Substituent position-induced color tunability in polymer light-emitting diodes based on polyp-phenylene vinylene) derivatives

Abstract

We report substituent position-induced color tunability in polymer light-emitting diodes fabricated with polyp-phenylene vinylene) derivatives. When the position of the substituent in DMOP-PPV changes to the ortho, meta, and para site, the corresponding photo- and electro-luminescence spectra shift their peaks to a longer wavelength from 540 to 585 run. We ascribe this to the different degree of steric effect for each substituent position. As the substituent position is closer to the main chain, the effective conjugated length is reduced by the increased steric hindrance and the pi - pi* energy gap is broadened.