High performance electrochromic supercapacitors powered by perovskite-solar-cell for real-time light energy flow control

Electrochromic devices (ECDs) can alter their optical transmittances under external electrical power but are unable to spontaneously modulate the light flow in real-time along with the intensity change of surrounding light. To address this problem, a module of smart perovskite solar cell (PSC)-powered all-in-one gel ECDs was reported. The PSC-powered ECDs could modulate their transmittance swiftly in visible-infrared regions, hence regulating the photo energy flow in real time according to the surrounding light intensity. The ECD based on 4, 4′-(thiophene- 2, 5-diyl)bis(1-ethylpyridin-1-ium) diiodide (TEV) showed large optical contrast (79.7% at 570 nm, 64.9% at 908 nm), excellent coloration efficiency (231.2 cm/C), and outstanding stability (only 1.1% ΔT change after 60,000 cycles). The PSC-powered ECDs showed fast response time (≤5 s) and high stability (negligible degradation after 5000 s consecutive switching between bright and dark conditions in air). Meanwhile, the stored power accompanied with the electrochromic process could drive a red LED with high cyclic stability (95.6% of areal capacitance maintained after 10,000 charging-discharging cycles), indicating that ECDs can serve as ideal electrochromic supercapacitors (ECSs). In addition, the fabricated ECD with large area (5.0 cm × 5.4 cm) showed excellent thermal regulation (7 °C of temperature difference between colored and bleached states). We expect this work would pave a new way to save energy and improve energy efficiency in modern buildings and automobiles.