posted on 2024-02-15, 13:03authored byXiangtian Chen, Hannu P. Pasanen, Ramsha Khan, Nikolai V. Tkachenko, Csaba Janáky, Gergely Ferenc Samu
The kinetics of electron extraction at the electron transfer
layer/perovskite
interface strongly affects the efficiency of a perovskite solar cell.
By combining transient absorption and time-resolved photoluminescence
spectroscopy, the electron extraction process between FA0.83Cs0.17Pb(I0.83Br0.17)3 and TiO2 single crystals with different orientations
of (100), (110), and (111) were probed from subpicosecond to several
hundred nanoseconds. It was revealed that the band alignment between
the constituents influenced the relative electron extraction process.
TiO2(100) showed the fastest overall and hot electron transfer,
owing to the largest conduction band and Fermi level offset compared
to FA0.83Cs0.17Pb(I0.83Br0.17)3. It was found that an early electron accumulation in
these systems can have an influence on the following electron extraction
on the several nanosecond time scale. Furthermore, the existence of
a potential barrier at the TiO2/perovskite interface was
also revealed by performing excitation fluence-dependent measurements.