- Implication of Fluorine Atom on Electronic Properties, Ordering Structures, and Photovoltaic Performance in Naphthobisthiadiazole-Based Semiconducting Polymers
-
The development of semiconducting polymers is imperative to improve the performance of polymer-based solar cells (PSCs). In this study, new semiconducting polymers based on naphtho[1,2-c:5,6-c′]bis[1,2,5]thiadiazole (NTz), PNTz4TF2 and PNTz4TF4, having 3,3′-difluoro-2,2′-bithiophene and 3,3′,4,4′-tetrafluoro-2,2′-bithiophene, respectively, are designed and synthesized. These polymers possess a deeper HOMO energy level than their counterpart, PNTz4T, which results in higher open-circuit voltages in solar cells. This concequently reduces the photon energy loss that is one of the most important issues surrounding PSCs. The PNTz4TF4 cell exhibits up to 6.5% power conversion efficiency (PCE), whereas the PNTz4TF2 cell demonstrates outstanding device performance with as high as 10.5% PCE, which is quite high for PSCs. We further discuss the performances of the PSCs based on these polymers by correlating the charge generation and recombination dynamics with the polymer structure and ordering structure. We believe that the results provide new insights into the design of semiconducting polymers and that there is still much room for improvement of PSC efficiency.
- Kawashima, Kazuaki,Fukuhara, Tomohiro,Suda, Yousuke,Suzuki, Yasuhito,Koganezawa, Tomoyuki,Yoshida, Hiroyuki,Ohkita, Hideo,Osaka, Itaru,Takimiya, Kazuo
-
-
Read Online
- Fluorination of polythiophene derivatives for high performance organic photovoltaics
-
For the purpose of examining the tuning of photophysical property by fluorine atom substitution, fluorinated and nonfluorinated poly(3,4- dialkylterthiophenes) (PDATs) were synthesized, and their photovoltaic properties were compared. Fluorinated PDATs exhibit a deeper highest occupied molecular orbital energy level than nonfluorinated ones, leading to higher open-circuit voltage in organic solar cells and also enhanced molecular ordering as evidenced by a vibronic shoulder in UV-vis spectra, π-π scattering in GIWAXS, and a well-developed fibril structure in TEM, which contributes to efficient charge transport. As a result, the fluorine substitution increases the power conversion efficiency by 20% to 250% as compared with nonfluorinated PDATs.
- Jo, Jea Woong,Jung, Jae Woong,Wang, Hsin-Wei,Kim, Paul,Russell, Thomas P.,Jo, Won Ho
-
-
Read Online
- Pd-Catalyzed Aerobic Oxidative Coupling of Thiophenes: Synergistic Benefits of Phenanthroline Dione and a Cu Cocatalyst
-
Substituted bithiophenes are prominent fragments in functional organic materials, and they are ideally prepared via direct oxidative C-H/C-H coupling. Here, we report a novel PdII catalyst system, employing 1,10-phenanthroline-5,6-dione (phd) as the ancillary ligand, that enables aerobic oxidative homocoupling of 2-bromothiophenes and other related heterocycles. These observations represent the first use of phd to support Pd-catalyzed aerobic oxidation. The reaction also benefits from a Cu(OAc)2 cocatalyst, and mechanistic studies show that Cu promotes C-C coupling, implicating a role for CuII different from its conventional contribution to reoxidation of the Pd catalyst.
- Tereniak, Stephen J.,Bruns, David L.,Stahl, Shannon S.
-
supporting information
p. 20318 - 20323
(2020/12/01)
-
- Method for Aerobic Oxidative Coupling of Thiophenes with a Ligand-Supported Palladium Catalyst
-
An oxidative homocoupling method of synthesizing certain 2,2′-bithiophenes from thiophenes using oxygen as the terminal oxidant is disclosed. In non-limiting examples, the method uses oxygen along with a catalytic system that includes palladium, an assistive ligand, and a non-palladium metal additive to catalyze one of the following reactions: Associated catalytic systems and compositions are also disclosed.
- -
-
Paragraph 0095
(2019/07/23)
-