New patterning method for light emitting polymer

Abstract

We have patterned light emitting polymer from halo-precursor PPV [2,5-Bis(dimethyl-phenylsilyl)-1,4-bis(bromomethyl)benzene](BDMPS-PPV) and using the photobase generator(PBG) [{[(2,6-dinitrobenzyl)oxy]carbonyl}diphenylamine] through the photo-lithographic method by dehydrohalogenation reaction (E2 elimination reaction) and have successfully fabricated LEDs composed of patterned emissive layer (pattern resolution 10~30㎛). Used organic soluble halo-precursor BDMPS-PPV was synthesized through Gilch reaction under condition of 0.9 equivalent strong base. The device (configuration: ITO/ PEDOT:PSS /Polymer/Ca:Al) with photopatternable polymer by PBG showed better EL performances (lower turn-on voltage, higher maximum brightness, and EL efficiency) in contrast to behavior of LED through conventional thermal elimination methods. Based on experimently identified results, we could guess that the residual generated base may play the role of hole-transporting material, which influenced the enhanced electrical properties compared to thermally eliminated polymer. Also we have obtained the similar results of optical and electrical properties from UV exposed mixture with halo-precursor polymer and diphenylamine . We expect that this method will have several benefits for fabricating the device; in particular, the halo-precursor vinyl polymer can be simply patterned by the above method. Therefore, this photolithographic method is a potentially useful new technique for PLED fabrication in the market from microdisplay to large flat-panel display.