posted on 2020-08-04, 13:36authored byKonstantina Gkini, Nikolaos Balis, Michael Papadakis, Apostolis Verykios, Maria-Christina Skoulikidou, Charalampos Drivas, Stella Kennou, Matthias Golomb, Aron Walsh, Athanassios G. Coutsolelos, Maria Vasilopoulou, Polycarpos Falaras
An
interfacial engineering approach was adopted in order to optimize
the photovoltaic parameters and the stability of n-i-p planar perovskite
solar cells (PSCs). A thin manganese (Mn) porphyrin [(TMePyP)I4Mn(AcO)] layer was introduced between the titania (TiO2) electron transport layer (ETL) and the perovskite absorber.
The introduction of porphyrin onto the TiO2 substrate provoked
a significant decrease in the work function (WF), which arose from the large local dipole moment. The modification
also provided a more hydrophobic environment that favored the growth
of homogeneous and large perovskite crystals. Moreover, the electron
charge transport to the ETL was facilitated via the highly paramagnetic
character of the Mn porphyrin, whereas the negative impact of humidity
and oxygen on the PSC performance was hindered. Density functional
theory analysis justified the observed large decrease of the WF and the strong electronic coupling of porphyrin
with the TiO2 compact layer (following the porphyrin deposition),
which are beneficial for electron extraction. By combining the Mn
porphyrin and the CH3NH3PbI3 perovskite,
significant enhancement of the stabilized power conversion efficiency
by 22% was recorded. The shelf-shield stability was also improved
after more than 600 h of storage in the dark under ambient conditions.