1. School of Energy and Power Engineering，North University of China，Taiyuan 030051，China
2. Key Laboratory of Interface Science and Engineering in Advanced Materials，Ministry of Education，
Taiyuan University of Technology，Taiyuan 030024，China
3. Printed Electronics Research Center，Suzhou Institute of Nano-Tech and Nano-Bionics，Chinese Academy of Sciences (CAS)，Suzhou 215123，China
4. College of Materials Science and Engineering，Taiyuan University of Technology，Taiyuan 030024，China
In order to improve the lifetime of organic photovoltaic devices, encapsulation technology is often used to limit the exposure of solar cells to water and oxygen. Despite a series of advances in the encapsulation field of organic solar cells (OSCs), the damage caused by the encapsulation process has rarely been studied in the literature. In this paper, inverted OSCs with high stability were prepared by using classical poly(3-hexylthiophene) as the donor, [6,6]phenyl-C61-butyric acid methyl ester as the acceptor, piperazine that can improve stability of device as the third component, zinc oxide (ZnO) and molybdenum trioxide (MoO3) as the transport layer material. The effect of ultraviolet (UV) curing adhesive commonly used in large-scale roll-to-roll device encapsulating on the photoelectric conversion efficiency and stability is systematically investigated. The results are as follows: the performance (such as open-circuit voltage, short-circuit current density, fill factor, and power conversion efficiency) of UV glue-encapsulated devices shows a continuous decline with the prolongation of the irradiation time. Meanwhile, the performance of the aging devices is restored after replacing the MoO3/Al electrode, which confirms that the MoO3/Al interface corruption is an important reason for the performance attenuation of the device. Laser beam induced current imaging shows a center-to-edge failure process in UV glue-encapsulated device. Based on this, the following degradation mechanism is proposed: the photoinitiator in the UV glue will generate a strong protonic acid under UV light irradiation, and react with MoO3, which hinders the effective transmission of the hole, and ultimately reduces the device efficiency significantly. In addition, an effective ethylene-vinyl acetate copolymer encapsulation process for OSCs devices has also been developed. This study provides a new understanding of the UV glue encapsulation process, and also develops a new strategy for improving the stability of organic solar c