Recently, conjugated donor-acceptor block copolymers (CDABPs) were synthesized by one-pot polymerization and applied in polymer solar cells with a single-component active layer. These polymers can suppress phase separation and exhibit inert internal morphologies compared to the polymer blends; however, their thermal stability remains an issue to be addressed. In this study, we successfully synthesized a new crosslinkable CDABP (P(OXBTT-co-NDI2T)), comprising a donor block bearing photocrosslinkable oxetane side chains and an acceptor block to improve the thermal and morphological properties. The crosslinked P(OXBTT-co-NDI2T) film showed high solvent resistance, and it was confirmed that even the P(NDI2T) block without a crosslinking unit did not dissolve after washing with a solvent. This indicates that the P(NDI2T) block was obviously covalently bonded to the P(OXBTT) donor block in the CDABP structure. In particular, compared to the blend (P(OXBTT) and P(NDI2T)) film, the P(OXBTT-co-NDI2T) film exhibited a uniform surface morphology. Consequently, the polymer solar cell based on the crosslinked P(OXBTT-co-NDI2T) active layer showed higher power conversion efficiency and better thermal stability than that based on the blend film.
Bibliographical noteFunding Information:
The authors acknowledge the financial support from the National Research Foundation of Korea (NRF-2019R1A6A1A11044070, 2020R1I1A1A01066897, and 2022R1A2B5B02001454). We are grateful to the Institute for Basic Science (IBS, Korea) for allowing us to obtain nuclear magnetic resonance data (NMR; Ascend 500, Bruker). The Korea Basic Science Institute (Seoul) is acknowledged for the MALDI-TOF MS and TEM data.
© 2022 The Royal Society of Chemistry
ASJC Scopus subject areas
- Polymers and Plastics
- Organic Chemistry