3 research outputs found
Novel CdS Hole-Blocking Layer for Photostable Perovskite Solar Cells
Currently, the stability issue of
the perovskite solar cells (PSCs)
is one of the most critical obstacles in the commercialization of
PSCs. Although incredible advances in the photovoltaic efficiencies
of PSCs have been achieved in the past few years, research on the
stability of PSCs has been relatively less explored. In this study,
a new kind of CdS hole-blocking layer replacing the traditional compact
TiO<sub>2</sub> layer is developed to improve the photostability of
PSCs because the intrinsic oxygen vacancies of the TiO<sub>2</sub> surface are suspected to be the main cause for the photoinduced
degradation of PSCs. As a result, PSCs with the CdS layer exhibit
considerably improved photostability, maintaining over 90% of the
initial efficiency after continuous sunlight illumination for 12 h,
while the TiO<sub>2</sub> PSC retains only 18% of the initial efficiency
under the same conditions. Charge-transfer characteristics related
to photodegradation are investigated by various analyses including
electrochemical impedance spectroscopy and open-circuit voltage decay
and time-resolved photoluminescence decay measurements. the CdS PSC
exhibits negligible degradation in the charge-carrier dynamics, while
the TiO<sub>2</sub> PSC suffers from severely damaged characteristics
like increased charge recombination rate, charge-transfer resistance,
and reduced charge extraction rate
Core/Shell Structured TiO<sub>2</sub>/CdS Electrode to Enhance the Light Stability of Perovskite Solar Cells
In
this work, enhanced light stability of perovskite solar cell
(PSC) achieved by the introduction of a core/shell-structured CdS/TiO<sub>2</sub> electrode and the related mechanism are reported. By a simple
solution-based process (SILAR), a uniform CdS shell was coated onto
the surface of a TiO<sub>2</sub> layer, suppressing the activation
of intrinsic trap sites originating from the oxygen vacancies of the
TiO<sub>2</sub> layer. As a result, the proposed CdS-PSC exhibited
highly improved light stability, maintaining nearly 80% of the initial
efficiency after 12 h of full sunlight illumination. From the X-ray
diffraction analyses, it is suggested that the degradation of the
efficiency of PSC during illumination occurs regardless of the decomposition
of the perovskite absorber. Considering the light-soaking profiles
of the encapsulated cells and the OCVD characteristics, it is likely
that the CdS shell had efficiently suppressed the undesirable electron
kinetics, such as trapping at the surface defects of the TiO<sub>2</sub> and preventing the resultant charge losses by recombination. This
study suggests that further complementary research on various effective
methods for passivation of the TiO<sub>2</sub> layer would be highly
meaningful, leading to insight into the fabrication of PSCs stable
to UV-light for a long time
Enhancing Stability of Perovskite Solar Cells to Moisture by the Facile Hydrophobic Passivation
In this study, a novel and facile
passivation process for a perovskite solar cell is reported. Poor
stability in ambient atmosphere, which is the most critical demerit
of a perovskite solar cell, is overcome by a simple passivation process
using a hydrophobic polymer layer. Teflon, the hydrophobic polymer,
is deposited on the top of a perovskite solar cell by a spin-coating
method. With the hydrophobic passivation, the perovskite solar cell
shows negligible degradation after a 30 day storage in ambient atmosphere.
Suppressed degradation of the perovskite film is proved in various
ways: X-ray diffraction, light absorption spectrum, and quartz crystal
microbalance. This simple but effective passivation process suggests
new kind of approach to enhance stability of perovskite solar cells
to moisture