Ryu Ka Yeon, Lee Juhwan, Jun Taesuk, Lee Daeyeon, Kim BongSoo, Ryu Du Yeol, Kim Kyungkon
Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea.
Research Institute for Green Energy Convergence Technology (RIGET), Gyeongsang National University, Jinju 52828, Republic of Korea.
ACS Appl Mater Interfaces. 2022 May 25;14(20):23474-23486. doi: 10.1021/acsami.2c03340. Epub 2022 May 15.
To commercialize organic solar cells (OSCs), changes in the optimized morphology of the photoactive layer caused by external stimuli that cause degradation must be addressed. This work improves OSC stability by utilizing the cross-linking additive 1,8-dibromooctane (DBO) and a sequential deposition process (XSqD) to fabricate the photoactive layer. The cross-linking additive in the donor polymer (PTB7-Th) improves polymer crystallinity and immobilizes the crystalline morphology by partial photo-cross-linking. Ellipsometry experiments confirm the increase in the glass transition temperature of cross-linked PTB7-Th. The polymer crystallinity is further improved after removal of non-cross-linked polymer and residual additive by chlorobenzene. The cross-linked polymer layer forms an efficient and stable heterojunction with a nonfullerene acceptor (IEICO-4F) layer via an XSqD process. The OSC based on the immobilized PTB7-Th exhibits excellent stability against light soaking and thermal aging.
