Side chain structure and dispersity impact the photostability of low band gap polymers

Aurélien Tournebize (1, 2) , Isabel Fraga Dominguez (2) , Graham E. Morse (3) , Christine Taviot-Gueho (2) , Agnès Rivaton (2) , Heiko Peisert (1) , Thomas Chassé (1)

1 Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen
2 ICCF - Institut de Chimie de Clermont-Ferrand
3 Merck & Co. Inc - Merck Sharp and Dohme

A series of eight low band gap polymers based on benzodithiophene - diketopyrrolopyrrole (BDT-DPP) skeleton were designed with side chain variation on the benzodithiophene unit. The effect of different side chains, including -H, alkyl, alkoxy, and aryl moieties, over polymer stability is examined. Thin films were processed and submitted to photooxidative degradation. We experimentally confirm that alkoxy side chains are the most promising candidates for designing soluble and photo-resistant polymers. This conclusion is modulated by the polymer dispersity which also plays an important role: a low dispersity value being synonymous of higher photostability. The reasons why the side chain structure and dispersity value drive the polymer photostability are discussed. For the design of photo-resistant polymers and devices, side chain selection must go hand in hand with the control of the synthesis meaning a low dispersity.

Mots clés: Low band gap polymers; Photodegradation; Side chain structure; Dispersity

Domaines: Chimie

Aurélien Tournebize, Isabel Fraga Dominguez, Graham E. Morse, Christine Taviot-Gueho, Agnès Rivaton, et al.. Side chain structure and dispersity impact the photostability of low band gap polymers. Polymer Degradation and Stability, 2017, 146, pp.155 - 160. ⟨10.1016/j.polymdegradstab.2017.10.010⟩. ⟨hal-01685460⟩