A huge market is developing for small disposable electronic devices, ranging from security tags to point-of-care diagnostics. Many of these devices require a power source, and photovoltaic devices (solar cells) are an attractive option.
However, the expense of preparing and processing inorganic semiconductors used in traditional solar cells precludes their use in such applications. Organic photovoltaic devices, meanwhile have great potential in this area; they are relatively easy to prepare and can be processed by simple techniques such as inkjet printing.
Organic photovoltaic devices contain both electron donors, which release an electron when irradiated, and electron acceptors, which complete the circuit necessary to convert light energy into electrical energy. However, mixtures of typical electron donors such as ð-conjugated oligomers—short chains of repeated, unsaturated, organic molecules, with alternating double and single bonds—and electron acceptors, such as C60 (buckminsterfullerene), have a tendency to form alternating stacks that results in lower efficiency. A partial solution is to directly attach the electron donor to the electron acceptor by a covalent bond and have both in a single molecule, but it is still important to have control over how the molecules pack together.
Now, a team of Japanese researchers including Takuzo Aida from the University of Tokyo and Masaki Takata from the RIKEN SPring-8 Center in Harima have designed liquid crystals—a phase that flows like a liquid but has short-range order between the molecules—that spontaneously assemble to form a donor-acceptor array (1). “It’s important to form separated columns or layers of the donors and acceptors, and to make a large contact area between them,” explains Yohei Yamamoto, another member of the team from the Japan Science and Technology Agency in Tokyo.
The molecules they designed feature a fullerene—the electron acceptor—at one end and a thiophene oligomer—the electron donor—at the other. A hydrophobic, or water-repellent, tail is attached to the donor end and a hydrophilic, or water-loving, tail is attached to the acceptor end. This functionalization ensures that the molecules of the liquid crystal line up to produce ordered layers of donors and acceptors and results in efficient photovoltaic behavior. “The liquid characteristics are useful as well,” notes Yamamoto, “the devices are self-healing as defects in the layer structure can be repaired by a simple heating and cooling process.” The design principles developed in this work should lead to the development of high-efficiency organic photovoltaic devices.
(1) Li, W.-S., Yamamoto, Y., Fukushima, T., Saeki, A., Seki, S., Tagawa, S., Masunaga, H., Sasaki, S., Takata, M. & Aida, T. Amphiphilic molecular design as a rational strategy for tailoring bicontinuous electron donor and acceptor arrays: photoconductive liquid crystalline oligothiophene–C60 dyads. Journal of the American Chemical Society 130, 8886–8887 (2008).
The corresponding author for this highlight is based at the RIKEN Structural Materials Science Laboratory
New method increases energy density in lithium batteries
24.10.2016 | Columbia University School of Engineering and Applied Science
'Super yeast' has the power to improve economics of biofuels
18.10.2016 | University of Wisconsin-Madison
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Physics and Astronomy
25.10.2016 | Life Sciences