Direct fabrication of electrochromic devices with complex patterns on three-dimensional substrates using polymeric stencil films

Abstract

We present a direct fabrication technique for electrochromic devices with complex shapes including weakly supported and unsupported patterns on three-dimensional (3D) substrates. For this work, we employed freestanding polymeric stencil films as shadow masks, and performed two-step shadow masking processes. Using this technique, not only flexible materials but also rigid materials such as metals and other inorganic materials can be directly deposited onto non-flat substrates, realising complex shapes and high uniformity. Weakly supported and even unsupported patterns (i.e., island and ring shapes) of rigid materials were successfully achieved on both flat and non-flat substrates. Eventually, electrochromic display devices based on tungsten trioxide (WO3) with various shapes were also demonstrated on the 3D substrates as well. We anticipate that this fabrication technique will significantly contribute to the development of various integrated thin-film devices on complex-structured substrates, which may lead to further applications.