The efficient conversion of light into electrical signals is of central importance for electronic imaging, optical communication technologies and biomedical sensor technology. In cooperation with Chinese partners, researchers at Münster University (WWU) have developed a novel concept for molecular phototransistors to convert light into electrical signals with unprecedented efficiency.
Phototransistors are important components in optoelectronics for converting light into electrical signals. Organic phototransistors (OFT) are of particular practical interest for the development of flexible and foldable electronic components. In addition to their mechanical flexibility, they are lightweight, inexpensive and relatively easy to produce over a large area.
By the targeted modification of the molecular structure, the physical properties can be precisely adjusted over a wide range. The developments of organic OFT known so far have always lagged behind those of inorganic or hybrid systems in terms of their performance. The main reason for this lies in the low mobility of the charge carriers in organic photo-responsive materials.
The new approach is based on the use of small molecules instead of long polymer chains. These molecules - 2, 6-diphenylanthracene (DPA), tob e exact, - have a strongly fluorescent anthracene unit as semiconducting nucleus and phenyl groups, which optimize charge carrier mobility and opto-electronic properties. The phototransistors produced in this way, consisting of no molecules, exhibit high photosensitivity, photo-responsiveness and detectivity. "The values achieved outperform those of all other known OFTs and are among the best of all known phototransistors to date, including inorganic ones in many areas," explains Dr. Deyang Ji, who manufactured the new phototransistors at the Institute of Physics at WWU . Saeed Amirjalyer, group leader at CeNTech adds: "By combining the experimental data with simulations, we were able to quantitatively understand the high performance data of the developed phototransistors. This enables targeted optimization with the goal of future commercialization.
The suitable selection of organic molecules and basic physical research have thus made it possible to build an important