Efficient all-polymer solar cells based on thiazole-bridged middle band-gap polymer donor: The influence of alkyl side chain on polymer-polymer miscibility and photovoltaic performance

摘要

In this work, three middle band-gap (E-g approximate to 1.70 eV) polymer donors featuring thiazole moiety as pi bridge while different alkyl side chain modification were synthesized for all-polymer solar cell (APSC) application. The influence of the configuration of alkyl side chain (linear, branched and alkylthio) on polymer-polymer miscibility and resulting photovoltaic performance was systemically investigated. The results indicated that the miscibility of polymer-polymer pair was sensitive to the solubility of resultant polymers, which was caused by diverse alkyl side chain modification. Since then, the most soluble one (P1, modified by 2-ethylhexyl side chain) could produce efficient as-cast APSC device with best PCE of 6.42%, accompanying with high V-oc of 0.88 V and J(sc) of 14.22 mA cm(-2). This work revealed that while the incorporation of thiazole pi bridge into quinoid-based polymer proves to be an efficient molecule design strategy, suitable alkyl side chain modification is also important to enhance polymer-polymer miscibility.