In order to increase the conductivity of polymers — and in this way obtain higher efficiency in organic solar cells, light-emitting diodes, and other bioelectronic applications — researchers previously doped the material with various substances. Typically, this is done by either removing an electron or donating it to the semiconductor material with a dopant molecule, a strategy that increases the number of charges and thereby the conductivity of the material. The process is stable for a while but the material degenerates and the substances used as doping agents can eventually leach out.
Researchers have succeeded in combining the two polymers, producing a conducting ink that does not require any doping to conduct electricity. The energy levels of the two materials perfectly match, such that charges are spontaneously transferred from one polymer to the other.
The phenomenon of spontaneous charge transfer has been demonstrated before but only for single crystals on a laboratory scale. Polymers consist of large and stable molecules that are easy to deposit from solution, which is why they are well suited for large-scale use as ink in printed electronics.
Polymers are simple and relatively cheap materials and are commercially available. No foreign substances leach out from the new polymer mixture. It remains stable for a long time and withstands high temperatures. These properties are important for energy harvesting/storage devices as well as wearable electronics.