable to traditional macroscopic semiconducting devices at the nanometer scale, using cut graphene sheets as 2D contacts is detailed. These contacts are produced through oxidative cutting of individual 2D planar graphene by electron beam lithography and oxygen plasma etching. Nanoscale organic transistors based on graphene contacts show high‐performance FET behavior with bulk‐like carrier mobility, high on/off current ratio, and high reproducibility. Due to the presence of photoactive molecules, the devices display reversible changes in current when they are exposed to visible light. The calculated responsivity of the devices is found to be as high as ∼8.3 A W−1. This study forms the basis for making new types of ultrasensitive molecular devices, thus initiating broad research interest in the field of nanoscale/molecular electronics.
A responsivity as high as five orders of magnitude is achieved for hybrid photodetectors fabricated by the surface functionalization of single‐walled carbon nanotubes with ZnO nanoparticles as antennas for UV detection. Due to the photoinduced adsorption and desorption of oxygen from the nanoparticle surface (see picture), the devices show photoswitching effects with good reversibility and reproducibility.
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