Dual-Layered Percolative Networks of Photoactive Materials and Elastomers for Highly-Stretchable, Efficient Organic Photovoltaics with Strain-Induced Power Enhancement up to 60% Strain

Abstract

Intrinsically stretchable organic solar cells (IS-OSCs) are emerging as wearable power sources due to their multi-directional stretchability. However, insufficient power conversion efficiency (PCE) and limited mechanical robustness hinder their practical applications. In this study, we develop efficient OSCs with extreme stretchability (crack-onset strain (COS) = 125%) by constructing dual-layered percolative (DLP) photoactive systems. These systems consist of 1) polymer donor (PD):elastomer (D18:SEBS) blends in the bottom layer and 2) PD:small-molecule acceptor (SMA) (PM6:L8-BO) blends in the top layer. The new DLP architecture enables independent control over the morphology in both layers, promoting well-interconnected networks that enhance both mechanical and photovoltaic properties. In the bottom layer (D18:SEBS), the co-continuous morphology of PDs and elastomers establishes robust mechanical scaffold while maintaining efficient charge transport. The top layer (PM6:L8-BO) forms a well-interconnected PD-SMA networks, which significantly enhances donor-acceptor interactions and charge carrier mobility. Our findings demonstrate that the percolative structures in both layers is crucial for improving both PCE and mechanical stretchability, highlighting their potential in practical IS-OSC systems. Specifically, OSCs based on D18:SEBS/PM6:L8-BO DLP system achieve an excellent PCE (15.7%) and stretchability (COS = 125%), outperforming brittle D18/L8-BO- (COS = 6%) and inefficient D18:SEBS/L8-BO devices (PCE = 11.5%). Importantly, D18:SEBS/PM6:L8-BO-based IS-OSCs exhibit a continuous increase in power output over a wide strain range (0−60%), representing the most mechanically-robust IS-OSCs reported to date.