Interface passivation of perovskite solar cells with novel cations

2022-8
Çel, Gülsevim Bensu
Interface engineering and surface defect passivation play an important role in the development of state-of-the-art perovskite solar cells. Forming an additional two-dimensional (2D) layer on top of the primary perovskite absorber after treatment with organic spacers not only passivates defects and improves the device performance, but also enhances stability. In this study, two novel cations, that are 2,6-methoxy-phenylethyl ammonium iodide (2,6-MeO-PEAI) and 3,5-methoxy-phenylethyl ammonium iodide (3,5-MeO-PEAI) were used on top of (FAPbI3)1−x(MAPbBr3)x (FAMA) perovskite, which resulted in an increase in open- circuit voltage (VOC) and enhancement of stability. Additionally, the effect of annealing after cation treatment was investigated in detail. Grazing incidence X-ray diffraction measurements revealed that 2,6-MeO-PEAI salt did not form pure 2D perovskite, whereas 3,5-MeO-PEAI salt created a 2D layer upon annealing. Both photoluminescence and impedance spectroscopy measurements indicated that nonradiative recombination was reduced upon salt treatment, which led to an increase in VOC. A VOC value as high as 1.14 eV was achieved with the addition of 3,5-MeO-PEAI salt, however, cells with 2,6-MeO-PEAI salt exhibited the best overall performance, exceeding the efficiency of reference cells. The power conversion efficiency (PCE) increased from 18.14% for the reference cell to 19.15% for the cell treated with 2,6-MeO-PEAI. Moreover, moisture resistance of the salt-treated devices enhanced greatly, which was proved with contact angle measurements. After six weeks from the fabrication, the reference cell, and the cells treated with 2,6-MeO-PEAI and 3,5-MeO-PEAI maintained 77%, 93% and 94% of the initial PCE, respectively, which clearly demonstrated the long-term stability enhancement upon salt treatment.

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Citation Formats
G. B. Çel, “Interface passivation of perovskite solar cells with novel cations,” M.S. - Master of Science, Middle East Technical University, 2022.