Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Polymers: One stone, two birds

17.11.2011
A single polymer can be used to fabricate both thin-film transistors and solar cells

Polymers are the material of choice for making thin-film transistors and solar cells. They are also potentially suitable for manufacture using economical, high-throughput techniques, such as roll-to-roll and inkjet printing processes. However, transistors and solar cells have traditionally used different kinds of polymers, and this can severely complicate the fabrication process. Zhi-Kuan Chen at the A*STAR Institute of Materials Research and Engineering and co-workers have now developed a versatile polymer that is suitable for both kinds of devices.

Polymers with high-charge mobilities are ideal to use in the manufacture of transistors. However, these materials are susceptible to having large energy bandgaps, which prevent them from absorbing portions of the solar spectrum. Such materials could severely hamper the energy conversion efficiency if made into solar cells.

The researchers focused on a class of polymers called polythiophenes, derivatives of which have been measured to have high hole (or positive charge) mobilities. However, polythiophenes also have a large energy bandgap, which prevents them from absorbing light with red-orange wavelengths longer than 650 nm, thus reducing solar cell performance.

Previous work by other researchers has shown that this bandgap can be lowered by making modifications to the backbone of the polythiophene chain with groups of atoms that are able to accept charge. Even so, the power conversion efficiency of the resulting solar cells was below 2.3%, less than half of the best-performing polymer cells.

Chen and co-workers followed in the steps of their predecessors by modifying a polythiophene polymer. The result was a novel polymer called POD2T-DTBT that was measured to have a relatively low bandgap which resulted in an optical absorption range that extended to red-orange wavelengths of 780 nm, thus taking in more of the solar spectrum. At the same time, the hole mobility of the polymer was measured to be 0.20 cm2 per volt per second, comparable to unmodified polythiophene. This allowed for fabrication of high-performance transistors and solar cells. In particular, by combining POD2T-DTBT with the ester PC71BM, the research team constructed a solar cell with a power conversion efficiency of 6.26%, comparable to the efficiency of the best polymer cells to date.

This strong performance was drawn in part from the morphology of the thin films that resulted from the POD2T-DTBT / PC71BM mixture. Electron microscopy of the films showed that the two components were intimately mixed together: the long white fibers, which are 20–25 nm in width, correspond to the polymer, and the darker domains correspond to the ester (see image). The high-charge mobility of the POD2T-DTBT polymer itself also boosted performance.

References

Ong, K.-H. et al. A versatile low bandgap polymer for air-stable, high-mobility field-effect transistors and efficient polymer solar cells. Advanced Materials 23, 1409–1413 (2011).

Lee Swee Heng | Research asia research news
Further information:
http://www.a-star.edu.sg/
http://www.researchsea.com

More articles from Materials Sciences:

nachricht Crystal with a twist: Scientists grow spiraling new material
21.06.2019 | University of California - Berkeley

nachricht A new manufacturing process for aluminum alloys
19.06.2019 | DOE/Pacific Northwest National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fraunhofer IDMT demonstrates its method for acoustic quality inspection at »Sensor+Test 2019« in Nürnberg

From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.

Reducing machine downtime, manufacturing defects, and excessive scrap

Im Focus: Successfully Tested in Praxis: Bidirectional Sensor Technology Optimizes Laser Material Deposition

The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.

Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

Cooling with the sun

25.06.2019 | Power and Electrical Engineering

Robocabs: The mobility of the future?

25.06.2019 | Studies and Analyses

Skipping Meat on Occasion May Protect Against Type 2 Diabetes

25.06.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>