Thienyl Sidechain Substitution and Backbone Fluorination of Benzodithiophene-based Donor Polymers Concertedly Minimize Carrier Losses in ITIC-based Organic Solar Cells
Type
ArticleAuthors
Khan, Jafar IqbalFirdaus, Yuliar

Cruciani, Federico

Liu, Shengjian
Anthopoulos, Thomas D.

Beaujuge, Pierre
Laquai, Frédéric

KAUST Department
Biological and Environmental Sciences and Engineering (BESE) DivisionChemical Science Program
KAUST Solar Center (KSC)
Material Science and Engineering Program
Physical Science and Engineering (PSE) Division
KAUST Grant Number
OSR-2018-CARF/CCF-3079Date
2020-04-22Online Publication Date
2020-04-22Print Publication Date
2020-05-14Embargo End Date
2021-04-22Permanent link to this record
http://hdl.handle.net/10754/662653
Metadata
Show full item recordAbstract
Non-fullerene acceptor (NFA) based organic solar cells have outperformed fullerene-based devices, yet their photophysics is less well understood. Herein, changes in the donor polymer backbone side-chain substitution and backbone fluorination in benzodithiophene (BDT)-thiophene copolymers are linked to the photophysical processes and performance of bulk heterojunction (BHJ) solar cells, using ITIC as NFA. Increased geminate recombination is observed when the donor polymer is alkoxy-substituted in conjunction with faster non-geminate recombination of free charges, limiting both the short circuit current and device fill factor. In contrast, thienylsubstitution reduces geminate recombination, albeit non-geminate recombination remains significant, leading to improved short circuit current density, yet not fill factor. Only the combination of thienyl-substitution and polymer backbone fluorination yields both efficient charge separation and significantly reduced non-geminate recombination, resulting in fill factors (FFs) in excess of 60 %. Time-delayed collection field measurements ascertain that charge generation is field-independent in the thienyl-substituted donor polymer:ITIC systems, while weakly field dependent in the alkoxy-substitued polymer:ITIC blend, indicating the low FFs are primarily caused by non-geminate recombination. This work provides insight into the interplay of donor polymer structure, BHJ photophysics, and device performance for a prototypical NFA, namely ITIC. More specifically, it links the donor polymer chemical structure to quantifiable changes of kinetic parameters and the yield of individual processes in ITIC-based BHJ blends.Citation
Khan, J. I., Firdaus, Y., Cruciani, F., Liu, S., Anthopoulos, T. D., Beaujuge, P. M., & Laquai, F. (2020). Thienyl Sidechain Substitution and Backbone Fluorination of Benzodithiophene-based Donor Polymers Concertedly Minimize Carrier Losses in ITIC-based Organic Solar Cells. The Journal of Physical Chemistry C. doi:10.1021/acs.jpcc.0c03282Sponsors
This publication is based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No: OSR-2018-CARF/CCF-3079.Publisher
American Chemical Society (ACS)Additional Links
https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.0c03282ae974a485f413a2113503eed53cd6c53
10.1021/acs.jpcc.0c03282