Anchored epitaxial growth of single-oriented one-dimensional organic nanowires towards their integration into field-effect transistors and polarization-sensitive photodetector arrays†

Abstract

The deliberate assembly of organic small molecules into single-oriented one-dimensional (1D) nanowires is essential for the large-scale, on-chip integration of organic nanowire-based (opto)electronic devices. However, achieving single-oriented 1D organic nanowires remains a considerable challenge, predominantly attributed to the intricate nucleation and growth behaviors of the molecules. Herein, an anchored epitaxial growth method was developed to facilitate the single-oriented growth of 1D organic nanowires using the parallel nanogrooves on the annealed sapphire as anchoring seed crystal templates. The depth of the nanogrooves was greater than the length of the molecules, enabling the molecules to be embedded into the V-shaped nanogrooves and to form anchored nuclei during the physical vapor deposition process. Subsequently, these nuclei exhibited directional epitaxial growth along the nanogrooves, resulting in the formation of single-oriented 1D organic nanowires. Various organic small molecule 1D nanowires with uniform molecular packing and orientation were obtained and utilized for subsequent device integration. 2,7-Dioctyl[1]benzothiophene (C8-BTBT) was used as a model material, and the flexible organic field-effect transistor (OFET) based on the single C8-BTBT nanowire exhibited a mobility of up to 1.5 cm² V⁻¹ s⁻¹. Benefiting from high mobility and uniform orientation, the integrated polarization-sensitive photodetector arrays based on 1D C8-BTBT nanowires exhibited a high dichroic ratio of up to 2.83, which was higher than those of some previously investigated 1D nanowires and two-dimensional materials. This work presents new opportunities to fabricate single-oriented 1D organic nanowires for integrated devices.