Enhancing the Thermal Stability of Organic Solar Cells by Locking Morphology with Ethyl Cellulose Additive

The morphology of active layer of the organic solar cells (OSCs) tends to transition toward its lowest energy conformation under thermal stress, significantly limiting the stability of OSCs. In this study, ethyl cellulose (EC) is utilized as an additive in the active layer of the typical PM6:Y6 and other systems. Due to the strong interaction between the hydroxyl groups of EC and the heteroatoms in the organic semiconductors, their bulk heterojunction nanomorphology is locked, thereby enhancing device thermal stability. Under thermal stress at 65 °C for 1,000 h, the PM6:Y6 device incorporating EC demonstrates excellent stability nearly without performance loss. Furthermore, compared to the control device, the device exhibits improved thermal stability under a range of more stringent aging conditions. Additionally, the EC additive shows broad applicability in various active layer systems, effectively enhancing their thermal stability. This work offers a promising approach for developing stable nanomorphology structures in OSCs.