Electrochemical impedance spectroscopy technique for 2D/3D n-i-p structured perovskite solar cells
Zubair Ahmad a b, Ehsan Raza a b
a Qatar University Young Scientists Center (QUYSC), Qatar University, 2713, Doha, Qatar
b Centre for Advanced Materials (CAM), Qatar University, 2713, Doha, Qatar
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Oral, Ehsan Raza, presentation 164
DOI: https://doi.org/10.29363/nanoge.hopv.2022.164
Publication date: 20th April 2022

The 2D/3D perovskite solar cells (PSCs) have shown great potential to replace conventional silicon solar cells, with their efficiencies exceeding 20%. Moreover, the 2D capping layer extensively enhanced the stability of PSCs due to the presence of hydrophobic organic cations in the 2D material that block any moisture intrusion. However, even in the presence of a 2D capping layer, these PSCs have still shown slow degradation over a prolonged period of time. Therefore, there is a requirement to understand the complex dynamic processes that take place in these PSCs to develop new stability and performance enhancement strategies. The electrochemical impedance spectroscopy (EIS) analysis technique has shown remarkable potential in the field of PSCs, owing to its capability of separating resistive and capacitive behaviors. The simultaneously occurring complex processes at the PSC’s interfaces can be analyzed independently with this cutting-edge technique. We have successfully applied this technique on n-i-p structured 2D/3D PSCs to comprehensively analyze their interfacial processes. In the 2D/3D PSC study, a degradation analysis over a period of 5000 h with an interval of 2500 h was performed using EIS, narrowing the study to Au/HTM/perovskite interface aging, as the degradation processes in this region are undoubtedly complex to analyze. The charge transfer resistance (Rct) at the Au/HTM/perovskite interface in 2D/3D PSCs was observed to be decreasing with aging. This decrease was attributed to the penetration of Au in the HTM layer, increasing the electric contact area. It was deduced that morphological changes in the PSCs were the causes of charge accumulation and changes in Rct. At the same aging time, the 2D/3D PSCs showed much slower degradation as compared to 3D PSCs indicated by a smaller Rct, as the 2D capping layer minimizes the degradation of perovskite by forming a protective layer against external environmental factors. Our findings will be helpful for comprehensively understanding the charge dynamics and degradation processes in PSCs. A unique approach was utilized to describe the degradation behavior in the Au/HTM/perovskite interface of 2D/3D PSCs. These findings will help deepen our understanding of PSCs and pave our way to developing effective stability enhancement criteria.

This work was made possible by NPRP grant # NPRP11S-1210–170080 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. 

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