Increase of halide perovskite stability with piperidine derivatives in 2D/3D structures
Vsevolod Mazov a, Pavel Gostishchev a, Saranin Danila a, Denis Kuznetsov b, Aldo Di Carlo c
a LASE–Laboratory for Advanced Solar Energy, National University of Science and Technology MISiS, Leninsky Avenue, 6, Moskva, Russian Federation
b Department of Functional Nanosystems and Hightemperature Meterials, NUST MISiS, Leninsky Avenue, Moskva, Russian Federation
c University of Rome “Tor Vergata”, Rome, Postal Code, Italy.
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Poster, Vsevolod Mazov, 103
Publication date: 11th February 2019

Despite the large efficiency, easy fabrication route and low cost, [1] the poor stability of perovskite solar cells (PSCs) does not allow them to be competitive with respect to commercial photovoltaic technologies. PSCs are exposed to degradation under the action of oxygen and solar radiation due to the superoxide radical formation, which leads to the destruction of the structure of CH3NH3PbI3 to molecular iodine, lead iodide and methylamine [2]. That could be prevented by adding nitroxide compounds, such as 4-amino-2,2,6,6-tetra methylpiperidin-1-yl (oxyl) (TEMPO) [3], [4], inside the structure of perovskiteAlso, in recent years many researches are focused on increasing the stability and efficiency of solar cells by creating 2D/3D perovskite structures [5]. In the conventional approach, the structure formation of 2D-perovskite is achieved by applying an intercalating ligand, that is not able to penetrate into the perovskite lattice, after the formation of the planar 3D film. The traditional substances in this case are diamine derivatives such as diamino-butane, as well as arene derivatives such as benzylmethylammine and their salts [6], [7].In our work, these two approaches were combined to synthesize 2D/3D structures with nitroxide radicals. To this end, TEMPO and its synthetic precursor 4-amino-2,2,6,6-tetramethylpiperidine with concentrations from 0.1 to 0.001 % by volume in iso-propanol was applied onto the freshly prepared perovskite layer in ambient conditions.It was found that the treated samples have significantly higher fluorescence relative to the reference samples (increment ranged from 12% to 33%) with a slight decrease in light absorption. Both these factors suggest that the resulting photocurrent should also increase, as it was shown in studies of devices with the modified perovskite. After that, the accelerated degradation of these films under the action of intense light irradiation, approximately 200 000 lx, was studied through the light absorption measurements. It was shown that the treated samples lifetime increases almost twice, relative to the untreated ones. XRD data prove that this improved lifetime can only be explained due to the intercalation of piperidine derivatives in 3D film with the formation of separate 2D layers and not as a result of the surface passivation the of perovskite grains. The occurrence of characteristic shifted XRD peaks show the formation of a 2D/3D structure.Based on these results, new type of 2D/3D perovskite structures with increased stability were synthesized. It was shown that small amount of piperidine deverbatives could rise PCE and also prevent photodegradation.

The authors gratefully acknowledge the financial support of the Ministry of Education and Science of the Russian Federation in the framework of Megagrant No. 14.Y26.31.0027.

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