Identifying tunneling effects of poly(aryl ether) matrices and boosting the efficiency, stability, and stretchability of organic solar cells

Tunneling effects are one of the most basic theories that have long been overlooked in the bulk-heterojunction (BHJ) layers of organic solar cells (OSCs). Herein, by fabricating BHJ and layer-by-layer (LbL) devices with five different poly(aryl ether)s (PAEs), we reveal a tunneling effect in the active layer of OSCs. The results show that the as-cast devices with 5 wt % and even 30 wt % PAE in PM6:Y6-blends achieve high power conversion efficiencies (PCEs) over 15%. Furthermore, the 5 wt % PAE-based devices with proper post-treatment deliver a PCE of 17.03%. By inserting a thin PAE layer with high dielectric constant, the LbL OSCs (PM6/PAE-237/Y6) yield a 23% improvement PCE compared to one without PAEs. With rational molecular design, we demonstrate that heat-resistant PAE matrices with high stretchability simultaneously improve efficiency, stability, and mechanical flexibility of OSCs. The proposed tunneling effect and PAE matrices strategy have important implications for fabricating efficient, stable, and flexible organic devices.