Related Experiment Video
Updated: Apr 17, 2026
08:29
Morphology Control for Fully Printable Organic–Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer
Published on: January 10, 2017
9.5K
A close look at charge generation in polymer:fullerene blends with microstructure control.
Mariateresa Scarongella1, Jelissa De Jonghe-Risse, Ester Buchaca-Domingo
1Institute of Chemical Sciences & Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) , SB ISIC GR-MO, Station 6, CH-1015 Lausanne, Switzerland.
Journal of the American Chemical Society
|February 5, 2015
Summary
Charge generation in polymer:fullerene blends is limited by exciton diffusion but accelerated in intermixed regions. Ultrafast hole migration from intermixed to neat domains prevents recombination in pBTTT:PCBM systems.
Area of Science:
- Materials Science
- Photovoltaics
- Organic Electronics
Background:
- Polymer:fullerene blends are crucial for organic solar cells.
- Understanding charge generation mechanisms is key to improving device efficiency.
- Microstructure control via additives influences blend performance.
Purpose of the Study:
- To elucidate charge generation mechanisms in pBTTT:PCBM blends.
- To investigate the role of microstructure and domain morphology.
- To understand exciton diffusion and charge separation dynamics.
Main Methods:
- Ultrafast transient absorption spectroscopy
- Electro-absorption (Stark effect) spectroscopy
- Fluorescence up-conversion spectroscopy
- Processing with fatty acid methyl ester additives
Main Results:
- Exciton diffusion in phase-pure domains limits charge transfer rates.
- Prompt charge separation occurs in molecularly intermixed regions (co-crystal phase).
- Neat domains are vital for preventing geminate recombination.
- Direct visualization of subpicosecond hole migration from intermixed to neat domains.
Conclusions:
- Molecular intermixing and neat domains are critical for efficient charge generation and separation.
- Ultrafast hole transport is facilitated by energy cascades and high local mobility.
- Controlling microstructure is essential for optimizing organic photovoltaic performance.
More Related Videos
Related Concept Videos
00:57Cationic Chain-Growth Polymerization: Mechanism
3.1K
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...
3.1K
01:04Anionic Chain-Growth Polymerization: Mechanism
2.6K
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael...
2.6K
01:20Anionic Chain-Growth Polymerization: Overview
2.8K
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
2.8K
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
4.4K
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
4.4K
01:14Polymer Classification: Architecture
4.2K
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
4.2K
01:17Radical Chain-Growth Polymerization: Chain Branching
2.7K
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
2.7K