[19a-C103-1~12] 6.4 Thin films and New materials

▲ [19a-C103-1] UV-assisted sol-gel processing of zinc oxide thin films for OLED encapsulation

〇Lina Sun¹, Yuu Kurosawa¹, Yoshiyuki Suzuri¹, Naoko Okimoto², Hiroki Maeda² (1.Yamagata Univ. INOEL, 2.Dai Nippon Printing)

Keywords:zinc oxide thin films, sol-gel process, thin-film encapsulation (TFE)

In an effort to realize flexible electronics with low cost, all solution processed roll to roll (R2R) production and long-term stability, the thin-film encapsulation (TFE) imposes the highest challenge, because a very high level of barrier performance needs to be achieved without relying on a high temperature process. To achieve this goal, we have recently established a UV-assisted sol-gel method to obtain highly transparent, smooth and dense ZnO thin films at room temperature which is promising as a TFE. Spin-coating of a precursor solution containing zinc acetate (Zn(OAc)2) under N2 (in a glove box) was followed by vacuum ultraviolet (VUV) irradiation, resulting in a photochemical cleavage of the ligands to promote condensation by forming Zn-O-Zn bonds to form a compact amorphous ZnO. The performance of the ZnO thin films as thin-film encapsulation (TFE) layer of an OLED device has also been investigated. The lifetime of the device was extended by about 4 times to prove the effectiveness of thus prepared ZnO as a TFE to block humidity and oxygen, despite of the rather small thickness (60 nm).