Poly(3,4-ethylenedi-oxythiophene) (PEDOT) derivatives conducting polymers are known for their great electrochromic (EC) properties offering a reversible blue switch under an applied voltage. Characterizations of symmetrical EC devices, built on combinations of PEDOT thin films, deposited with a bar coater from commercial inks, and separated by a lithium-based ionic membrane, show highest performance for 800 nm thickness. Tuning of the color is further achieved by mixing the PEDOT film with oxides. Taking, in particular, the example of optically inactive iron oxide Fe2O3, a dark blue to reddish switch, of which intensity depends on the oxide content, is reported. Careful evaluation of the chromaticity parameters L*, a*, and b*, with oxidizing/reducing potentials, evidences a possible monitoring of the bluish tint.

Accurate control of residual defect density is required for reliable investigation and use of ferroelectric materials. After reviewing the long term endeavor to decrease defect contributions in bulk materials, which reached mass production decades ago, recent challenges are underlined. These mostly result from the continuous trend towards integration which has reached the nanometre range. The contribution of solid state chemistry is of key relevance for improving the present processing routes and suggesting alternative ones, for example by controlling a large density of charged defects to reach unprecedented functionalities. Some of these breakthroughs are reviewed.