Efficient full-spectrum white polymer light-emitting diodes by plasma polymerization

Abstract

Efficient full-spectrum white polymer light- emitting diodes (WPLEDs) were fabricated using single- layer luminescent polymer produced by one-step plasma polymerization from naphthalene (PEN) (and carbazole (PENCB)) derivatives. WPLEDs based on the plasma polymers had demonstrated efficient pure white light electroluminescence that covers the full visible spectral range with excellent color stability. A new monomer injection method enables excellent structural retention and excellent device reproducibility. Monomers of good luminescent quality and charge transport behavior can be selected to synthesize the light-emitting polymer without considering their individual chemical behaviors. It provides an opportunity of one-step reaction with molecularly smooth, pinhole free and high quality films. Full- spectrum electroluminescence (EL) emission was originated f rom molecular excitons, intermolecular excimers and electromers. It was produced pure stable white light emission at CIE coordinates of (0.33,0.34). Excellent luminance efficiency of 9.8 cd/A and a power efficiency of 2.1 lm/W were obtained. The efficiency reported here was based on films and devices not yet optimized. This new method merits further study as it manifests great potentials for simplifying the WPLEDs proce ss to enable a new type of high efficient, low-cost, and large- area-compatible processes.