Benzodithiophene and Imide-Based Copolymers for Photovoltaic Applications

Abstract

Conjugated alternating copolymers were designed with low optical band gaps for organic photovoltaic (OPV) applications by considering quinoid resonance stabilization. Copolymers of thienoisoindoledione (TID) and benzodithiophene (BDT) had appreciably lower band gaps (by ∼0.4 eV) than copolymers of thienopyrroledione (TPD) and BDT. In addition to intramolecular charge transfer stabilization (i.e., the “push-pull” effect), the former copolymer’s quinoid resonance structure is stabilized by a gain in aromatic resonance energy in the isoindole unit. Additionally, the HOMO levels of the copolymers could be tuned with chemical modifications to the BDT monomer, resulting in open circuit voltages of greater than 1 V in photovoltaic devices. Despite the optimized band gap, TID containing polymers displayed lower photoconductance, as determined by time-resolved microwave conductivity, and decreased device efficiency (2.1% vs 4.8%) as compared with TPD analogues. These results were partially attributed to morphology, as computational modeling suggests TID copolymers have a twisted backbone, and X-ray diffraction data indicate the polymer films do not form ordered domains, whereas TPD copolymers are considerably more planar and are shown to form partially ordered domains.

Capturing Mobile Lithium Ions in a Molecular Hole Transporter Enhances the Thermal Stability of Perovskite Solar Cells

“…A huge number of acceptor units have been employed to synthetize conjugated semiconducting materials, especially for bulk heterojunction organic solar cells. For example, 1,4-diketopyrrolopyrrole, [27][28][29] 2,1,3-benzothiadiazole, [30][31][32][33] isoindigo, [34][35][36] thienoisoindoledione, [37,38] and bithiopheneimide and their derivatives [39][40][41] are widely used because of their strong electron-withdrawing characteristics. In particular, imide-functionalized aromatic groups such as thienoisoindoledione, thieno[3,4-c]pyrrole-4,6-dione, [42][43][44][45][46] and bithiopheneimide are attractive acceptor units to be used as a central acceptor unit in D-A molecules.…”

Anthracene‐thieno[3,4‐c]pyrrole‐4,6‐dione based donor–acceptor conjugated copolymers for applications in optoelectronic devices

“…Copolymers comprising alternating benzo[1,2‐ b :4,5‐ b ']dithiophene units and electron‐donating units have been reported in literature . However, to the best of our knowledge, nobody has reported any alternating TPD‐anthracene copolymers.…”

Radical-mediated dehydrative preparation of cyclic imides using (NH4)2S2O8–DMSO: application to the synthesis of vernakalant

“…Cyclic imides have found immense applications in agrochemicals such as chlorophthalim (herbicide), captan (fungicide), flumipropyn (herbicide), flumioxazin (herbicide), procymidone (pesticide) and cinidon-ethyl (herbicide) [ 18 – 19 ]. Imides are the backbones of several commercially available high-performance polymers [ 20 – 21 ] and many other advanced materials [ 22 – 25 ].…”