Flexible, portable and wearable electronic devices including displays, energy powers, logic circuits have been attracting great interest that could significantly change people’s lifestyles.
Organic or polymer semiconductors that comprise of carbon, hydrogen, oxygen and/or other atoms (sulfur, nitrogen etc.) are solution-processable, printable and can realize most of the optoelectronic devices (solar cells, light-emitting diodes, transistors, photodetectors etc.) that traditional semiconductors such as silicon, III-V compound can do.
Like in the traditional silicon semiconductors, doping is a very important strategy to change or tune the physical properties of the organic semiconductors, i.e. charge carrier density, mobility, and energy level. These properties significantly influence the performance of the corresponding optoelectronic devices, like organic light-emitting diodes, transistors, solar cells as well as recently perovskite-based electronic devices.
So far, solution-processed n-dopants that can significantly increase the electron concentration and shift up the Fermi level towards the lowest unoccupied molecular orbital (LUMO level) of n-type organic semiconductors are still few and highly desirable.
Here, Prof. Yinhua Zhou and co-workers from Huazhong University of Science and Technology report that an organic base 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) can act as a very effective n-dopant for the solution-processed electronic devices in their new publication in Advanced Functional Materials.
The DBU has been generally used in organic chemistry as a catalyst, a ligand, and a non-nucleophilic base. It can be purchased from many chemical vendors at a low cost. They open up its news application as a solution-processed dopant for new optoelectronic applications.
The researchers found the DBU could effectively dope many n-channel organic molecules or polymers, like fullerenes. The efficient charge transfer and doping are due to the strong its electron-donating property. They observed the DBU-doping changed the physical property of the fullerene acceptors (increasing the electrical conductivity and shifts the Fermi levels).
The DBU-doping enhanced the power conversion efficiency of the solar cells, increased the electron mobility and lower the threshold voltage PC61BM-based n-channel field-effect transistors.
This study, An Amidine-Type n-Dopant for Solution-Processed Field-Effect Transistors and Perovskite Solar Cells was recently published in the journal Advanced Functional Materials.