  The Perovskite absorber layer, the electron transport layer (ETL), the hole
transport layer (HTL), and the transparent conducting oxide layer (TCO) are the
major components that make up a Perovskite solar cell. Between ETL and HTL, the
absorber layer is sandwiched, on which electron-hole pairs are created after
absorption of solar radiation. Despite substantial progress toward efficiency,
long-term stability still remains a serious concern. Present work focuses
toward contributing on the later issue by adopting Titanium dioxide (TiO2) as
ETL and reduced graphene oxide (rGO) as HTL. Specifically, in the present work,
we report our efforts on the preparation of compact titanium dioxide (C-TiO2)
and mesoporous titanium dioxide (M-TiO2) layers as an ETL and a reduced
graphene oxide thin film as a HTL. The C-TiO2 film was spin casted on FTO glass
followed by casting of M-TiO2 film using Doctor Blading technique. Similarly,
the rGO film was produced by spray casting over the glass substrate. The
as-prepared ETL and HTL layers were characterized by measuring their optical
properties (transmittance and reflectance of thin films). Then, the bandgap, Eg
was extracted from reflectance and transmittance curves for ETL and HTL
respectively. In the case of rGO, we found the value of Eg to be 2.1 eV, which
varies between 2.7eV and 0.02eV depending upon its reduction level based on the
previously reported values. Similarly, the bandgap of the C-TiO2 was 4.51 eV
which was reduced to 4.12 eV after the addition of M-TiO2, which are 0.9 to 1.1
eV higher than previously reported values. However, bandgap shows decreasing
trend after employing M- TiO2 over C-TiO2. In a Perovskite solar cell, both ETL
and HTL will be investigated.
