Significant Lowering Optical Loss of Electrodes via using Conjugated Polyelectrolytes Interlayer for Organic Laser in Electrically Driven Device Configuration

One of the challenges toward electrically driven organic lasers is the huge optical loss associated with the contact of electrodes and organic gain medium in device. We demonstrated a significant reduction of the optical loss by using our newly developed conjugated polyelectrolytes (CPE) PPFN(+)Br(−) as interlayer between gain medium and electrode. The optically pumped amplified spontaneous emission (ASE) was observed at very low threshold for PFO as optical gain medium and up to 37 nm thick CPE as interlayer in device configuration, c.f., a 5.7-fold ASE threshold reduction from pump energy 150 μJ/cm(2) for ITO/PFO to 26.3 μJ/cm(2) for ITO/PPFN(+)Br(−)/PFO. Furthermore, ASE narrowing displayed at pump energy up to 61.8 μJ/cm(2) for device ITO/PEDOT:PSS/PFO/PPFN(+)Br(−)/Ag, while no ASE was observed for the reference devices without CPE interlayer at pump energy up to 240 μJ/cm(2). The optically pumped lasing operation has also been achieved at threshold up to 45 μJ/cm(2) for one-dimensional distributed feedback laser fabricated on ITO etched grating in devices with CPE interlayer, demonstrating a promising device configuration for addressing the challenge of electrically driven organic lasers.