Low bandgap copolymers based on monofluorinated isoindigo towards efficient polymer solar cells

Abstract

To explore the effectiveness of monofluorinated isoindigo as an electron-deficient building block in push-pull conjugated polymers for organic solar cell applications, four low bandgap copolymers are effectively synthesized and characterized. The effects of fluorine introduction, thiophene spacer length and polymer molar mass on the general electro-optical polymer characteristics, thin film blend microstructure and electronic performance are investigated. Isoindigo monofluorination effectively improves the power conversion efficiency from 2.8 up to 5.0% upon molar mass optimization, without using any processing additives or post-treatments.

Recent structural evolution of lactam- and imide-functionalized polymers applied in organic field-effect transistors and organic solar cells

“…The asymmetrical uorine substitution was carried out in P87, in which one of the indolinone units had uorine substitution on its 7th carbon atom. 99 The P87:PCBM lm gave a PCE value of 5.03%, slightly higher than those of the above-mentioned TBIID-based polymers (Table 1). This is because the uorine-related inter-and intra-chain interactions could not only facilitate better backbone planarity but also form a well-mixed lm with PCBM.…”

Thieno[3,2‐b]thiophene‐Bridged Conjugated Polymers Based on Dithieno[3,2‐b:2′,3′‐d]silole and Thieno[3,4‐c]pyrrole‐4,6‐dione for Polymer Solar Cells: Influence of Side Chains on Optoelectronic Properties

“…The band gaps of P5 and P6 estimated from CV are 1.62 and 1.66 eV, respectively. The results indicate that the hexyl chain on the π bridge can successfully lower the HOMO and LUMO values of conjugated polymers, which is helpful for a higher open‐circuit voltage ( V oc ) …”

Synthesis of N,N′-dialkyl-6,6′-dibromoisoindigo Derivatives by Continuous Flow

“…The isoindigo core contains two fused lactam rings, inducing a strong electron-deficient character and, therefore, rendering it attractive as an acceptor component in push-pull type organic semiconductors. Nowadays, isoindigo has become a widely applied building block, with over 100 publications on its characteristics and use in polymer and molecular solar cells [35][36][37][38][39][40][41]. Power conversion efficiencies (PCE's) of 3.7 and 7.3%, respectively, have been reached for small molecule and polymer solar cells based on photoactive isoindigo-containing light-harvesting materials [40,41].…”