Losses occur in all solar cells. One cause is the recombination of charge carriers at the interfaces. Intermediate layers at such interfaces can reduce these losses through so-called passivation. Self-assembled monolayers (SAMs) with a carbazole core are particularly well suited for the passivation of semiconductor surfaces made of perovskite materials. A team led by HZB physicist Prof. Steve Albrecht together with a group from Kaunas Technical University in Lithuania demonstrated this some time ago, developing a silicon-perovskite-based tandem solar cell with a record efficiency of over 29 % .
Now, for the first time, a team at HZB has analysed the charge carrier dynamics at the perovskite/SAM-modified ITO interface in more detail. From time-resolved surface photovoltage measurements, they were able to extract the density of "electron traps" at the interface as well as the hole transfer rates using a minimalist kinetic model. Complementary information was provided by measuring the time-resolved photoluminescence.
"We were able to determine differences in passivation quality, selectivity and hole transfer rates depending on the structure of the SAM, and demonstrate how the time-resolved surface photovoltage and photoluminescence techniques are complementary," explains Dr. Igal Levine, postdoc at HZB and first author of the paper. Time-resolved surface photovoltage proves to be a relatively simple technique for quantifying charge extraction at buried interfaces that could significantly facilitate the design of ideal charge-selective contacts.
Joule
Experimental study
Not applicable
Charge Transfer Rates and Electron Trapping at Buried Interfaces of Perovskite Solar Cells
17-Aug-2021
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