19 research outputs found
Impacts of Heterogeneous TiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> Composite Mesoporous Scaffold on Formamidinium Lead Trihalide Perovskite Solar Cells
Heterogeneous TiO<sub>2</sub> and
Al<sub>2</sub>O<sub>3</sub> composites were employed as a mesoporous
scaffold in formamidinium lead trihalide (FAPbI<sub>3–<i>x</i></sub>Cl<sub><i>x</i></sub>)-based perovskite
solar cells to modify surface properties of a mesoporous layer. It
was found that the quality and morphology of the perovskite film were
strongly affected by the TiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratio in the mesoporous film. The conversion efficiency of the perovskite
solar cell was improved by using a composite of TiO<sub>2</sub> and
Al<sub>2</sub>O<sub>3</sub> in comparison with TiO<sub>2</sub>- and
Al<sub>2</sub>O<sub>3</sub>-based cells, yielding 11.0% for a cell
with a 7:3 TiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> composite.
Our investigation shows a change of electron transport path depending
on a composition ratio of insulating Al<sub>2</sub>O<sub>3</sub> to
n-type semiconducting TiO<sub>2</sub> in a mesoporous layer
Enhanced Carrier Transport Distance in Colloidal PbS Quantum-Dot-Based Solar Cells Using ZnO Nanowires
Nanostructured solar cells are a promising area of research for the production
of low cost devices that may eventually be capable of complementing or even replacing
present technologies in the field of solar power generation. The use of quantum dots (QDs) in
solar cells has evolved from being simple absorbers in dye-sensitized solar cells to sustaining
the double functions of absorbers and carrier transporters in full solid state devices. In this
work, we use both optical and electrical measurements to explore the diffusion limitations of
carrier transport in cells made of a heterostructure combining lead sulfide (PbS) QDs as
absorbers and hole carrier and zinc oxide nanowires as electron carrier material. The results
show efficient charge collection along the PbS-QD/ZnO nanowire (NW) hybrid structure.
This is because of the formation of band bending in the ZnO collector, allowing efficient
charge separation and spatially well-separated carrier pathways, yielding a hole transportation
of over 1 μm. We have also found a limitation in open-circuit voltage (Voc) associated with
band bending in the ZnO collector.This research is supported by the Japan Science and Technology
Agency (JST) thorough its “Funding Program for Core Research
for Evolutional Science and Technology (339-5 CREST)”
and New Energy and Industrial Technology Development Organization (0520002 NEDO) and the Ministry of Economy,
Trade and Industry (METI), Japan. The work is also supported
by Generalitat Valenciana (ISIC/2012/008 Institute of Nanotechnologies
for Clean Energies, PROMETEO/2014/020). This
work is partly supported by JX Nippon Oil & Energy
Corporation. Cordial thanks are due to Toyo Corporation
for the use of the ModuLab system (Solartron) for obtaining
IMPS data
Amorphous Metal Oxide Blocking Layers for Highly Efficient Low-Temperature Brookite TiO<sub>2</sub>‑Based Perovskite Solar Cells
A fully low-temperature-processed
perovskite solar cell was fabricated with an ultrathin amorphous TiO<sub><i>x</i></sub> hole-blocking layer in combination with
brookite TiO<sub>2</sub> prepared at temperature <150 °C.
Structured with TiO<sub><i>x</i></sub>/brookite TiO<sub>2</sub> bilayer electron collector, the perovskite solar cells exhibit
high efficiency up to 21.6% being supported by high open-circuit voltage
and fill factor up to 1.18 V and 0.83, respectively. Compared to SnO<sub><i>x</i></sub> hole-blocking layer, TiO<sub><i>x</i></sub> has better electron band alignment with brookite TiO<sub>2</sub> and hence, results in higher efficiency
Temperature Effects on the Photovoltaic Performance of Planar Structure Perovskite Solar Cells
[EN] Temperature effects of CH3NH3PbI3 perovskite solar cells having simple planar architecture were investigated on the crystal structure and photovoltaic performance. The obvious changes in the CH3NH3PbI3 crystal structure were found by varying the temperature as a consequence to the augmentation in lattice parameters and expansion of the unit cell. The expansion of the crystal gave a serious influence on the performance of the solar cells, where the differences in the coefficients of the thermal expansion (CTEs) together with the lattice mismatch between TiO2 and perovskite materials might cause interfacial
defects responsible for the deterioration in the photovoltaic performance. Interestingly, the hysteresis in the cubic phase is very small because of the less distorted angles of the CH3NH3PbI3 structure against the temperature fluctuation.The present work has been supported by New Energy and Industrial Technology Development Organization (NEDO, Japan) and Japan Society for the Promotion of Science (JSPS) for Overseas Researchers. The authors acknowledge Ajay Kumar Jena for his help.Cojocaru, L.; Uchida, S.; Sanehira, Y.; González-Pedro, V.; Bisquert, J.; Nakazald, J.; Kubo, T.... (2015). Temperature Effects on the Photovoltaic Performance of Planar Structure Perovskite Solar Cells. Chemistry Letters. 44(11):1557-1559. https://doi.org/10.1246/cl.150781S15571559441
The Interface between FTO and the TiO<sub>2</sub> Compact Layer Can Be One of the Origins to Hysteresis in Planar Heterojunction Perovskite Solar Cells
Organometal halide perovskite solar
cells have shown rapid rise in power conversion efficiency, and therefore,
they have gained enormous attention in the past few years. However,
hysteretic photovoltaic characteristics, found in these solid-state
devices, have been a major problem. Although it is being proposed
that the ferroelectric property of perovskite causes hysteresis in
the device, we observed hysteresis in a device made of nonferroelectric
PbI<sub>2</sub> as a light absorber. This result evidently supports
the fact that ferroelectric property cannot be the sole reason for
hysteresis. The present study investigates the roles of some key interfaces
in a planar heterojunction perovskite (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3–<i>x</i></sub>Cl<sub><i>x</i></sub>) solar cell that can potentially cause hysteresis. The results
confirm that the interface between fluorine doped tin oxide (FTO)
substrate and the TiO<sub>2</sub> compact layer has a definite contribution
to hysteresis. Although this interface is one of the origins to hysteresis,
we think that other interfaces, especially the interface of the TiO<sub>2</sub> compact layer with perovskite, can also play major roles.
Nevertheless, the results indicate that hysteresis in such devices
can be reduced/eliminated by changing the interlayer between FTO and
perovskite
Controlled Crystal Grain Growth in Mixed Cation–Halide Perovskite by Evaporated Solvent Vapor Recycling Method for High Efficiency Solar Cells
We
developed a new and simple solvent vapor-assisted thermal annealing
(VA) procedure which can reduce grain boundaries in a perovskite film
for fabricating highly efficient perovskite solar cells (PSCs). By
recycling of solvent molecules evaporated from an as-prepared perovskite
film as a VA vapor source, named the pot-roast VA (PR-VA) method,
finely controlled and reproducible device fabrication was achieved
for formamidinium (FA) and methylammonium (MA) mixed cation–halide
perovskite (FAPbI<sub>3</sub>)<sub>0.85</sub>(MAPbBr<sub>3</sub>)<sub>0.15</sub>. The mixed perovskite was crystallized on a low-temperature
prepared brookite TiO<sub>2</sub> mesoporous scaffold. When exposed
to very dilute solvent vapor, small grains in the perovskite film
gradually unified into large grains, resulting in grain boundaries
which were highly reduced and improvement of photovoltaic performance
in PSC. PR-VA-treated large grain perovskite absorbers exhibited stable
photocurrent–voltage performance with high fill factor and
suppressed hysteresis, achieving the best conversion efficiency of
18.5% for a 5 × 5 mm<sup>2</sup> device and 15.2% for a 1.0 ×
1.0 cm<sup>2</sup> device
A Switchable High-Sensitivity Photodetecting and Photovoltaic Device with Perovskite Absorber
Amplified
photocurrent gain has been obtained by photodiodes of
inorganic semiconductors such as GaAs and Si. The avalanche photodiode,
developed for high-sensitivity photodetectors, requires an expensive
vapor-phase epitaxy manufacture process and high driving voltage (50–150
V). Here, we show that a low-cost solution-processed device using
a planar-structured ferroelectric organo-lead triiodide perovskite
enables light detection in a large dynamic range of incident power
(10<sup>–7</sup>–10<sup>–1</sup> W cm<sup>–2</sup>) by switching with small voltage (−0.9 to +0.5 V). The device
achieves significantly high external quantum conversion efficiency
(EQE) up to 2.4 × 10<sup>5</sup>% (gain value of 2400) under
weak monochromatic light. On a single dual-functional device, incident
small power (0.2–100 μW cm<sup>–2</sup>) and medium
to large power (>0.1 mW cm<sup>–2</sup>) are captured by
reverse
bias and forward bias modes, respectively, with linear responsivity
of current. For weak light detection, the device works with a high
responsivity value up to 620 A W<sup>–1</sup>
Lead-free perovskite solar cells using Sb and Bi-based A3B2X9 and A3BX6 crystals with normal and inverse cell structures
Abstract Research of CH3NH3PbI3 perovskite solar cells had significant attention as the candidate of new future energy. Due to the toxicity, however, lead (Pb) free photon harvesting layer should be discovered to replace the present CH3NH3PbI3 perovskite. In place of lead, we have tried antimony (Sb) and bismuth (Bi) with organic and metal monovalent cations (CH3NH3 +, Ag+ and Cu+). Therefore, in this work, lead-free photo-absorber layers of (CH3NH3)3Bi2I9, (CH3NH3)3Sb2I9, (CH3NH3)3SbBiI9, Ag3BiI6, Ag3BiI3(SCN)3 and Cu3BiI6 were processed by solution deposition way to be solar cells. About the structure of solar cells, we have compared the normal (n-i-p: TiO2-perovskite-spiro OMeTAD) and inverted (p-i-n: NiO-perovskite-PCBM) structures. The normal (n-i-p)-structured solar cells performed better conversion efficiencies, basically. But, these environmental friendly photon absorber layers showed the uneven surface morphology with a particular grow pattern depend on the substrate (TiO2 or NiO). We have considered that the unevenness of surface morphology can deteriorate the photovoltaic performance and can hinder future prospect of these lead-free photon harvesting layers. However, we found new interesting finding about the progress of devices by the interface of NiO/Sb3+ and TiO2/Cu3BiI6, which should be addressed in the future study
Temperature Effects on the Photovoltaic Performance of Planar Structure Perovskite Solar Cells
Enhanced Carrier Transport Distance in Colloidal PbS Quantum-Dot-Based Solar Cells Using ZnO Nanowires
Nanostructured
solar cells are a promising area of research for
the production of low cost devices that may eventually be capable
of complementing or even replacing present technologies in the field
of solar power generation. The use of quantum dots (QDs) in solar
cells has evolved from being simple absorbers in dye-sensitized solar
cells to sustaining the double functions of absorbers and carrier
transporters in full solid state devices. In this work, we use both
optical and electrical measurements to explore the diffusion limitations
of carrier transport in cells made of a heterostructure combining
lead sulfide (PbS) QDs as absorbers and hole carrier and zinc oxide
nanowires as electron carrier material. The results show efficient
charge collection along the PbS-QD/ZnO nanowire (NW) hybrid structure.
This is because of the formation of band bending in the ZnO collector,
allowing efficient charge separation and spatially well-separated
carrier pathways, yielding a hole transportation of over 1 μm.
We have also found a limitation in open-circuit voltage (<i>V</i><sub>oc</sub>) associated with band bending in the ZnO collector