Side-Chain Polyimides as Binder Polymers for Photolithographic Patterning of a Black Pixel Define Layer for Organic Light Emitting Diode

Abstract

A pixel define layer (PDL) in an organic light emitting diode (OLED) is patterned using a photolithographic process before the deposition of organic layers on top of ITO anode. If the patterning of PDL on OLED panels can be achieved using a black photoresist, the patterning of black matrix (BM) on top of PDL patterns can be omitted by reducing the reflection of ambient light from OLED panels. In this study, we synthesized a series of side-chain-type polyimides as binder polymers of black photoresists and investigated the potential of using the black photoresist for the fine patterning of black PDL on OLED panels.

Acidic Polyester Imides as Thermally Stable Binder Polymers for Negative-Tone Black Photoresist

“…The use of negative-tone black photoresist instead of positive-tone photosensitive polyimide photoresist can simplify the OLED panel fabrication process by omitting the 1/4λ polarizing film and BM patterning. A typical negative-tone black photoresist includes photoinitiator, multifunctional monomers, black pigment millbase and binder polymer, which can be developed with aqueous alkaline solution in the photolithographic process [2]. The role of binder polymer is crucial in the patterning of black PDL on the OLED panel.…”

Synthesis of New Binder Polymers for Photolithographic Patterning of Black Pixel Define Layers of Organic Light Emitting Diode

“…The photoresist based on positive-tone photosensitive polyimide has been used to fabricate the pixel define layer (PDL) of OLED panel for the small-size OLED devices, which is able to exhibit good resolution and high contrast [9]. In order to further improve the visibility of OLEDs, the black photoresist based on negative-tone photosensitive system has been studied actively [10] [11]. A typical negative-tone black photoresist consisted of photoinitiator, photosensitizer, binder polymer, multifunctional monomer and black mill base, which makes the color of patterned PDL black to reduce the reflection of ambient light from the OLED panel.…”