Preparation of various morphological films at nanoscale by phase separation method

Abstract

A film consisting of nanopore and nanopillar structures was produced from a binary immiscible polymer solution of poly(amic acid) (PAA) and polyimide (PI), which can be used as a potential light extraction layer or flexible substrate in organic light-emitting diode (OLED) devices. A phase separation method was applied to create uniform and random pattern structures in nanoscale via a simple spin-coating technique. Firstly, the binary immiscible polymer solutions of PAA and PI whose precursor is carbazole-based dianiline were prepared with various volume ratios, and then the polymer mixtures were spin-coated onto substrates to form transparent films with various morphologies and dimensions, as observed by a field emission scanning electron microscope technique. In addition, after annealing PAA/PI films at 300 °C, the homogenous and flexible characteristic of nanopore and nanopillar structures could be achieved.