3. CONCLUSION
In summary, we have successfully
designed and synthesized three
novel NFREAs OC4-4Cl-Ph , OC4-4Cl-Th andOC4-4Cl-C8 with hexylbenzene, hexylthiophene and octyl side
chains at the π-bridge units.
According to our results, the
LUMO energy levels decrease from OC4-4Cl-Ph toOC4-4Cl-Th and OC4-4Cl-C8 . Notably,
the OC4-4Cl-C8 exhibits
a longer exciton diffusion distance and the corresponding blend film
(D18:OC4-4Cl-C8 ) displays faster hole transfer and
diffusion-mediated processes, weaker bimolecular recombination, and more
efficient exciton transport.
Furthermore, the D18:OC4-4Cl-C8 blend films form favourable
nano fibril-like interpenetrating networks, which could facilitate
exciton dissociation and charge transport. Ultimately, theOC4-4Cl-C8 devices can achieve the highest PCE of 16.56% with
a low E loss of 0.56 eV, which is much higher thanOC4-4Cl-Ph (12.29%) to OC4-4Cl-Th (11.00%) based
ones. To the extent that we know, 16.56% is the highest PCEs of NFREA
based devices up to now. Our work
demonstrates that side-chain engineering is an efficient way to
fabricate high-performance NFREAs.
Acknowledgements
Financial support from the National Natural Science Foundation of China
(52173174, 51933001, 22109080), the Natural Science Foundation of
Shandong Province (no. ZR2022YQ45), the Taishan Scholars Program (no.
tstp20221121 and no. tsqnz20221134). A portion of this work is based on
the data (GISAXS) obtained at BSRF-1W1A. The authors gratefully
acknowledge the cooperation of the beamline scientists at BSRF-1W1A
beamline.
Xinming Zheng and Wenlong Liu contributed equally to this work.