From Organic Crystals “in the Rough” to “Prized” Semiconducting Thin Films

Leica digital and stereo microscopes are helping researchers to make progress in nanoscale electronics. They use them to:

- observe the synthesis process of organic, semiconducting crystals;

- screen the crystals to find those of the best quality; and

- prepare thin films from the crystals in order to measure their conductivity.

The goal of the research is to make it possible one day that nanoscale electronics are routinely exploited for many electronic devices.

Organic electronics, made from carbon-based molecules and polymers rather than metals and silicon, can be used for the production of inexpensive, flexible, ultralight electronic devices. One current application is the production of displays for televisions, monitors, smart phones, and tablets using organic light emitting diode (OLED) technology.

Many organic electronic devices use thin films of an organic, semiconducting material. Their structure and electrical conductivity are important properties which influence the performance.

One research group which has a strong interest in organic electronics is that of Prof. Hiroshi Yamamoto at the Institute for Molecular Science in Okazaki, Japan. The group has developed semiconducting organic crystals to produce Mott field-effect transistors (FETs) and electronic ferroelectric organic materials. Potential applications are for memory and computing devices.

Prof. Yamamoto’s group puts a lot of effort into studying the organic crystal growth process. They use a DMS digital microscope with additional software to take time-lapse micrographs. The microscope is set up on a swingarm stand which makes observation inside the crystal growth device more practical. By understanding the growth process in more detail, it can be better optimized so crystals with ever better semiconducting properties are produced.

Organic crystal growth chamber setup in the Yamamoto laboratory. Time-lapse observation during the growth process is possible using a DMS digital microscope from Leica Microsystems.

To make thin films, crystals of the best quality are selected. They are chosen via their shape and presence of any defects. For this crystal inspection process, the Yamamoto group uses a EZ4 stereo microscope with integrated camera. In addition, the microscope is used to place gold lead wires onto the thin films, in order to measure the conductivity. Such a microscope with a stand-alone camera enables the researchers to record high quality micrographs without a computer, more easily share results, and train new group members.

With the progress being made in organic, nanoscale electronics, one day we may find it in many devices used daily.

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