Abstract
We proposed the use of light-emitting electrochemical cells (LECs) to demonstrate polymer injection
lasers. We demonstrated optically pumped amplified spontaneous emission (ASE) in the active layer of
LECs by a blend of a polymer and an ionic liquid. Using ionic liquid enabled the film blend to maintain
a high degree of transparency with the flat surface, resulting in film as an optical slab waveguide that
achieved a low ASE threshold energy of 4 μJ/cm2. A planar LEC based on the polymer:ionic liquid
blend showed a fast turn-on, a bright linear shape emission in the middle of the two contacts, and a high
current density over 1 kA/cm2 using a pulse driving technique. Furthermore, the application of short
voltage pulses of 200 ns successfully avoided an efficiency roll off, which is a critical issue for laser
oscillation by electrical excitation under high current density.
