Zernike seminar: Prof. Ahmad Kermanpur - Improved electron transport in planar perovskite solar cells using ultra-thin bilayer structures

The minimization of interfacial losses through interface engineering is crucial to achieve
efficient, stable and hysteresis-free planar perovskite solar cells (PSCs). The
recombination and extraction of electron–hole pairs at the electron transport layer
(ETL)/perovskite interface significantly impact the power conversion efficiency of PSCs.
In this seminar, the role of inserting an ultra-thin layer (UTL) of a metal oxide (<10 nm
thick) in the cell structure on the photovoltaic performance of a planar PSC is discussed.
For this purpose, all types of single layer and bilayer structured ETLs of TiO 2 , SnO 2 , and WO 3 , i.e.,
three common metal oxide electron transport materials in PSCs, were provided using the reproducible
and industry-compatible radio-frequency sputtering method. It was found that a significant increase in
cell efficiency can be obtained using the bilayer structures of TiO 2 /WO 3 -UTL, SnO 2 /WO 3 -UTL
and TiO 2 /SnO 2 -UTL as a result of more efficient energy band alignment. Conversely, reduced
efficiency is observed by using their inverted structures, namely WO 3 /TiO 2 -UTL, WO 3 /SnO 2 -UTL
and SnO 2 /TiO 2 -UTL. These results suggest a simple and promising strategy to enhance the efficiency of photovoltaic devices.