Energy saving electrochromic windows were achieved by controlling the interfacial charge transfer using low-HOMO level (EHOMO < −5 eV) π-conjugated polymers (CPs) as bistable electrochromic films and an ionic liquid as the electrolyte layer. It provided a long bistability (>90 min) at the voltage-off state with a high coloration efficiency (879 cm2 C−1).

A highly transparent electrochromic capacitive (ECC) window was explored by combining a high contrast electrochromic polymer (ECP) and a transparent capacitive polymer.

Highly transparent TiO 2 nanoparticles are explored as a non-electrochromic (non-EC) charge-balancing layer for a high color contrast, bistable electrochromic window (ECW). The TiO 2 nanoparticle (TNP) layer increases the potential at the EC polymer electrode, thereby lowering the working voltage of the ECW. This leads to lower the power consumption of ECWs without loss in the high color contrast (ΔT > 72%) and to remarkably improve the cyclability (ΔT change <1% over 3000 cycles), mainly due to the low overvoltage (<0.1 V) on the electrochromic polymer layer. Furthermore, the ECWs including the non-EC TNP layer show long-term bistability (>2.7 h, 40% increase) and UV stability (ΔT change <1%) to provide a low-power automatic ECW. This finding shows that the charge balanced ECP window has the potential to be used for an energy saving ECW with low-power consumption and will be widely applied in various ECWs as well as electrochemical devices with multiple functions.

A flexible conductive polymer film is demonstrated via solution casting method with high photothermoelectric effect. Crystallinity and conductivity of the film were controlled with the polymerization solution. The thin-film solar TE harvester shows the first and highest absorber-free organic solar TE output.