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.
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Harnessing sunlight to fuel the future through covalent organic frameworks
Solan, India (SPX) Aug 16, 2021
Be it rising fuel prices or failures in electricity power grids, the consequences of global energy crisis are hard to ignore. The need for alternate fuel sources is greater than ever, but, despite the popularity of solar panels, a vast amount of solar energy goes untapped. Now, a multinational team of researchers explore existing research on covalent organic frameworks (COFs), a new class of light-absorbing compounds, as a potential solution for efficient solar-driven fuel production.
Photocatalys … read more