Low band-gap polymers incorporating benzotriazole and 5,6-dialkoxy-benzothiadiazole as solution processable electrochromic materials

Abstract

Abstract. Two series of donor-acceptor type conjugated polymers bearing benzotriazole or 5,6-dialkoxy-benzothiadiazole as acceptors unit are synthesized via Stille coupling. The optical, electrochemical, spectroelectrochemical characterizations and theoretical calculations are carried out. The polymers display excellent solubility in common organic solvents upon the introduction of long aliphatic side chains. The electrochromic performances of the polymers are also studied. Upon oxidation, the polymers switch from magenta or blue to a transmissive light blue state. In particular, respectable optical contrasts of about 44 and 40% are obtained in the visible and near infrared (NIR) region respectively for P2. The polymers also reveal fast switching of about from one second to a few seconds. In addition, P2 exhibits a high coloration efficiency of 518 and 561 cm 2 /C in the visible and NIR region respectively. The promising electrochromic behaviour of these polymers, together with the enhanced solubility will allow large-scale processing and advancement towards real applications.

Oligoaniline-containing electrochromic polymers with tunable properties

“…With the addition of current consumption, the coloration efficiency of these polymers are calculated to be 47 cm 2 /C (ECPA), 66 cm 2 /C (ECPA-TA), 53 cm 2 /C (ECPA-POSS), and 57 cm 2 /C (ECPA-F), respectively. Although the resulting coloration efficiency values are quite low compared to recent results from conjugated electrochromic polymers [4,24,25], the prepared polymer are still qualified as electrochromic material in the applications of light-adapting mirrors and smart windows. In addition, the switching speeds of the polymers are also determined from Figure 5b.…”

A Structurally Simple but High‐Performing Donor–Acceptor Polymer for Field‐Effect Transistor Applications

“…We note that previous reports on the use of dibrominated dFBTz as a co-monomer have reported similarly low molecular weights, [37] much lower than the analogous non-fluorinated BTz monomers. [48] It appears that the presence of the fluorine substituents impairs the cross-coupling polymerization. Figure 1 shows the absorption spectra of each of the polymers in both dilute chlorobenzene solution and as thin films.…”

The Photoelectric Properties of Polymer Acceptors Containing Oxadiazole and Thiadiazole

“…After the first publication of all‐PSCs in 1995, many π‐conjugated polymers containing electron‐deficient units, such as diketopyrrolopyrrole, cyano groups, and 2,1,3‐benzothiadiazole, especially, naphthalene diimide (NDI) and perylene diimide (PDI) have developed as potential electron‐acceptor materials for the application in all‐PSCs. Five‐membered heterocycles 1,3,4‐oxadiazole (OZ) and 1,3,4‐thiadiazole (TZ), containing two strongly electron‐withdrawing imine (CN) nitrogens, possess high electron affinity, good coplanarity, and heteroatom‐rich characteristics, which have been applied in light‐emitting devices and organic solar cells . However, to the best of our knowledge, it is less n‐channel OZ‐ and TZ‐based copolymers reported to date, which can be applied in solution‐processable all‐PSCs.…”

“…[7][8][9][10][11] Conversely, nonfullerene acceptors have many advantages, such as low cost, strong (2 of 6) 1700094 and 1,3,4-thiadiazole (TZ), containing two strongly electron-withdrawing imine (CN) nitrogens, possess high electron affinity, good coplanarity, and heteroatom-rich characteristics, which have been applied in light-emitting devices and organic solar cells. [20][21][22] However, to the best of our knowledge, it is less n-channel OZ-and TZ-based copolymers reported to date, which can be applied in solution-processable all-PSCs. Considering the unique properties of OZ and TZ, two novel donor-acceptor (D-A)conjugated polymers bearing OZ-or TZ-acceptor moieties, i.e., PNOZ and PNTZ (Figure 1), have been developed, where simple thiophene units were used as the weak electron donor units and alkylated-NDI as the second acceptor units.…”