Ultrafast Transient Spectroscopy of Polymer/Fullerene Blends for Organic Photovoltaic Applications
- Univ. of Utah, Salt Lake City, UT (United States). Dept. of Physics and Astronomy
We measured the picoseconds (ps) transient dynamics of photoexcitations in blends of regio-regular poly(3-hexyl-thiophene) (RR-P3HT) (donors-D) and fullerene (PCBM) (acceptor-A) in an unprecedented broad spectral range of 0.25 to 2.5 eV. In D-A blends with maximum domain separation, such as RR-P3HT/PCBM, with (1.2:1) weight ratio having solar cell power conversion efficiency of ~4%, we found that although the intrachain excitons in the polymer domains decay within ~10 ps, no charge polarons are generated at their expense up to ~1 ns. Instead, there is a build-up of charge-transfer (CT) excitons at the D-A interfaces having the same kinetics as the exciton decay. The CT excitons dissociate into separate polarons in the D and A domains at a later time (>1 ns). This “two-step” charge photogeneration process may be typical in organic bulk heterojunction cells. We also report the effect of adding spin 1/2 radicals, Galvinoxyl on the ultrafast photoexcitation dynamics in annealed films of RR-P3HT/PCBM blend. The addition of Galvinoxyl radicals to the blend reduces the geminate recombination rate of photogenerated CT excitons. In addition, the photoexcitation dynamics in a new D-A blend of RR-P3HT/Indene C60 trisadduct (ICTA) has been studied and compared with the dynamics in RR-P3HT/PCBM.
- Research Organization:
- Univ. of Utah, Salt Lake City, UT (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
- Grant/Contract Number:
- FG02-04ER46109
- OSTI ID:
- 1628437
- Journal Information:
- Materials, Vol. 6, Issue 3; ISSN 1996-1944
- Publisher:
- MDPICopyright Statement
- Country of Publication:
- United States
- Language:
- English
Microstructure Formation of Functional Polymers by Evaporative Self-Assembly under Flexible Geometric Confinement
|
journal | March 2018 |
Directional charge separation in isolated organic semiconductor crystalline nanowires
|
journal | February 2016 |
Similar Records
High open-circuit voltage small-molecule p-DTS(FBTTh 2 )2.ICBA bulk heterojunction solar cells – morphology, excited-state dynamics, and photovoltaic performance
Monitoring the dynamics of miscible P3HT:PCBM blends: A quasi elastic neutron scattering study of organic photovoltaic active layers