In this study, we newly synthesized iron phthalocyanine incorporated iron metallo-supramolecular polymers (Pc-Fe-polymer) and investigated its electrochromic behavior in both solution and solid-state devices. The presence of a terpyridine-attached iron phthalocyanine (FePc-TP) spacer revealed long-wavelength absorption at 670–700 nm, and the metal-to-ligand charge transfer (MLCT) by Fe-terpyridine coordination induced another absorption at 578 nm. Consequently, the Pc-Fe-polymer covered broad ranges of visible and near-infrared regions. Furthermore, due to facile charge delocalization during the Fe2+ to Fe3+ redox process, the Pc-Fe-polymer exhibited enhanced electrochromic performances. The Pc-Fe-polymer film experienced reversible electrochromic switching by changing the color from dark blue to transparent green in both solution and solid-state devices using LiClO4 as an electrolyte. The Pc-Fe-polymer exhibited exceptionally high switching stability (>1000 times) and a high coloration efficiency of 346.7 cm2/C and 211.4 cm2/C in solution and solid-state devices, respectively. Besides, we successfully demonstrated the feasibility of applying the Pc-Fe-polymer for flexible electrochromic devices on a plastic substrate. This study’s results suggest a designing concept for electrochromic materials that have highly stable and efficient switching for smart display and window applications.

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Organic-molecule fluorophores with emission wavelengths in the second near-infrared window (NIR-II, 1000–1700 nm) have attracted substantial attention in the life sciences and in biomedical applications because of their excellent resolution and sensitivity. However, adequate theoretical levels to provide efficient and accurate estimations of the optical and electronic properties of organic NIR-II fluorophores are lacking. The standard approach for these calculations has been time-dependent density functional theory (TDDFT). However, the size and large excitonic energies of these compounds pose challenges with respect to computational cost and time. In this study, we used the GW approximation combined with the Bethe-Salpeter equation (GW-BSE) implemented in many-body perturbation theory approaches based on density functional theory. This method was used to perform calculations of the excited states of two NIR molecular fluorophores (BTC980 and BTC1070), going beyond TDDFT. In this study, the optical absorption spectra and frontier molecular orbitals of these compounds were compared using TDDFT and GW-BSE calculations. The GW-BSE estimates showed excellent agreement with previously reported experimental results.

Recently, fullerene derivatives have received significant attention due to their potential impacts on the development of high performance organic photovoltaic (OPV) cells. One of the most successful fullerene derivatives thus far is [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM), which is being used as an electron acceptor material. However, PCBM has some disadvantages concerning its application in OPV cells, such as a weak absorption rate in the visible region and a relatively low LUMO level. In the present work, we synthesized a novel fullerene derivative, called hexyl perylene fullerene (HPF), which contains a hexyl perylene moiety. The HPF molecules showed two absorption peaks at 340 nm and 450 nm corresponding to the fullerene and to the perylene moiety, respectively. 1,8-octanedithiol was used as an additive to improve the compatibility between the poly(3-hexylthiophene) (P3HT) and the synthesized HPF The characteristics of an OPV cell composed of ITO/PEDOT:PSS/P3HT:HPF:1,8-octanedithiol/Al were investigated.