Scientists in Belgium have investigated how perovskietabsorbers used in solar cells under three different stress test types and have shown that the interface between the perovskiet layer and the electron transport layer suffers from weak thermal adheric stability, which creates the conditions for performance losses.
Researchers from IMEC, Hasselt University and Ghent University in Belgium have investigated the impact of light and warmth on the degradation of Wide-Bandgap Perovskiet solar cells and have discovered that the cargo transport layers of the devices are the most important source of performance losses.
Their analysis was aimed at perovskiet materials with an energy band gap of 1.68 EV and the comparison of their performance with perovskites with an energy band gap of 1.61 EV.
“Wide band gap perovskites are usually confronted with poor stability under light and at raised temperatures,” they explained. “This is due to the phasegregation mechanism, in which bromide and iodides that are part of the perovskiet crystal separate into different phases, causing the stability of the layer to be hampered.”
For their assessment, the scientists used three standardized accelerated stress tests derived from the international top at organic photovoltaic stability (ISOs) protocols known as ISOS-L1 (long-term exposure to light), ISOS-D2 (thermal tension in the dark) and ISOS-L2 (thermal stress below light).
They also used an electric characterization toolbox that combined electricity tension (IV), photoluminescence (PL) and capacity frequent (CF) analysis. The solar cells were exposed to 1 sunlight intensity and an increased temperature of 60 C.
The tests showed that the main source of demolition in all analyzed perovskiet solar cells is the interface between the perovskietabsorberage and the electron transport material (ETL), due to “weak” thermal mechanical stability. In particular, the researchers discovered that the dielectric permittivity of the perovskiet was affected by the degradation caused by the combined effect of heat and light.
“This analysis showed that different breakdown modes are being observed in different stress conditions, and emphasize that ‘perovskiet stability’ may not be an absolute concept,” the researchers emphasized. “This important finding emphasizes the role of heat on the phasegregation process and on the demolition of broad band gap perovskites under operational conditions, which was overlooked in many earlier studies.”
Their findings can be found in the study “In -depth study of demolition in scalable wide bandgap perovskiet cells“Published in Materials Futures. Looking ahead, the team said that it wants to investigate the demolition at nano scale level in different stress conditions and perform more tests in a wider range of stress conditions, “possibly lead to the discovery of new breakdown modes.”
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