Solar Energy Materials and Solar Cells, Vol.195, 114-121, 2019
Novel triazine-centered viologen analogues for dual-band electrochromic devices
Dual-band electrochromic device (Db-ECD) can tune visible and near-infrared (NIR) radiation independently. The Db-ECDs have inspired considerable interest for their potential applications in smart windows and camouflage. Organic small molecules and polymers were examined carefully though, exploring organics with dual-band electrochromism is still challenging. Herein, the triazine-centered viologen analogues, 2,4,6-tri(pyridyl-4-propyl)-1,3,5-triazine bromide (TPPT) and 2,4,6-tri(pyridyl-4-benzyl)-1,3,5-triazine bromide (TPBT) show excellent dual-band electrochromic behaviors with high dynamic contrasts (66.63% at 887 nm and 50.71% at 600 nm for TPPT, and 59.79% at 900 nm and 66.90% at 600 nm for TPBT, respectively). The Db-ECDs fabricated via gel electrolyte mixed with TPPT or TPBT can work at a low driving voltage down to similar to 0.6 V, rendering a high coloration efficiency (up to 230.94 cm(2)C(-1)) in the NIR region, the absorbance difference at 1037 nm reaching up to 2.58 for TPPT. This work sets the stage for novel organic materials of dual-band electrochromic gadgets.
Keywords:Dual-band electrochromic devices;2,4,6-Tri(4-pyridyl)-1,3,5-triazine;NIR and visible radiation;Smart windows