摘要
Although the photovoltaic efficiency of organic solar cells(OSCs)has exceeded 17%,poor lifetime excludes OSCs from practical use.In particular,UV rays in sunlight may cause the decomposition of organic photovoltaic materials,which has been proved to be the main reason for the efficiency decay.At present,there is still no effective approach to substantially improve the device stability.Herein,we fabricate a highly efficient OSC with exceptional stability under sunlight illumination by incorporating a UV-resistant cathode interlayer(CIL),namely(sulfobetaine-N,Ndimethylamino)propyl naphthalene diimide(NDI-B).NDI-B was designed and synthesized based on the naphthalene diimide(NDI)unit,thereby exhibiting excellent capability of electron collection.Moreover,NDI-B shows strong absorption in the UV region and has good UV resistance.Devices using NDI-B as a CIL exhibited a photovoltaic efficiency of 17.2%,representing the state-of-the-art photovoltaic performance of OSCs.Notably,the NDI-B-modified OSC exhibited a T80 of over 1800 h under full-sun AM 1.5 G illumination(100 mW cm^(−2)),which represents the best stability for OSCs.We demonstrate that the unique ability of the NDI-B interlayer to convert UV light to an additional photocurrent can effectively protect photovoltaic materials from UV-induced decomposition,which is the key to obtain high OSC stability under operational conditions.
基金
The authors acknowledge the financial support from the National Key Research and Development Program of China(no.2019YFA0705900)funded by MOST
the Youth Innovation Promotion Association CAS(no.2018037)
the National Natural Science Foundation of China(no.21875263)
the Basic and Applied Basic Research Major Program of Guangdong Province(no.2019B030302007).
