High efficiency and stability of perovskite solar cells using MD-697 doped poly (9-vinyl carbazole) modified interface of PCBM/perovskite layers

Using interface modification is an effective method to improve the crystallinity and stability of perovskite solar cells (PSCs). P-type poly(9-vinylcarbazole) (PVK) inserted the interface of perovskite and electron transport layer (ETL), which can improve the crystallinity and stability of PSCs. However, pure PVK-modified interface of perovskite/ETL is sensitive to the modified thickness and UV exposure, which can only improve limited PCE and anti-UV durability compared to the reference PSCs. The anti-oxidant (1,2-dioxoethylene)bis(iminoethylene) bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (MD-697) doped into poly (9-vinyl carbazole) (PVK) was firstly introduced to modify the interface of perovskite and phenyl-C 61 -butyric acid methyl (PCBM). MD-697:PVK-modified PSCs got the champion PCEs of 20.75% with less hysteresis effect, which is far higher than PCE (19.03%) of PVK-modified PSCs, (17.58%) MD-687-modified PSCs and (17.1%) of reference PSCs. MD-697:PVK-modified PSCs remained 89% of the original PCEs aged for 2800 h at room temperature and RH 85% under encapsulating condition and still remained 94% of the original PCE value aged for 6 h UV irradiation, which show best moisture resistance and UV durability. The joint coordination of C=O, NH and OH groups of MD-697 and carbazole groups of PVK can contribute to best crystallization of the perovskite layer, improving passivation effect and superior interface contact at perovskite/PCBM layers. The quasi-continuous two-dimension layer was formed on the surface of 3D perovskite film, which can further inhibit moisture invasion along grain boundaries. Therefore, MD-697:PVK jointly modified the perovskite film is an effective method to obtain efficient and stable PSCs.