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.