Toward Long Term Organic Solar Cell Device Stability via Thermocleavable Donor and Acceptor Active Layer

The performance of organic solar cell (OSC) was surged during past decades, however, the insufficient efforts to improve stability set the barriers to realize the practical applications for OSC devices. The morphological stability of OSC bulk heterojunction layer (BHJ) is apparently affected by the molecular mobilities of donors/acceptors under operational conditions. The introduction of thermocleavable side chains provides an effective and efficient method to reduce the dynamics of conjugated polymers (CP) to improve the thermal stability as evidenced by the enhanced <i>T</i>_g after fully cleavage. Furthermore, the newly synthesized donor-acceptor conjugated polymers (DA CPs) with thermocleavable contents were expected to achieve both good performance and stability for long term usage. This work focused on the investigations of the morphological changes as well as phase separation behaviors for thermocleavable donor/acceptor BHJ blend film. The solar cell devices were also prepared to evaluate the performance under various conditions. Finally, our work revealed the good performance and stable morphology over long term at elevated temperatures after alkyl side chains were completely removed, which could provide a pathway to improve the stability of optoelectronic properties in future OSC devices.