Photoluminescence of MEH-PPV Brushes, Pancakes, and Free Molecules in Solutions and Dry States

Photoluminescence (PL) of a conjugated polymer MEH-PPV, poly[2-methoxy-5-(2′-ethylhexyl)oxy)-1,4-phenylenevinylene], grafted on a silicon wafer with controlled tether spacing was studied to reveal the effects of molecular conformation, chain packing, and mechanical stress. In the solvent-swollen state, the PL of the densely grafted polymer (denoted “brushes”) was blue-shifted substantially relative to the lightly grafted (denoted “pancakes”) …