While it has been a rare feat to obtain white emission from single molecules, there are a few successful strategies such as excimer emission and excited-state intramolecular proton transfer, among others.
Sergei Tretiak, Hsing-Lin Wang, and colleagues, Los Alamos National Laboratory, NM, USA, harness the intermolecular charge transfer in an oligophenylene vinylene (OPV) derivative for white emission. Bearing an amine group across from a quaternary ammonium group at the conjugated OPV backbone, the dipole moment of the molecule changes upon the protonation/deprotonation of the amine group. This yields white light from red and blue emissions at pH 5.
The compound retains its tunable emission capability in thin films and LED devices. It can also be fabricated into blue-, white-, and orange-color LEDs simply using different processing conditions.
- A New pH Sensitive Fluorescent and White Light Emissive Material through Controlled Intermolecular Charge Transfer,
Youngil Park, Olena Postupna, Andriy Zhugayevych, Hwangyu Shin, Young-Shin Park, Beomjin Kim, Hung-Ju Yen, Pradeep Cheruku, Jennifer S Martinez, Jongwook Park, Sergei Tretiak, Hsing-Ling Wang,
Chem. Sci. 2014.