Researchers at Tokyo Institute of Technology (Tokyo Tech) report a unipolar n-type transistor with a world-leading electron mobility performance of up to 7.16 cm2 V-1 s-1. This achievement heralds an exciting future for organic electronics, including the development of innovative flexible displays and wearable technologies.
Researchers worldwide are on the hunt for novel materials that can improve the performance of basic components required to develop organic electronics.
Now, a research team at Tokyo Tech’s Department of Materials Science and Engineering including Tsuyoshi Michinobu and Yang Wang report a way of increasing the electron mobility of semiconducting polymers, which have previously proven difficult to optimize. Their high-performance material achieves an electron mobility of 7.16 cm2 V-1 s-1, representing more than a 40 percent increase over previous comparable results.
In their study published in the Journal of the American Chemical Society, they focused on enhancing the performance of materials known as n-type semiconducting polymers. These n-type (negative) materials are electron dominant, in contrast to p-type (positive) materials that are hole dominant. “As negatively-charged radicals are intrinsically unstable compared to those that are positively charged, producing stable n-type semiconducting polymers has been a major challenge in organic electronics,” Michinobu explains.
The research therefore addresses both a fundamental challenge and a practical need. Wang notes that many organic solar cells, for example, are made from p-type semiconducting polymers and n-type fullerene derivatives. The drawback is that the latter are costly, difficult to synthesize and incompatible with flexible devices. “To overcome these disadvantages,” he says, “high-performance n-type semiconducting polymers are highly desired to advance research on all-polymer solar cells.”
The team’s method involved using a series of new poly(benzothiadiazole-naphthalenediimide) derivatives and fine-tuning the material’s backbone conformation. This was made possible by the introduction of vinylene bridges capable of forming hydrogen bonds with neighboring fluorine and oxygen atoms. Introducing these vinylene bridges required a technical feat so as to optimize the reaction conditions.
Overall, the resultant material had an improved molecular packaging order and greater strength, which contributed to the increased electron mobility.
Using techniques such as grazing-incidence wide-angle X-ray scattering (GIWAXS), the researchers confirmed that they achieved an extremely short ?-? stacking distance of only 3.40 angstrom. “This value is among the shortest for high mobility organic semiconducting polymers,” says Michinobu.
There are several remaining challenges. “We need to further optimize the backbone structure,” he continues. “At the same time, side chain groups also play a significant role in determining the crystallinity and packing orientation of semiconducting polymers. We still have room for improvement.”
Wang points out that the lowest unoccupied molecular orbital (LUMO) levels were located at -3.8 to -3.9 eV for the reported polymers. “As deeper LUMO levels lead to faster and more stable electron transport, further designs that introduce sp2-N, fluorine and chlorine atoms, for example, could help achieve even deeper LUMO levels,” he says.
In future, the researchers will also aim to improve the air stability of n-channel transistors — a crucial issue for realizing practical applications that would include complementary metal-oxide-semiconductor (CMOS)-like logic circuits, all-polymer solar cells, organic photodetectors and organic thermoelectrics.
The Latest on: Organic electronics
via Google News
The Latest on: Organic electronics
- Are Perovskite LEDs an Up-and-Comer on the Display Scene?on April 7, 2020 at 2:40 pm
But what about perovskite LEDs? Can a team of researchers make them a viable alternative to organic LEDs or quantum-dot LEDs? Perovskite is a semiconductor material consisting of calcium and titanium ...
- New Solution Processing Methods for Organic Electronic Deviceson April 7, 2020 at 8:59 am
The field of organic electronics has seen a lot of interest in recent years. On the whole, the performance and efficiency of organic electronic devices are not typically as high as inorganic-based ...
- Organic Electronics Market May Set New Growth Story | BASF, Evonik, H.C. Starckon March 28, 2020 at 2:50 am
The latest release from HTF MI highlights the key market trends impacting the growth of the Global Organic Electronics market. The study highlights influencing factors that are impacting or ...
- Quantum phenomenon governs organic solar cellson March 26, 2020 at 9:46 am
Olle Inganäs, professor emeritus in the Division of Biomolecular and Organic Electronics asked him to repeat the experiment to eliminate the possibility of measurement errors. Time after time, and in ...
- Breath figure–derived porous semiconducting films for organic electronicson March 25, 2020 at 12:17 pm
2 School of Physics and Electronics, Henan University ... Here, we report the nature-inspired fabrication of several porous organic semiconductor-insulator blend films [semiconductor: P3HT (p-type ...
- Creating stretchable thermoelectric generatorson March 24, 2020 at 9:25 am
The breakthrough was enabled by a new composite material that may have widespread use in smart clothing, wearable electronics and electronic skin. Researchers at the Laboratory of Organic ...
- Universal three-dimensional crosslinker for all-photopatterned electronicson March 23, 2020 at 3:13 am
All-solution processing of large-area organic electronics requires multiple steps of patterning and stacking of various device components. Here, we report the fabrication of highly integrated ...
- The ink of the future in printed electronicson March 9, 2020 at 9:00 am
A research group led by Simone Fabiano at the Laboratory of Organic Electronics, Linköping University, has created an organic material with superb conductivity that doesn't need to be doped.
via Bing News