4 research outputs found
Improvement in Solid-State Dye Sensitized Solar Cells by <i>p</i>‑Type Doping with Lewis Acid SnCl<sub>4</sub>
The
Lewis acid SnCl<sub>4</sub> is employed as a <i>p</i>-type
dopant for 2,2′,7,7′-tetrakisÂ(<i>N</i>,<i>N</i>-di-<i>p</i>-methoxyphenylamine)-9,9′-spirobifluorene
(spiro-OMeTAD) for the solution process in solid-state dye sensitized
solar cell. The UV–vis absorption spectra and time-resolved
photoluminescence (PL) spectra are used to investigate the doping
level of spiro-OMeTAD with a <i>p</i>-type dopant, indicating
the strong molecular acceptor of SnCl<sub>4</sub>. X-ray photoelectron
spectra (XPS) exhibiting close energy shifts of the Fermi level toward
HOMO are observed when adding Li salt or SnCl<sub>4</sub>. A significant
enhancement in fill factor of the photovoltaic devices, corresponding
to the power conversion efficiency, is observed when doping with SnCl<sub>4</sub>. This is attributed to the low charge transport resistance
of the hole transport film and high hole injection efficiency from
the hole transport material to the counter electrode
Hole-Conductor-Free Mesoscopic TiO<sub>2</sub>/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Heterojunction Solar Cells Based on Anatase Nanosheets and Carbon Counter Electrodes
A hole-conductor-free fully printable
mesoscopic TiO<sub>2</sub>/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> heterojunction solar
cell was developed with TiO<sub>2</sub> nanosheets containing high
levels of exposed (001) facets. The solar cell embodiment employed
a double layer of mesoporous TiO<sub>2</sub> and ZrO<sub>2</sub> as
a scaffold infiltrated by perovskite as a light harvester. No hole
conductor or Au reflector was employed. Instead, the back contact
was simply a printable carbon layer. The perovskite was infiltrated
from solution through the porous carbon layer. The high reactivity
of (001) facets in TiO<sub>2</sub> nanosheets improved the interfacial
properties between the perovskite and the electron collector. As a
result, photoelectric conversion efficiency of up to 10.64% was obtained
with the hole-conductor-free fully printable mesoscopic TiO<sub>2</sub>/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> heterojunction solar
cell. The advantages of fully printable technology and the use of
low-cost carbon-materials-based counter electrode and hole-conductor-free
structure provide this design a promising prospect to approach low-cost
photovoltaic devices
Boron-Doped Graphite for High Work Function Carbon Electrode in Printable Hole-Conductor-Free Mesoscopic Perovskite Solar Cells
Work function of
carbon electrodes is critical in obtaining high open-circuit voltage
as well as high device performance for carbon-based perovskite solar
cells. Herein, we propose a novel strategy to upshift work function
of carbon electrode by incorporating boron atom into graphite lattice
and employ it in printable hole-conductor-free mesoscopic perovskite
solar cells. The high-work-function boron-doped carbon electrode facilitates
hole extraction from perovskite as verified by photoluminescence.
Meanwhile, the carbon electrode is endowed with an improved conductivity
because of a higher graphitization carbon of boron-doped graphite.
These advantages of the boron-doped carbon electrode result in a low
charge transfer resistance at carbon/perovskite interface and an extended
carrier recombination lifetime. Together with the merit of both high
work function and conductivity, the power conversion efficiency of
hole-conductor-free mesoscopic perovskite solar cells is increased
from 12.4% for the pristine graphite electrode-based cells to 13.6%
for the boron-doped graphite electrode-based cells with an enhanced
open-circuit voltage and fill factor
The Influence of the Work Function of Hybrid Carbon Electrodes on Printable Mesoscopic Perovskite Solar Cells
In
printable mesoscopic perovskite solar cells (PSCs), carbon electrodes
play a significant role in charge extraction and transport, influencing
the overall device performance. The work function and electrical conductivity
of the carbon electrodes mainly affect the open-circuit voltage (<i>V</i><sub>OC</sub>) and series resistance (<i>R</i><sub>s</sub>) of the device. In this paper, we propose a hybrid carbon
electrode based on a high-temperature mesoporous carbon (m-C) layer
and a low-temperature highly conductive carbon (c-C) layer. The m-C
layer has a high work function and large surface area and is mainly
responsible for charge extraction. The c-C layer has a high conductivity
and is responsible for charge transport. The work function of the
m-C layer was tuned by adding different amounts of NiO, and at the
same time, the conductivities of the hybrid carbon electrodes were
maintained by the c-C layer. It was supposed that the increase of
the work function of the carbon electrode can enhance the <i>V</i><sub>OC</sub> of printable mesoscopic PSCs. Here, we found
the <i>V</i><sub>OC</sub> of the device based on hybrid
carbon electrodes can be enhanced remarkably when the insulating layer
has a relatively small thickness (500–1000 nm). An optimal
improvement in <i>V</i><sub>OC</sub> of up to 90 mV could
be achieved when the work function of the m-C was increased from 4.94
to 5.04 eV. When the thickness of the insulating layer was increased
to ∼3000 nm, the variation of <i>V</i><sub>OC</sub> as the work function of m-C increased became less distinct