Facile Growth Of Large Area Organic 1D Microwire Arrays And 2D Single-crystal Films, And Their Application In Photoelectric Device

Small molecule organic semiconducting micro/nanocrystals with tunable molecular design and property modulation have attracted considerable attention. Compared to inorganic materials, they are cost-effective, flexible, amenability to roll-to-roll large area producing, low-temperature processing requirements and inherent compatibility with plastic substrates. Getting perfect organic single-crystal nanostructures is the key to construct high-performance electronic and photonic devices, such as organic field-effect transistors(OFETs), highly sensitive sensors, photodetectors. But the 1D or 2D organic single-crystal nanostructures obtained through conventional method always distributed in a macroscopically random fashion on the substrate, which made the electrical, photoelectric performance research stay in a single device stage and limited the integrated application. So, large area organic single-crystal nanostructures can promote the large-scale integrated application of micro/nano crystal structure greatlyIn this thesis, we focused on facile growth of large area organic 1D microwire arrays and 2D single-crystal films, and their application in photoelectric device.Firstly, we report an unusual yet universal approach to rapidly growing organized C60 MWs films in situ that display highly periodic, tunable microscale wire arrays in square centimeter areas. Our approach is based on a facile photoresist channel template and an optimized dip-coating process. We further undertook experiments to find the relationship between concentration and lifting rate is linear, high concentration need fast lifting rate to cooperate during the dip-coating process. High-quality C60 MW arrays were obtained on a flexible substrate(PET) as well as on a rigid substrate(SiO2/Si) by this approach. C60 MW arrays can precisely deposited only on the regions with pretreated Au electrode pairs and we can control the number of the C60 MW at the same time. Photoresponse of the devices were further investigated under 532 nm green light illumination, the switching ratio was as high as 1000. And it can be configured as integrated photodetectors, avoiding direct photolithography on the organic nanostructures. Our method is useful, versatile, and potentially offers a foundation for use in the construction of large-scale high-performance functional intergrated organic crystal device.Secondly, we report a new way to grow large area 2D C10-BTBT single-crystal films on the millimeter scale. The new approach was called r-LB(reverse-Langmuir–Blodgett) assisted evaporation method. The solution of small organic molecules will lay flat on the surface of the water with the extension force. With the evaporation of solvent, organic molecules will assembled into a single-crystal thin film at the triple-phase contact line(solvent/water/air). The single-crystal thin film can be transferred to objective substrate arbitrarily, such as rigid substrate(SiO2/Si) and flexible substrate(PET). The average thickness of the single-crystal film is about 20-30 nm, and we can control the thickness from several to dozens of nanometer by changing solvent evaporation rate. Using the ultrathin single-crystal film as a semiconducting layer, high performance organic field-effect transistors(OFETs) are demonstrated with a mobility up to 10 cm2V-1s-1 and On/Off ratio up to 107. This large area 2D ultrathin single-crystal film indicating the bright future of the 2D crystals for future potential applications in organic integrated electronics together with the facile preparation process.