Degrading dopants could enhance semiconductor performance

Organic semiconductors are carbon-based materials that can conduct electricity, and can be used for flexible, lightweight and potentially low-cost electronic devices. While the technology is promising, performance challenges remain.

Electric conductivity requires doping, a process of adding mobile electrical charges to the material. Conventional chemical dopants eventually reach a limit, restricting how many charges they can create.

In a study published in the journal Nature Materials, researchers at Concordia University outlined a way around that limit. Their research shows that allowing a chemical dopant to break down after transferring an electron can keep the doping process going, producing much higher concentrations of electrical charges.

The researchers call the process “degradation-assisted doping” (DAD). To understand how it works, they combined computer simulations with laboratory experiments using the organic semiconductor P3HT and a chemical compound called tris(pentafluorophenyl)borane, or BCF.

They used several techniques, including nuclear magnetic resonance, optical spectroscopy, electron paramagnetic resonance and calorimetry, to track what happened after BCF transferred an electron to P3HT. Computer modelling was used to examine the chemical reactions involved.

The results showed that BCF breaks down after accepting an electron, removing its reaction products from the process and allowing additional electrons to be transferred. The researchers found that the new method can create up to 100 times more mobile electrical charges in the semiconductor than conventional doping, potentially making the material much more conductive. BCF also produced higher conductivity in P3HT than other commonly used dopants.

The authors believe the findings establish DAD as a new strategy for improving the performance of organic semiconductors and could help researchers design more efficient materials for flexible electronics, optoelectronic devices and thermoelectric technologies.

Image credit: iStock.com/nazar_ab