Abstract: Provided are a method for preparing a pixel defining layer comprising applying and coating, pre-baking, exposing to light, developing, and post-baking of a photosensitive composition containing a colorant having a pigment with an average particle size of 100 nm or less, wherein the coated film generated after the post-baking has an optical density of 0.8/?m to 2.0/?m, a roughness of 3.0 nm or less, and no residue; and an organic light emitting display device comprising the pixel defining layer obtained by the method which has improved display reliability and lifetime as well as vivid colors.

Abstract: An object of the present disclosure is to improve display reliability and lifetime as well as vivid colors. When there remain residues in the washing part due to incomplete removal during the developing step, it can cause dark spots or pixel off due to the residues, and thus residue-free pixels can be formed by optimizing the temperature and time for developing. Additionally, when the amount of outgas in the panel after post-baking is 15 ppm or more, it may cause a reduction in luminance and lifetime due to pixel shrinkage. Therefore, in order to minimize the amount of outgas after completion of the post-baking process, the generation of outgas in the panel state can be minimized by generating sufficient fume in the post-baking step, in addition to forming clean pixels in the developing step.