Tag Archives: Michael Grätzel

Could your photo be a solar cell?

Scientists at Aalto University (Finland) have found a way to print photographs that produce energy (like a solar cell does) according to a July 25, 2016 news item on Nanowerk,

Solar cells have been manufactured already for a long from inexpensive materials with different printing techniques. Especially organic solar cells and dye-sensitized solar cells are suitable for printing.

“We wanted to take the idea of printed solar cells even further, and see if their materials could be inkjet-printed as pictures and text like traditional printing inks,” tells University Lecturer Janne Halme.

A semi-transparent dye-sensitized solar cell with inkjet-printed photovoltaic portraits of the Aalto researchers (Ghufran Hashmi, Merve Özkan, Janne Halme) and a QR code that links to the original research paper. Courtesy: Aalto University

A semi-transparent dye-sensitized solar cell with inkjet-printed photovoltaic portraits of the Aalto researchers (Ghufran Hashmi, Merve Özkan, Janne Halme) and a QR code that links to the original research paper. Courtesy: Aalto University

A July 26, 2016 Aalto University press release, which originated the news item, describes the innovation in more detail,

When light is absorbed in an ordinary ink, it generates heat. A photovoltaic ink, however, coverts part of that energy to electricity. The darker the color, the more electricity is produced, because the human eye is most sensitive to that part of the solar radiation spectrum which has highest energy density. The most efficient solar cell is therefore pitch-black.

The idea of a colorful, patterned solar cell is to combine also other properties that take advantage of light on the same surface, such as visual information and graphics.

– For example, installed on a sufficiently low-power electrical device, this kind of solar cell could be part of its visual design, and at the same time produce energy for its needs, ponders Halme.

With inkjet printing, the photovoltaic dye could be printed to a shape determined by a selected image file, and the darkness and transparency of the different parts of the image could be adjusted accurately.

– The inkjet-dyed solar cells were as efficient and durable as the corresponding solar cells prepared in a traditional way. They endured more than one thousand hours of continuous light and heat stress without any signs of performance degradation, says Postdoctoral Researcher Ghufran Hashmi.

The dye and electrolyte that turned out to be best were obtained from the research group in the Swiss École Polytechnique Fédérale de Lausanne, where Dr. Hashmi worked as a visiting researcher.

– The most challenging thing was to find suitable solvent for the dye and the right jetting parameters that gave precise and uniform print quality, tells Doctoral Candidate Merve Özkan.

This puts solar cells (pun alert) in a whole new light.

Here’s a link to and a citation for the paper,

Dye-sensitized solar cells with inkjet-printed dyes by Syed Ghufran Hashmi, Merve Özkan, Janne Halme, Shaik Mohammed Zakeeruddin, Jouni Paltakari, Michael Grätzel, and Peter D. Lund. Energy Environ. Sci., 2016,9, 2453-2462 DOI: 10.1039/C6EE00826G First published online 09 Jun 2016

This paper is behind a paywall.

Institute for Electrical and Electronics Engineers’ (IEEE) Nano 2015 conference call for papers

The institute for Electrical and Electronics Engineers is holding its Nano 2015 conference in Rome, Italy from July 27 – 30, 2015. This is the second call for papers (I missed the first call),

We invite you to submit papers, proposals for tutorials, workshops to the International IEEE Conference on Nanotechnology which will be held in Rome, July 27-30, 2015. (See www.ieeenano15.org). The dead-line for abstract submission is 15th March 2015.

This conference is the 15th edition of the flagship annual event of the IEEE Nanotechnology Council. IEEE NANO 2015 will provide an international forum for the exchange of technical information in a wide variety of branches of Nanotechnology and Nanoscience, through feature tutorials, workshops, track sessions and special sessions; plenary and invited talks from the most renowned scientists and engineers; exhibition of software, hardware, equipment, materials, services and literature. With its fantastic setting in the centre of the Eternal City, at a walking distance from Colosseum and from the most exciting locations of ancient Rome, IEEE NANO 2015 will provide a perfect forum for inspiration, interactions and exchange of ideas.

All accepted papers will be published by IEEE Press, included in IEEE Xplore and Indexed by EI. Selected conference papers will be considered for publication on IEEE Transactions on Nanotechnology.

Important Dates

March 15, 2015:       Tutorial/Workshop Proposal
March 15, 2015:        Abstract Submission
April 15, 2015:           Acceptance Notification

May 15, 2015:            Full Paper Submission
June 1, 2015:              End of early Registration

Topics for contributing papers include but are not limited to:

Nanosensors, Actuators
Smart systems
Graphene-Based Materials
Nano-energy, Energy Harvesting
Nanobiology, Nanobiotechnology
Nano-optics, Nano-photonics
Nano-electromagnetics, NanoEMC
Nanofabrication, Nanoassemblies
Nanorobotics, Nanomanipulation
Multiscale Modeling and Simulation

PLENARY SPEAKERS (See www.ieeenano15.org/program/plenary-speakers)
George Bourianoff, Intel (USA)
Michael Grätzel, EPFL (Switzerland)
Roberto Cingolani, IIT (Italy)
Rodney Ruoff, NIST (Korea)
Takao Someya, Tokyo Univ. (Japan)
Theresa Mayer, Pennsylvania State Univ. (USA)
Zhong Lin Wang, Georgia Tech (USA)

1) Graphene
2) Nanoelectromagnetics and Nano-EMC
3) Nanometrology and device characterization
4) Nanotechnology for microwave and THz
5) Memristor
Part 1: Resistive switching: from fundamentals to production
Part 2: Memristive nanodevices and nanocircuits
6) Nanophononics
7) Drug Toxicity Mitigation. Nanotechnology-Enabled Strategies
8) Conformable Electronics and E-Skin
9) Organic Neurooptoelectronics

There are more details about the call in this PDF. Good luck!

Solar cells and ‘tinkertoys’

A Nov. 3, 2014 news item on Nanowerk features a project researchers hope will improve photovoltaic efficiency and make solar cells competitive with other sources of energy,

 Researchers at Sandia National Laboratories have received a $1.2 million award from the U.S. Department of Energy’s SunShot Initiative to develop a technique that they believe will significantly improve the efficiencies of photovoltaic materials and help make solar electricity cost-competitive with other sources of energy.

The work builds on Sandia’s recent successes with metal-organic framework (MOF) materials by combining them with dye-sensitized solar cells (DSSC).

“A lot of people are working with DSSCs, but we think our expertise with MOFs gives us a tool that others don’t have,” said Sandia’s Erik Spoerke, a materials scientist with a long history of solar cell exploration at the labs.

A Nov. 3, 2014 Sandia National Laboratories news release, which originated the news item, describes the project and the technology in more detail,

Sandia’s project is funded through SunShot’s Next Generation Photovoltaic Technologies III program, which sponsors projects that apply promising basic materials science that has been proven at the materials properties level to demonstrate photovoltaic conversion improvements to address or exceed SunShot goals.

The SunShot Initiative is a collaborative national effort that aggressively drives innovation with the aim of making solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, the Energy Department supports efforts by private companies, universities and national laboratories to drive down the cost of solar electricity to 6 cents per kilowatt-hour.

DSSCs provide basis for future advancements in solar electricity production

Dye-sensitized solar cells, invented in the 1980s, use dyes designed to efficiently absorb light in the solar spectrum. The dye is mated with a semiconductor, typically titanium dioxide, that facilitates conversion of the energy in the optically excited dye into usable electrical current.

DSSCs are considered a significant advancement in photovoltaic technology since they separate the various processes of generating current from a solar cell. Michael Grätzel, a professor at the École Polytechnique Fédérale de Lausanne in Switzerland, was awarded the 2010 Millennium Technology Prize for inventing the first high-efficiency DSSC.

“If you don’t have everything in the DSSC dependent on everything else, it’s a lot easier to optimize your photovoltaic device in the most flexible and effective way,” explained Sandia senior scientist Mark Allendorf. DSSCs, for example, can capture more of the sun’s energy than silicon-based solar cells by using varied or multiple dyes and also can use different molecular systems, Allendorf said.

“It becomes almost modular in terms of the cell’s components, all of which contribute to making electricity out of sunlight more efficiently,” said Spoerke.

MOFs’ structure, versatility and porosity help overcome DSSC limitations

Though a source of optimism for the solar research community, DSSCs possess certain challenges that the Sandia research team thinks can be overcome by combining them with MOFs.

Allendorf said researchers hope to use the ordered structure and versatile chemistry of MOFs to help the dyes in DSSCs absorb more solar light, which he says is a fundamental limit on their efficiency.

“Our hypothesis is that we can put a thin layer of MOF on top of the titanium dioxide, thus enabling us to order the dye in exactly the way we want it,” Allendorf explained. That, he said, should avoid the efficiency-decreasing problem of dye aggregation, since the dye would then be locked into the MOF’s crystalline structure.

MOFs are highly-ordered materials that also offer high levels of porosity, said Allendorf, a MOF expert and 29-year veteran of Sandia. He calls the materials “Tinkertoys for chemists” because of the ease with which new structures can be envisioned and assembled. [emphasis mine]

Allendorf said the unique porosity of MOFs will allow researchers to add a second dye, placed into the pores of the MOF, that will cover additional parts of the solar spectrum that weren’t covered with the initial dye. Finally, he and Spoerke are convinced that MOFs can help improve the overall electron charge and flow of the solar cell, which currently faces instability issues.

“Essentially, we believe MOFs can help to more effectively organize the electronic and nano-structure of the molecules in the solar cell,” said Spoerke. “This can go a long way toward improving the efficiency and stability of these assembled devices.”

In addition to the Sandia team, the project includes researchers at the University of Colorado-Boulder, particularly Steve George, an expert in a thin film technology known as atomic layer deposition.

The technique, said Spoerke, is important in that it offers a pathway for highly controlled materials chemistry with potentially low-cost manufacturing of the DSSC/MOF process.

“With the combination of MOFs, dye-sensitized solar cells and atomic layer deposition, we think we can figure out how to control all of the key cell interfaces and material elements in a way that’s never been done before,” said Spoerke. “That’s what makes this project exciting.”

Here’s a picture showing an early Tinkertoy set,

Original Tinkertoy, Giant Engineer #155. Questor Education Products Co., c.1950 [downloaded from http://en.wikipedia.org/wiki/Tinkertoy#mediaviewer/File:Tinkertoy_300126232168.JPG]

Original Tinkertoy, Giant Engineer #155. Questor Education Products Co., c.1950 [downloaded from http://en.wikipedia.org/wiki/Tinkertoy#mediaviewer/File:Tinkertoy_300126232168.JPG]

The Tinkertoy entry on Wikipedia has this,

The Tinkertoy Construction Set is a toy construction set for children. It was created in 1914—six years after the Frank Hornby’s Meccano sets—by Charles H. Pajeau and Robert Pettit and Gordon Tinker in Evanston, Illinois. Pajeau, a stonemason, designed the toy after seeing children play with sticks and empty spools of thread. He and Pettit set out to market a toy that would allow and inspire children to use their imaginations. At first, this did not go well, but after a year or two over a million were sold.

Shrinky Dinks, tinkertoys, Lego have all been mentioned here in conjunction with lab work. I’m always delighted to see scientists working with or using children’s toys as inspiration of one type or another.

There once was a champion … it was nano-rust

Swiss and Israeli scientists have discovered water and nano iron oxide (rust) can be used to produce solar hydrogen cheaply. From the July 7, 2013 news release on EurekAlert,

In the quest for the production of renewable and clean energy, photoelectrochemical cells (PECs) constitute a sort of a Holy Grail. PECs are devices able of splitting water molecules into hydrogen and oxygen in a single operation, thanks to solar radiation. “As a matter of fact, we’ve already discovered this precious chalice, says Michael Grätzel, Director of the Laboratory of Photonics and Interfaces (LPI) at EPFL [Ecole Polytechnique Fédérale de Lausanne] and inventor of dye-sensitized photoelectrochemical cells. Today we have just reached an important milestone on the path that will lead us forward to profitable industrial applications.”

This week, Nature Materials is indeed publishing a groundbreaking article on the subject. EPFL researchers, working with Avner Rotschild from Technion (Israel), have managed to accurately characterize the iron oxide nanostructures to be used in order to produce hydrogen at the lowest possible cost. “The whole point of our approach is to use an exceptionally abundant, stable and cheap material: rust,” adds Scott C. Warren, first author of the article.

The EFFL July 9, 2013 news release by Emmanuel Barraud about this research provides more details,

At the end of last year, Kevin Sivula, one of the collaborators at the LPI laboratory, presented a prototype electrode based on the same principle. Its efficiency was such that gas bubbles emerged as soon as it was under a light stimulus. Without a doubt, the potential of such cheap electrodes was demonstrated, even if there was still room for improvement.

By using transmission electron microscopy (TEM) techniques, researchers were able to precisely characterize the movement of the electrons through the cauliflower-looking nanostructures forming the iron oxide particles, laid on electrodes during the manufacturing process. “These measures have helped us understand the reason why we get performance differences depending on the electrodes manufacturing process”, says Grätzel.

By comparing several electrodes, whose manufacturing method is now mastered, scientists were able to identify the “champion” structure. A 10×10 cm prototype has been produced and its effectiveness is in line with expectations. The next step will be the development of the industrial process to large-scale manufacturing. A European funding and the Swiss federal government could provide support for this last part.

Evidently, the long-term goal is to produce hydrogen – the fuel of the future – in an environmentally friendly and especially competitive way. For Michael Grätzel, “current methods, in which a conventional photovoltaic cell is coupled to an electrolyzer for producing hydrogen, cost 15 € per kilo at their cheapest. We’re aiming at a € 5 charge per kilo”.

Here’s a link to and a citation for the published research paper,

Identifying champion nanostructures for solar water-splitting by Scott C. Warren, Kislon Voïtchovsky, Hen Dotan, Celine M. Leroy, Maurin Cornuz, Francesco Stellacci, Cécile Hébert, Avner Rothschild & Michael Grätzel. Nature Materials (2013) doi:10.1038/nmat3684
Published online 07 July 2013

This paper is behind a paywall.