Renewable

January 25 (Renewables Now) - Replacing the electron-transport layers of perovskite solar cells with quantum dots increases their efficiency, operational stability and scalability, allowing for a power-conversion efficiency surpassing 20% in 64 sq cm cells.

This was announced Friday by scientists at the Swiss Federal Institute of Technology Lausanne (EPFL), the Korea Institute of Energy Research, Ulsan National Institute of Science and Technology, University of Ulsan, Zurich University of Applied Sciences and Uppsala University. They replaced the titanium dioxide electron-transport layer of perovskite cells with a thin layer of polyacrylic acid–stabilized tin (IV) oxide quantum dots to achieve better efficiency and also maintain good performance in large devices.

On a 0.08 sq cm cell, the efficiency achieved was a record 25.7%. For cells of 1, 20 and 64 sq cm it stood at 23.3%, 21.7% and 20.6%, respectively.

The team showed how quantum dots improve the solar cells’ light-capturing capacity, while also suppressing nonradiative recombination – a phenomenon reducing the efficiency of the device.

Quantum dots are nanometer-sized particles that act as semiconductors, and emit light when illuminated. They were studied by the scientists as an alternative to the electron-transport layer, made with mesoporous titanium dioxide, which exhibits low electron mobility. It is also “susceptible to adverse, photocatalytic events under ultraviolet light”.

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