Synthesis and Characterization of Novel D-A Type Neutral Blue Electrochromic Polymers Containing Pyrrole[3-c]Pyrrole-1,4-Diketone as the Acceptor Units and the Aromatics Donor Units with Different Planar Structures

Abstract

Three soluble conjugated polymers, named BEDPP, FLDPP, and CADPP, were prepared through the Suzuki polymerized reaction, and employed benzene (BE), fluorene (FL), and carbazole (CA) as the donor units, respectively. The electron-deficient molecule 2,5-bis-(2-octyldodecyl)-3,6-bis-(5-bromo-thiophene)-pyrrole[3-c]pyrrole-1,4-diketone(DPP) was introduced and used as the acceptor unit. The properties of these three copolymers were studied by a series of detailed characterization analysis, including X-ray photoelectron spectroscopy (XPS), colorimetry, electrochemical measurements, spectroelectrochemistry, kinetics, quantitative calculation, and thermogravimetric (TG) analysis, etc. The results revealed that BEDPP displayed a blue color in the neutral state and a light brown color in the oxidized state, FLDPP exhibited a cyan color in the neutral state and a gray color in the oxidized state, while CADPP displayed pure blue color in the neutral state and a light gray color in the oxidized state. All these polymers possess narrow optical band gaps lower than 1.80 eV and satisfactory thermal stability. The kinetic characterization showed that the optical contrasts (ΔT%) in the near-infrared region were superior to the visible region. The optical contrasts of BEDPP, FLDPP, and CADPP are 41.32%, 42.39%, and 45.95% in the near-infrared region, respectively, which made them a good application prospect in the near-infrared region. Amid the three polymers, CADPP has the highest coloration efficiency (around about 288 cm2·C−1) and fast switching times (0.77 s in the coloring process and 0.52 s in the bleaching process) in the visible region, and the comprehensive performance of CADPP can be comparable to that of the reported D-A (Donor-Acceptor) type blue color polymers. In general, based on the good performances and the stable neutral blue color, the three polymers had profound theoretical significance for the development of electrochromic material and the completion of the RGB (Red, Green, Blue) color space.

Electrodeposited Gold Nanostructures for the Enhancement of Electrochromic Properties of PANI–PEDOT Film Deposited on Transparent Electrode

“…Optical change was monitored at the same wavelengths as were used in the previous experiment. Coloration efficiency (CE) was calculated according to the following Equations [46]:…”

Organic Thin Films Based on DPP-DTT:C60 Blends Deposited by MAPLE

“…Usually, DPP-DTT in film form discloses a small number of its infrared bands [41]. Accordingly, in the FTIR spectra of the P5, P6, and P7 samples featured by a higher thickness, 190, 160, and 200 nm, respectively, the specific vibrations of this conjugated polymer can be identified at about 786 cm −1 associated with the C-H bonds (out of plane bending vibration) from the thiophene rings, 1063 cm −1 related to the C-N bonds (stretching vibration) from the DPP group, 1360 cm −1 attributed to the C-H bonds (in plane bending vibration) from the methyl units, 1684 cm −1 related to the C=O bonds (skeleton vibration), 2855 cm −1 correlated to the saturated C-H bonds (symmetrical stretching), and 2931 cm −1 linked to the C-H bonds (asymmetrical stretching) on the thiophene ring [42]. If the characteristic vibrations of the conjugated polymer are clearly identified in the FTIR spectra of the DPP-DTT:C60 thin films deposited by MAPLE, the typical vibrations of C60 located at about 525, 574, and 1430 cm −1 [43] can be barely noticed in these spectra due to their weak intensity.…”

A Review on the Materials Science and Device Physics of Semitransparent Organic Photovoltaics

“…Another prominent design strategy that dominates synthetic efforts are donoracceptor (DA) type polymers, consisting of alternating electron-rich and electron-poor motives [31,32,[39][40][41][42][43]. The interaction of the donor's highest occupied molecular orbital (HOMO) with the acceptors' HOMO leads to the formation of two hybrid orbitals of non-degenerate energy, thus one level being energetically lower than the HOMOs of the isolated moieties, as described by MO theory [44,45].…”