Solar cells generally gives slightly high efficiency in reverse scan than that of forward scan? What is the reason behind it?
Dear Hasan,
welcome
The cause of the hysteresis is the presence of positive mobile ions. Under shortcircuit conditions the positive ions will be displaced at the maximum distance from their neutralizing negative ions because of the built in electric field.
In the forward scan the ions will be displaced from their initial position nearer to their negative ions causing a displacement current in the opposite of the photocurrent and therefore decrease it from its value if the charges are absent. When reversing the scanning the positive ions reverse their journey away from the negative ions causing a current aiding the photocurrent and therefore the current increases more than the current in the forward direction.
So, this explains why the current in the forward scan is smaller in the reverse scan at the same scan voltage.
Best wishes
Dear Hasan,
welcome
The cause of the hysteresis is the presence of positive mobile ions. Under shortcircuit conditions the positive ions will be displaced at the maximum distance from their neutralizing negative ions because of the built in electric field.
In the forward scan the ions will be displaced from their initial position nearer to their negative ions causing a displacement current in the opposite of the photocurrent and therefore decrease it from its value if the charges are absent. When reversing the scanning the positive ions reverse their journey away from the negative ions causing a current aiding the photocurrent and therefore the current increases more than the current in the forward direction.
So, this explains why the current in the forward scan is smaller in the reverse scan at the same scan voltage.
Best wishes
Research interest has been paid
to the development of perovskite solar cells, which
has experienced a steep increase in efficiency from 9.7%
in 2012 to 22.1% in 2016 , thus proving to be a
competent rival to established photovoltaic technologies based
on Si, GaAs, CdTe, etc. . In 2009, organic–inorganic halide
perovskite (CH3NH3PbI3) was used as a photosensitizer in
dye-sensitized solar cells by Kojima et al. [4] achieving an
efficiency of 3.8%. By 2012, research on CH3NH3PbI3, as a
solar absorber, had significantly increased and an
efficiency of more than 21% has been reported in the literature
recently 22.1% .other experimental works pertaining solution processed
and vapor deposited perovskite solar cells as
well as exploring the role of transport layers have been
reported.
Among the theoretical works, there are mainly numerical
analyses in the literature with only few analytical
works having been reported for perovskite solar cells.
Taretto et al.presented an analytical drift-diffusion model
for p-i-n perovskite solar cells, where they simplified the
photo-generation rate, approximating it as a “priori” (deductive
parameter) by analyzing the J–V curves before fitting. The
generation rate, therefore, is calculated from the short-circuit
current density of a known experimental model, confining
their model to the study of only known data. According to
standard transfer matrix formalism (TMF), the generation rate
shows a fluctuating profile in thin absorbers due to the position
dependence. .
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