High fill factor over 82% enabled by a biguanide doping electron transporting layer in planar perovskite solar cells

Abstract

N-type doping in electron transport materials is an effective way to improve the electron collection and enhance the performance of the perovskite solar cells (PSCs). Here, for the first time, an antibiotic and antimicrobial compound of 1-(o-Tolyl) biguanide (oTb) is used to dope the electron transport material of phenyl-C₆₁-butyric acid methyl ester (PCBM). The oTb doping into the PCBM can increase the conductivity and reduce the work function of the PCBM. The oTb doping can significantly enhance the fill factor (FF) of the perovskite solar cells with the structure of glass/ITO/NiO_x/MAPbI₃/(oTb)PCBM/(PEIE)/Ag. For the cells without PEIE (polyethylenimine ethoxylated) coating, the oTb doping increases the FF from 0.57 to 0.73. S-shaped of the current density-voltage (J-V) characteristic under illumination is removed after the oTb doping. For the cells with PEIE coating between the (oTb)PCBM and Ag, the oTb doping increases the FF from 0.70 to 0.82. These results show the potential of the oTb as an n-dopant in the applications of perovskite solar cells.

Keywords

perovskite solar cells / n-doping / biguanide / fill factor (FF) / electron transporting layer

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Acknowledgements

The work was supported by the National Natural Science Foundation of China (Grant Nos. 21474035 and 51773072), the Recruitment Program of Global Youth Experts, the Huazhong University of Science and Technology (HUST) Innovation Research Fund (Nos. 2016JCTD111 and 2017KFKJXX012), the Science and Technology Program of Hubei Province (No. 2017AHB040) and China Postdoctoral Science Foundation funded project (No. 2016M602289).

Author contributions

R. G., F. Q. and Y. H. Z. conceived the idea. R. G. and F. Q. performed the solar cell fabrication, optimization and measurement. R. G., F. Q. and S. X. X. performed the film conductivity measurement. Y. H. Z. directed this work. R. G. wrote the first draft of the manuscript. All the authors revised and approved the manuscript.

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2018 Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature