We studied the charge-generation mechanism in low-bandgap polymer (P4TNTz-2F)-fullerene bulk heterojunction (BHJ) organic solar cells (OSCs) using transient absorption (TA) spectroscopy. The highly crystalline nanowire structure of P4TNTz-2F in a blend film prepared with chlorobenzene (CB) and 1,8-diiodooctane (DIO) induced more long-lived charge carriers than those in a blend film prepared with CB only. Pump-wavelength-dependent TA data revealed that the increased charge-delocalization by the intrachain ordering of P4TNTz-2F in the blend film prepared with CB/DIO is the key factor to increasing the OSC efficiency. The intrachain charge-delocalization increased the charge-transfer (CT) state lifetime and suppressed geminate recombination losses, resulting in the efficient dissociation of CT states into free carriers. Our findings provide new insights into the excited-state dynamics study of BHJ blends, which can serve as a good guide for the development of novel OSC materials.
|Number of pages||9|
|Journal||Journal of Physical Chemistry C|
|Publication status||Published - 2022 Feb 17|
Bibliographical noteFunding Information:
This work was supported by a grant (Code No. 2011-0031628) from the Center for Advanced Soft Electronics under the Global Frontier Research Program of the Korean government Ministry of Science and ICT (MSIT). This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2020R1I1A1A01054660) and the Faculty Research Fund of Sejong University in 2021. This work was also supported by the NRF grants funded by the MSIT (NRF-2019R1A2B5B02070657/NRF-2019M3D1A1078299/NRF-2019R1A2C1086262).
© 2022 American Chemical Society
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films