Suppression of electron trapping by quantum dot emitters using a grafted polystyrene shell

A fundamental problem of adding chromophores to an organic host is that their smaller band gap leads to severe trapping of either electrons or holes, resulting in strongly unbalanced transport. We demonstrate that electron trapping by an inorganic quantum dot (QD) in a conjugated polymer host can be suppressed by functionalizing its shell with a thin insulating polystyrene layer. The polystyrene shell not only reduces trapping, but also suppresses detrapping of captured electrons, resulting in increased charging of the QDs with subsequent voltage scans, after initial charging, a red-emitting hybrid polymer:QD light-emitting diode is obtained with voltage independent electroluminescence spec…

Monitoring of Cell Layer Integrity with a Current-Driven Organic Electrochemical Transistor

Abstract The integrity of CaCo-2 cell barriers is investigated by organic electrochemical transistors (OECTs) in a current-driven configuration. Ion transport through cellular barriers via the paracellular pathway is modulated by tight junctions between adjacent cells. Rupturing its integrity by H2O2 is monitored by the change of the output voltage in the transfer characteristics. It is demonstrated that by operating the OECT in a current-driven configuration, the sensitive and temporal resolution for monitoring the cell barrier integrity is strongly enhanced as compared to the OECT transient response measurement. As a result, current-driven OECTs are useful tools to assess dynamic and crit…

Current-Driven Organic Electrochemical Transistors for Monitoring Cell Layer Integrity with Enhanced Sensitivity

In this progress report an overview is given on the use of the organic electrochemical transistor (OECT) as a biosensor for impedance sensing of cell layers. The transient OECT current can be used to detect changes in the impedance of the cell layer, as shown by Jimison et al. To circumvent the application of a high gate bias and preventing electrolysis of the electrolyte, in case of small impedance variations, an alternative measuring technique based on an OECT in a current-driven configuration is developed. The ion-sensitivity is larger than 1200 mV V-1 dec-1 at low operating voltage. It can be even further enhanced using an OECT based complementary amplifier, which consists of a p-type a…

Monitoring Reversible Tight Junction Modulation with a Current-Driven Organic Electrochemical Transistor