A Large Area Organic Solar Module with Non-Halogen Solvent Treatment, High Efficiency, and Decent Stability

It is a challenge to fabricate organic solar modules with the combination of high efficiency, good stability, and green solvent treatment. To address the issue, active layer materials still play crucial roles. Herein, a non-fullerene acceptor CH7 with the extended conjugation central unit and long-branched side chains is reported for the fabrication of high-performance large-area modules. The long-branched alkyl chains can ensure CH7 to have good solubility in non-halogen solvent o-xylene (OX). Meanwhile, the steric hindrance of long-branched alkyl chains can suppress molecular excessive aggregation. The inverted structure prototype device based on PM6:CH7 and processed with OX showed a promising power conversion efficiency (PCE) of 17.49% mainly due to the favorable active layer morphology. Based on the small area device results, processed from OX, a 25.2 cm(2) module is fabricated and demonstrates a high PCE of 14.42% and good photo stability with maintaining 93% of its initial efficiency after 500 h continuous illumination. Moreover, the module also shows decent thermal stability, maintaining with 82% of its original efficiency after the thermal stress at 65 degrees C for 500 h.

Automated summary

A non-fullerene acceptor CH7 with extended conjugation and long-branched side chains is introduced for the fabrication of high-performance organic solar modules. The use of long-branched alkyl chains ensures good solubility of CH7 in non-halogen solvent OX and suppresses molecular aggregation. A prototype device utilizing PM6:CH7 and processed with OX exhibits a promising power conversion efficiency (PCE) of 17.49% due to favorable active layer morphology. A 25.2 cm(2) module fabricated from OX shows a high PCE of 14.42% and good photo stability, maintaining 93% of its initial efficiency after 500 h of continuous illumination.