Enhancing emission of poly(p-phenylenevinylene) by sandwiching an energy transferable layer

Abstract

Photoluminescent (PL) and electroluminescent (EL) efficiencies of poly(p-phenylenevinylene) (PPV) film were found to be significantly increased by sandwiching an energy-transferable poly(2-carboxyphenylene-1,4-diyl) (PCPD) layer. Energy transfer from PCPD to PPV in the prepared PPV/PCPD/PPV trilayer film was detected by photoluminescence excitation (PLE) spectroscopy and time-resolved fluorescence decay profiles, and was attributed to the chemical-interlocking between two polymers in the interfacial regions. It resulted in a strong increase of the PL intensity, a ∼250-times increase of the maximum external EL quantum efficiency (up to 1.3% photon/electron), and a ∼500-times increase of the maximum light output for the ITO/PPV/PCPD/PPV/Al device compared to the neat PPV. The significant increase of EL was also attributed to the higher energy bandgap of inserting PCPD layer that trap the holes and electrons in the interfacial regions, facilitating the formation of excitons in situ and energy transfer.