Complete Suppression of Blinking and Reduced Photobleaching in Single MEH-PPV Chains in Solution

We report photophysical properties of individual chains of the conjugated polymer MEH-PPV in a concentrated solution of polystyrene. MEH-PPV chains diffusing freely in the solution show no fluorescence blinking and reduced photobleaching. Adsorption of the chains onto a substrate in the solution leads to 34% decrease in fluorescence intensity (quantum efficiency), fivefold increase in the rate of photobleaching and appearance of blinking. The blinking is often a two-state process caused by a reversible interaction with a single quencher. The interaction causes quenching of a substantial length of the extended MEH-PPV chain.