Sequential Blade-Coated Acceptor and Donor Enables Simultaneous Enhancement of Efficiency, Stability, and Mechanical Properties for Organic Solar Cells

As a predominant fabrication method of organic solar cells (OSCs), casting of a bulk heterojunction (BHJ) structure presents overwhelming advantages for achieving higher power conversion efficiency (PCE). However, long-term stability and mechanical strength are significantly crucial to realize large-area and flexible devices. Here, controlling blend film morphology is considered as an effective way toward co-optimizing device performance, stability, and mechanical properties. A PCE of 12.27% for a P-i-N-structured OSC processed by sequential blade casting (SBC) is reported. The device not only outperforms the as-cast BHJ devices (11.01%), but also shows impressive stability and mechanical properties. The authors corroborate such enhancements with improved vertical phase separation and purer phases toward more efficient transport and collection of charges. Moreover, adaptation of SBC strategy here will result in thermodynamically favorable nanostructures toward more stable film morphology, and thus improving the stability and mechanical properties of the devices. Such co-optimization of OSCs will pave ways toward realizing the highly efficient, large-area, flexible devices for future endeavors.