Improvement of MEH-PPV performance for laser and optoelectronic applications

One of the most promising emissive conjugated polymers that has diverse applications is Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The attractive attributes of this material are high quantum yield, light weight, strong absorption, possibility of depositing on flexible substrate and the use of low temperature. These attributes render this material to be used in various optoelectronics. However, MEH-PPV suffers from degradation and methods to overcome degradation for this material are of great interest. Here MEH-PPV has been used as an active laser material and it has been shown that sodium dodecyl sulfate is a very promising additive to overcome degradation for MEH-PPV laser. Optical properties (absorption coefficient, refractive index, and optical bandgap) of pristine MEH-PPV as well as a mixture of MEH-PPV and sodium dodecyl sulfate (SDS) dissolved in toluene have been reported. The addition of SDS stabilizer to MEH-PPV increases the refractive index and decreases the optical bandgap. Photoluminescence, input-output energy and photostability of both the pristine and mixture of MEH-PPV with SDS have been reported. Results show that the presence of SDS strongly improves the laser photostability of MEH-PPV. The evolution of the laser output energy reduces to 0.75 of its initial energy after 108,800 pulses in case of using SDS, whereas the output energy decreases to 0.75 of its initial energy after only 1400 pulses for the MEH-PPV pristine sample. Further, laser efficiency is also improved in the presence of SDS as it is 0.5% compared to 0.07% for pristine sample. The role of SDS stabilizer in improving laser performance of MEH-PPV has been discussed.