November 20, 2019
Organic semiconductors are an attractive technology. They enable the inexpensive production of solar cells, sensors or LEDs, for example. However, their efficiency and service life are lower than those of inorganic semiconductors. Improving their properties is a goal of Dr. Supriya Ghosh, who, as a fellow of the renowned Humboldt Foundation, will spend two years researching at Jacobs University in the research group of Dr. Arnulf Materny, Professor of Chemical Physics.
Organic semiconductors have nothing to do with living organisms. The term refers to organic chemistry, the branch of chemistry that deals with carbon compounds. While classical semiconductors are made of inorganic materials such as gallium or silicon, organic semiconductors are based on these organic compounds. What is specially exciting is that organic semiconductors can be produced very cheaply, for example whole components can be printed.
The efficiency of organic semiconductors depends on the creation and transport of charges. These are electrons and positive holes that are created when the electrons have left their position. When a semiconductor, such as a solar cell, is stimulated by light, "electron-hole pairs" are formed. These can separate and thus generate charges, but they can also reunite, causing charges to be lost. A better understanding of these processes, which can be very complex and often involve several intermediate steps, is important to improve semiconductors.
One of the most interesting areas of semiconductor devices is the interface between semiconductor and metal electrode. The processes here are of ultrafast dynamics, but they can be observed with the femtosecond laser spectroscopy available at Jacobs University in Prof. Materny's laboratory. A femtosecond is an unimaginably short unit of time, corresponding to the millionth part of a billionth of a second. While light can reach the moon in about one second, it covers a distance not even the width of a hair in 100 femtoseconds –that's how long typical laser pulses used for the experiments are.
It was the special working conditions at Jacobs University and the expertise of Prof. Materny that brought Dr. Supriya Ghosh to Bremen. "Here I have the opportunity to expand my skills in dealing with various time-resolved spectroscopic and microscopic techniques," says the chemist, who recently did research at the Indian Institute of Technology (IIT) in Mandi, Himachal Pradesh, India.
The Alexander von Humboldt Foundation supports intercultural dialogue between German and foreign scientists through academic exchange. The fellowships are highly regarded. Every year, the Humboldt Foundation enables 500 Postdocs from all over the world to spend a scientific stay in Germany. The Foundation maintains a network of more than 29.000 Humboldtians from all disciplines in over 140 countries worldwide – including 55 Nobel Prize winners.