A method for forming a pixel-defining layer on an OLED panel comprises the following steps: (A) providing a substrate; (B) forming a plurality of first electrodes in parallel stripes on the substrate; (C) coating a layer of non-photosensitive polyimide or polyimide precursor compositions on the substrate; (D) first prebaking said substrate; (E) coating a layer of photoresist compositions on the layer of non-photosensitive polyimide or polyimide precursor compositions; (F) second prebaking the substrate; (G) forming patterns of the photoresist by exposing the substrate to masked radiaion and developing the photoresist; (H) etching the layer of said non-photosensitive polyimide or polyimide precursor compositions to form patterned polyimide or polyimide precursor compositions; (I) releasing or stripping the patterned layer of the photoresist compositions; and (J) baking the substrate with patterned non-photosensitive polyimide or polyimide precursor compositions to form the pixel-defining layer.