伊藤 省吾

As perovskite photovoltaic devices can now compete with silicon technology in terms of efficiency, many strategies are investigated to improve their stability. In particular, degradation reactions can be hindered by appropriate device encapsulation, device architecture, and perovskite formulation. Mesoporous device architectures with a carbon electrode offer a plausible solution for the future commercialization of perovskite solar cells. They represent a low‐cost and stable solution with high potential for large‐scale production. Several studies have already demonstrated the potential of the mixed 2D/3D ammonium valeric acid iodide‐based MAPbI₃ formulation to increase the lifetime of pure MAPbI₃. They can however not describe the mechanisms responsible for the lifetime improvement. Using a full set of characterization techniques in the initial state and as a function of time during damp‐heat aging, new insights into the performance and degradation mechanisms may be observed. With (5‐AVA)_0.05MA_0.95PbI₃, the solar cells are very stable up to 3500 h and the degradation of performances essentially results from the loss of electrical contacts mainly located at the interfaces. In contrast, for the neat MAPbI₃, a poor stability is evidenced (T50 = 500 h) and the loss in performance results from the degradation of the bulk perovskite layer itself.

Proton-exchange-membrane hydrogen fuel cells (PEMFCs) are an important energy device for achieving a sustainable hydrogen society. Carbon-based catalysts used in PEMFCs’ cathode can degrade significantly during operation-voltage shifts due to the carbon deterioration. The longer lifetime of the system is necessary for the further wide commercialization of PEMFCs. Therefore, carbon-free catalysts are required for PEMFCs. In this study, highly crystallized conducting Sb-doped SnO2 (Sb-SnO2) nanoparticles (smaller than 7 nm in size) were synthesized using an ozone-assisted hydrothermal synthesis. Pt nanoparticles were loaded on Sb-SnO2 supporting particles by polyol method to be “Pt/Sb-SnO2 catalyst”. The Pt/Sb-SnO2 catalyst showed a high oxygen reduction reaction (ORR) mass activity (178.3 A g−1-Pt @ 0.9 V), compared to Pt/C (149.3 A g−1-Pt @ 0.9 V). In addition, the retention ratio from the initial value of electrochemical surface area (ECSA) during 100,000-voltage cycles tests between 1.0 V and 1.5 V, Pt/SnO2 and Pt/Sb-SnO2 catalyst exhibited higher stability (90% and 80%), respectively, than that of Pt/C catalyst (47%). Therefore, the SnO2 and Sb-SnO2 nanoparticles synthesized using this new ozone-assisted hydrothermal method are promising as carbon-free catalyst supports for PEMFCs.

Fully printable carbon-based multiporous-layered-electrode perovskite solar cells (MPLE-PSCs) are easy to fabricate and have excellent durability. In this study, the porosity of the mesoporous TiO2 layer as the electron transport layer in MPLE-PSCs was controlled by varying the particle diameter of TiO2 nanoparticles from 14 nm to 98 nm. Furthermore, the results of absorbed photon-to-current conversion efficiency, visible light reflectance spectroscopy, pore-size distribution, X-ray diffraction, field emission scanning electron microscopy, and photovoltaic parameters of MPLE-PSCs are discussed. Although the porous TiO2 layer with smaller nanoparticles showed higher photoabsorption, it was found that the more voids of perovskite crystals created in the TiO2 porous layer, the smaller the particle size (<18 nm). The porous TiO2 layers with particles over 26 nm are well filled with perovskite crystals, resulting in a higher photovoltaic capacity with TiO2 particles over 26 nm. As a result, the short-circuit current density (JSC) showed a maximum value using 43 nm TiO2 particles, with an average power conversion efficiency (PCE) of 10.56 ± 1.42%. Moreover, the PCE showed a maximum value of 12.20% by using 26 nm TiO2 nanoparticles.

Abstract The impact of NiOx layers on the performance of inverted perovskite solar cells (PSCs) has been investigated using multiple analysis methods (thermal gravimetric, differential thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Soft X-ray photoelectron spectroscopy) of NiOx layers, which were made by spray pyrolysis deposition at different temperatures. The analyses of this study indicate that the efficiency of inverted PSC increases with the Scherrer crystallite size of NiOx. We also observed that the band state of the NiOx layer was changed by Na+ ions migrated from the glass substrate, which also had an impact on the efficiency. The results clearly showed that under high fabrication temperature, migration of matter from the substrate to the hole transport layer affects the electronic structure. Therefore, how these materials are engineered will be important to increase the efficiency of inverted PSCs.

To fabricate fully printed carbon-based multiporous-layered-electrode perovskite solar cells (MPLE-PSCs), a polymer binder thickener had to be added to the carbon paste for the conductive carbon electrode. The polymer binder thickener is a key material to control the dispersion of carbon particles, viscosity for screen printing, and thickness and porosity of carbon electrodes. In this work, the role and effect of polymer binder thickeners for high-temperature carbon porous electrodes on MPLE-PSCs have been investigated in detail. Several carbon pastes with/without polymer binder thickeners (4 types of ethyl cellulose and 2 types of hydroxypropyl cellulose, which have different viscosities) were compared. What we understand in this paper are (1) Aggregation and dispersion of carbon particles are controlled by the polymer binder thickener (ethyl cellulose and/or hydroxypropyl cellulose); (2) For the porous carbon electrodes, the polymer binder thickeners are carbonized during the sintering procedure at 400 °C and can be kept on the surface of carbon particles as the additional carbon surface skin, which improves the conductivity; (3) The polymer binder thickeners can help the formation of a fine mesoporous structure in the annealed carbon electrodes. Combinations of results between viscosity, thermal, and specific surface area analyses revealed the close relationship between device performance and printability, dispersibility, and porosity brought by the polymer binder thickeners. As a result, the addition of a 20 wt % polymer binder thickener improved the average power conversion efficiency (PCE) from 9.52 ± 2.04 to 10.86 ± 0.85%, achieving a champion PCE of 12.06%.

Developing high-performance dopant-free hole transport material (DF-HTM) is critical to realizing stable perovskite solar cells (PSCs). Herein, a class of siloxane-terminated polymers (PBZ-Si) with low surface energy were studied as...

Multi-porous-layered-electrode perovskite solar cells (MPLE-PSCs) have been fabricated for the outer-space application, which should have the stability at 130 degrees C. After selection of sealing glue compounds, the thermal stability of MPLE-PSCs was improved drastically.

The effect of atomic hydrogen exposure on hydrogenated amorphous carbon (a-C:H) films was investigated by X-ray photoelectron spectroscopy (XPS). From the dependence of the wide-scan XPS spectra of an a-C:H film on atomic hydrogen exposure, it was shown that the film was etched with an etching rate of 0.2 nm min-1. In addition, by analyzing the C 1s XPS spectra, the coordination of C atoms in the a-C:H film was investigated as a function of the atomic hydrogen exposure and photoelectron emission angle. This indicated that the coordination of C atoms at the surface of the a-C:H film was not influenced by atomic hydrogen exposure. Therefore, we propose that the depth profile of a-C:H films can be measured with no damage using atomic hydrogen etching.

Improving stability has become one of the most important objectives in the practical application of perovskite photovoltaics. Here, we develop encapsulated mesoporous-carbon perovskite solar mini-modules that retain more than 92% of their initial performance after 3,000 h of damp-heat aging at 85 degrees C/85% relative humidity, while maintaining 90% of the initial value (T90) for 3,260 h, equivalent to 20-year stability in outdoor use. This stability is attributed to the light-induced performance increase phenomenon. The mechanism is associated with the organic molecules 5-ammoniumvaleric acid and methylammonium forming a quasi-2-dimensional perovskite/metal oxide interface with a positive effect on charge transport and ion migration. This work extends our present understanding of the mechanism underlying the light-induced performance and stability increase.

We applied room-temperature photoluminescence (PL) spectroscopy for the compositional engineering of a CH3NH3Pb(Cl,I)(3) light harvester in an alloy-based perovskite solar cell. This spectroscopic characterization determines the optimal Cl concentration where the power conversion efficiency shows its maximum in a contactless and non-destructive manner. The PL quenching ratio evaluated from the comparative PL studies between the films grown on glass/ZrO2 and SnO2:F/TiO2 substrates exhibited its maximum at a Cl concentration of 10 mol%, which agrees with the Cl concentration determined from the current-voltage measurement-based device performance. We also discuss the possible reasons for the coincidence mentioned above regarding the charge extraction effect induced by Cl incorporation.</p>

In this work we compare seven different types of natural and synthetic graphite particles and examine how their integration into the cathode of carbon-based perovskite solar cells (C-PSCs) is influencing their opto-electronic properties. By combining x-ray diffraction, Raman spectroscopy and 4-point probe measurements we show that the differences in graphite crystallinity significantly affect the sheet resistance of the carbon-based cathode. The most conductive carbon-based film with an exceptional sheet resistance of 4 Omega/sq. have been produced from scaly graphite with the crystallite dimensions of L-a = 60.6 nm and L-c = 28.6 nm. Electrochemical Impedance Spectroscopy further revealed that charge transfer resistance at the perovskite/carbon contact differ for each graphite type. Overall, the pyrolytic graphite was found to be the best compromise between high conductivity and low charge transfer resistance leading to least series resistance losses and a fill factor (FF) above 74% (in perovskite solar cells with area of 0.64 cm(2)). However, an overall efficient hole extraction and lower non-radiative charge recombination in C-PSCss with scaly graphite resulted in the highest average power conversion efficiency and a champion device reaching 14.63%. All the C-PSCss show exceptional moisture stability for 5,000 h under ambient condition, with a PCE decrease of less than 3%. (C) 2021 The Authors. Published by Elsevier Ltd.

<p>Ni and NiFe decorated pencil graphite rods have good performance for the oxygen evolution reaction. Capacitance data describe the redox processes of nickel and show OER activation after Ni⁴⁺ formation.</p>

We demonstrate the effect of sheet conductivity and infiltration using the example of two graphite types, showing that, in general, the graphite type is very important. Amorphous and pyrolytic graphite were applied to carbon electrodes in fully printable carbon-based multiporous-layered-electrode perovskite solar cells (MPLE-PSCs): . The power conversion efficiency (PCE) using amorphous graphite-based carbon (AGC) electrode was only 5.97% due to the low short-circuit photocurrent density (J(sc)) value, which was due to the low incident photon-to-current efficiency (IPCE) in the short wavelength region caused by the poor perovskite filling into the porous TiO2-ZrO2 layers. Conversely, using pyrolytic graphite-based carbon (PGC) electrode, J(sc), open-circuit photovoltage (V-oc), fill factors (FF), and PCE values of 21.09 mA cm(-2), 0.952 V, 0.670, and 13.45%, respectively, were achieved in the champion device. PGC had poorer wettability and a small specific surface area as compared with AGC, but it had better permeability of the perovskite precursor solution into the porous TiO2/ZrO2 layers, and therefore a denser filling and crystallization of the perovskite within the porous TiO2/ZrO2 layers than AGC. It is confirmed that the permeability of the precursor solution depends on the morphology and structure of the graphite employed in the carbon electrode.

2,2', 7,7'-Tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD) is utilized as a p-type semiconductor layer in perovskite solar cells and solid-state dye-sensitized solar cells. Spiro-OMeTAD has been known to have a spiro center, leading to a random orientation. Although the molecular orientation of organic semiconductor materials influences the conductivity, which is directly related to semiconductor device characteristics, the molecular orientation of spiro-OMeTAD has not been fully discussed. In this study, we prepared spiro-OMeTAD layers on various substrates and investigated their orientation by grazing-incidence wide-angle X-ray scattering (GIWAXS) and near-edge X-ray absorption fine structure (NEXAFS). Additionally, we demonstrated that the molecular orientation of spiro-OMeTAD could be controlled by changing their surface energies by changing the substrate materials. Consequently, we could improve the electrical conductivity by improving its molecular orientation. The results of this study provide a guideline for the preparation of organic semiconductor material layers using the wet-coating method.

Control of lymphocyte infiltration in kidney is a potential therapeutic strategy for lupus nephritis, considering that control of lymphocyte migration by sphingosine 1 phosphate has been implicated in inflammation-related pathology. The peptide inhibitor of the transendothelial migration (PEPITEM)/cadherin (CDH) 15 axis was recently reported to promote sphingosine 1 phosphate secretion. In this study, we investigated whether CDH15 is expressed in the kidney of MRL/lpr mice and whether lymphocyte infiltration is suppressed by exogenously administered PEPITEM. Mice (18 wk old) were randomized into 4-wk treatment groups that received PEPITEM or PBS encapsulated in dipalmitoylphosphatidylcholine liposomes. Enlargement of the kidney, spleen, and axillary lymph nodes was suppressed by PEPITEM treatment, which also blocked infiltration of double-negative T lymphocytes into the kidney and glomerular IgG/C3 deposition, reduced proteinuria, and increased podocyte density. Immunohistochemical analysis revealed that the PEPITEM receptor CDH15 was expressed on vascular endothelial cells of glomeruli and kidney arterioles, skin, and peritoneum in lupus mice at 22 wk of age but not in 4-wk-old mice. These results suggest that PEPITEM inhibits lymphocyte migration and infiltration into the kidney, thereby preserving the kidney structure and reducing proteinuria. Thus, PEPITEM administration may be considered as a potential therapeutic tool for systemic lupus erythematosus.

Copyright © 2020 American Chemical Society. An inexpensive, simple, and high-activity catalyst preparation method has been introduced in this work. Pt and RuOx catalysts were fabricated by soaking inexpensive graphite electrodes (pencil-lead graphite rod: PGR) in catalyst precursor solutions and using a simple flame-annealing method, which results in lower amount of Pt and RuOx catalyst layers. From X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure analysis, it has been found that platinum and ruthenium were deposited as zero-valence metal (Pt) and oxide (RuOx), respectively. Catalytic activities of Pt/PGR and RuOx/PGR for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were evaluated using neutral 1 M Na2SO4 aqueous electrolyte, respectively. Although HER and OER currents using PGR without catalysts were -16 mA cm-2 (at -1.5 V vs Ag/AgCl) and +20 mA cm-2 (at +2.0 V vs Ag/AgCl), they were improved to -110 and +80 mA cm-2 with catalysts (Pt and RuOx), respectively. Such an inexpensive and rapid catalyst electrode preparation method on PGR using flame-annealing is a very significant method in the initial catalyst activity evaluation requiring a large amount of trial and error.

Improvement of aluminum alloyed p + back surface fields (p + BSF) which is an essential requirement for achieving high efficiency silicon solar cells has been an important task. One of the ways to have better quality BSFs can be to introduce screen printable aluminum pastes with boron content. Two type of pastes were developed in this work and recipes were provided in detail: screen-printable aluminum paste without boron content (B-free-Al-paste), screen-printable aluminum paste with boron content (Al-B-paste). The ingredients of the pastes were optimized and basically evaluated in terms of alloying and impurity characteristics by measurement of sheet resistances, carrier lifetimes and SIMS analysis. Carrier lifetimes of the wafers processed by Al-B-paste maintained at around 300 mu s relatively higher than the wafers processed by B-free-Al-paste. P-type silicon solar cells were fabricated using developed pastes and were compared with those of the cells fabricated by commercial aluminum pastes. Best efficiency of 17.8% was achieved with totally vacuum-less cell production process and Suns-Voc analysis were also carried out for fabricated solar cells.

A new optical anomaly has been found in photoreflectance spectra at temperatures above 250 K at spray-pyrolysis-deposited junctions composed of F-doped SnO2 and anatase TiO2 junctions. The energetic position of this anomaly at room temperature is considerably lower than those associated with the bulk optical transitions of TiO2. Its intensity monotonically grows against the temperature rise. These experimental facts suggest that the new anomaly comes from optical transition from the valence band of TiO2 to midgap interface states. (C) 2019 The Japan Society of Applied Physics

Variations in the time courses of the activation of fully-printable carbon-based multi-porous-layered-electrode perovskite solar cells (MPLE-PSCs) can lead to differences between the photocurrent density (J(sc)) values obtained from one-sun photocurrent density-voltage (J-V) measurements and from incident-photon-to-current efficiency (IPCE) integration when using monochromic light. In the present work, the J(s)(c). calculated from IPCE data was initially equal to half that obtained from one-sun J-V measurements. However, equivalent values were obtained when the J-V measurements were performed after 10 min of irradiation by a white light LED from the side of the device. This finding will be very important with regard to permitting accurate photovoltaic evaluation of MPLE-PSCs in the future. (C) The Author(s) 2020. Published by ECSJ.

Copyright © 2019 American Chemical Society. Inexpensive and sensitive graphite electrodes were fabricated by applying flame annealing to pencil-graphite rods (PGRs) as electrodes for water electrolysis cells. The resin (polymer, binder) on the surface of PGR was removed by flame annealing to make it porous, and the graphite electrodes with high activity and low cost were obtained. By flame annealing the PGR, although the PGR electrode became active upon water electrolysis, the PGR electrode became instable for long-time operation. The effects of flame annealing on PGR for water electrolysis were analyzed by SEM, FT-IR spectroscopy, Raman spectroscopy, NEXAFS, and electrochemical impedance spectroscopy (EIS).

In the inverted structure perovskite solar cells, a buffer layer is generally used at the interface between the n-type semiconductor layer and the metal electrode, but its design guidelines have not yet been established. Here, a series of inverted perovskite solar cells have been fabricated with the controlled thickness of bathocuproine (BCP) buffer layers deposited by thermal evaporation and validated the BCP buffer layer evaluation tool. The ideal factor was calculated from the gradient in the plot of Voc against the log of Jsc, and the effect of the BCP buffer layer on charge recombination was verified. Since the ideal factor greatly decreased from 5 to 1.4 by introducing the BCP buffer layer, it was confirmed that the interface between the n-type semiconductor layer and the metal electrode gradually changed from a Schottky barrier diode to an ohmic contact. On the other hand, it was found that an excessive BCP film thickness causes the series resistance to increase and induced recombination. Finally, as a result of optimizing the perovskite layer and the BCP buffer layer, respectively, the performance exceeding 17% was obtained. This study provides insight into the improvements in the conversion efficiency of perovskite solar cells by optimizing the thickness of the buffer layer using the ideal factor. (C) 2019 Author(s).

Electronic states of a free-standing hydrogenated monolayer boron (HB) sheet were studied via soft X-ray spectroscopies at the B K-shell absorption edge and first-principles calculations. The HB sheet is semimetallic with electron and hole pockets at the Y and Γ points, respectively. The electron band results from the B-H-B bonds formed during synthesis from a MgB2 crystal, while the hole band is kept through the process and originates from a honeycomb lattice boron layer or borophene in MgB2. Our results suggest that the HB sheet is a promising two-dimensional material for realizing new boron-based or superconducting nanodevices.

Organic-inorganic CH3NH3PbI3-based perovskite solar cells have received significant research interest; however, thermal stability issue still remains. Carbon-based triple-porous-layer perovskite solar cells without any hole transporting material were selected in order to investigate the internal degradation process by thermal stresses. The sealed perovskite solar cells at 100 degrees C showed stable performance in the power conversion efficiency up to 4500 h, but the degradation was accelerated after that. By analyzing the perovskite solar cells aged for 7000 h at 100 degrees C, the results of energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy suggest that, although Pb, I, and N were sealed inside of the devices, a plenty amount of CH3NH3+ deactivated in the sealant UV-curable adhesive at 100 degrees C, which is the reason of the thermal degradation for the sealed perovskite solar cells.

Organic methyl ammonium lead halide crystal (e.g. CH3NH3PbI3) can be Perovskite structure with good semiconductor characteristics for solar cells over 24% photoenergy conversion efficiency. The significant point of the perovskite crystal is that it can be prepared by printing methods on substrates (e.g. spin coating doctor blading. ink jet printing and so on). However, the physical phenomena of perovskite solar cells are still rut clear for the higher conversion efficiency and higher stability against circumstances. in order to manage the issues. synchrotron soft X-ray can be a quite strung tool for the analysis. In this conference, the points about how to use synchrotron soft X-ray on perovskite solar cells will be discussed.

Aluminum acetylacetonate-based AlOx thin films were introduced as a low-cost, high-quality passivation layers for crystalline silicon solar cells. Films were formed by a spin coating method on p-type silicon substrates at 450 degrees C in ambient air, O-2, or water vapor (H2O/O-2) for 15 or 120 min. XPS analysis confirms the AlO2 formation and reveals a high intensity of interfacial SiOx at the AlO2/Si interface of processed wafers. Ambient H2O/O-2 was found to be more beneficial for the activation of introduced AlO2 passivation films which offers high lifetime improvements with a low thermal budget. Carrier lifetime measurements provides that symmetrically coated wafers reach 119.3 mu s and 248.3 mu s after annealing in ambient H2O/O-2 for 15 min and 120 min, respectively.

Fully non-vacuum processed perovskite solar cells have been demonstrated using cheap inorganic copper(i) thiocyanate (CuSCN) as an efficient hole transporting layer in conjunction with low temperature processed carbon back electrodes. The CuSCN interlayer attained better energetic matching and assisted the easy release of holes, reducing the observed hysteresis. The fabricated PSC (F-doped SnO2 glass (FTO)/dense TiO2/porous TiO2/CH3NH3PbI3/CuSCN/carbon) was able to realize a power conversion efficiency (PCE) of 12.41%, measured under 100 mW cm(-2) illumination with a short circuit current density of 18.90 mA cm(-2), an open circuit voltage of 0.95 V and a fill factor of 0.68. An advantageous 68% of the initial PCE was retained for the unencapsulated PSC stored in air in the dark, measured over 4500 h. Although PSCs without a CuSCN interface retain their initial PCE after 185 days of ambient storage and 1000 h of dark thermal stress (85 degrees C), the PCEs of perovskite solar cells with CuSCN undergo significant deterioration.

The Optical and electrical effects of the transparent conductive oxide layer on the performance of inverted perovskite solar cells (PSCs) were investigated. We have utilized transparent conductive layers of ITO and FTO layers with the same sheet resistance. The PSCs with ITO-coated glass achieved the 10.8% conversion efficiency, which is higher than that with FTO one (9.0%). The first finding is that the PSCs with ITO-coated glass substrate has lower resistances in series and parallel than those with ITO coated one. The second finding is that ITO-coated glass substrate has a higher transmittance than FTO, the PSCs with ITO-coated glass substrate can obtain the high IPCE value. PSCs using FTO-coated glass substrate did not show hysteresis in the I-V curves. However, hysteresis was caused using ITO-coated glass substrate, due to the slight differences between ITO and FTO about the roughness of the HTL interface in contact with the perovskite layer.

Perovskite and textured silicon solar cells were integrated into a tandem solar cell through a stacking method. To consider the effective structure of silicon solar cells for perovskite/silicon tandem solar cells, the optic and photovoltaic properties of textured and flat silicon surfaces were compared using mechanical-stacking-tandem of two- and four-terminal structures by perovskite layers on crystal silicon wafers. The reflectance of the texture silicon surface in the range of 750-1050 nm could be reduced more than that of the flat silicon surface (from 2.7 to 0.8%), which resulted in increases in average incident photon to current conversion efficiency values (from 83.0 to 88.0%) and current density (from 13.7 to 14.8 mA/cm(2)). Using the texture surface of silicon heterojunction (SHJ) solar cells, the significant conversion efficiency of 21.4% was achieved by four-terminal device, which was an increase of 2.4% from that of SHJ solar cells alone.

Small-sized single crystalline silicon solar cells (ca. 25 mm(2)) were fabricated by a non-vacuum process as an energy supply for small devices (ubiquitous devices: a wristwatch, desktop calculator etc.) and processed for a tandem solar-cell research. A side-edge etching procedure was performed in order to eliminate detrimental cracks to improve photovoltaic properties. Moreover, the new structure of the small-sized solar cell with side contact provides reduced shadow loss of contacts. After the structural and procedural optimization, a conversion efficiency of 16.4% was achieved by a non-vacuum process with 3 mm x 8 mm surface dimension solar cell. Finally, the photovoltaic characteristics of small silicon cells, as a function of light intensity for the ubiquitous purposes were compared with amorphous silicon solar cells. In addition, the facile processed silicon solar cell was integrated into mechanically-stacked tandem solar cells with perovskite solar cells by direct contact of TCO layers of each sub-cell. The counter electrode MoOX/IZO over HTM (spiro-OMeTAD) in top perovskite cells is physically placed on top of the bottom Si solar cell to form a series tandem configuration. (C) 2017 Elsevier Ltd. All rights reserved.

The present work addresses two important aspects; (i) crystalline formation of perovskites by fast powder production method (FPP) in large scale and its corresponding analysis and (ii) fabrication of mixed cation perovskite solar cells (PSC) by conventional one step method using inorganic copper (I) thiocyanate (CuSCN) as hole transport material (HTM). In this work, we investigate a stable and stoichiometrically variable Cs content in powdered MAPbI(3) perovskites. For the first time, distinct morphologies like porous sheets, nanorods and nanowires, tightly bonded grains and fibre structures are collectively observed for the various concentrations of the Cs mixed with MAPbI(3) by the FPP method, which finds applications in optoelectronic, energy and memory devices. In place of using expensive organic HTM, in this study, CuSCN is utilized as HTMs due to their cost and humidity resistance for the application to solar cells. The highest efficiency so far attained using CuSCN HTM in Cs(x)MA(1-x)PbI(3) composite PSC is being discussed. (C) 2017 Elsevier Ltd. All rights reserved.

Fibrous nanomaterials have been widely employed toward the improvement of photovoltaic devices. Their light-trapping capabilities, owing to their unique structure, provide a direct pathway for carrier transport. This paper reports the improvement of perovskite solar cell (PSC) performance by a well-dispersed TiO2-coated gold nanowire (GNW) in a TiO2 cell layer. We used an artificially designed cage-shaped protein to synthesize a TiO2-coated GNW in aqueous solution under atmospheric pressure. The artificially cage-shaped protein with gold-binding peptides and titaniumcompound-biomineralizing peptides can bind GNWs and selectively deposit a thin TiO2 layer on the gold surface. The TiO2-coated GNW incorporated in the photoelectrodes of PSCs increased the external quantum efficiency within the range of 350-750 nm and decreased the internal resistance by 12%. The efficient collection of photogenerated electrons by the nanowires boosted the power conversion efficiency by 33% compared to a typical mesoporous-TiO2-nanoparticle-only electrode.

In this work, we introduce a totally vacuum-free cost-efficient crystalline silicon solar cells. Solar cells were fabricated based on low-cost techniques including spin coating, spray pyrolysis, and screen-printing. A best efficiency of 17.51% was achieved by non-vacuum process with a basic structure of <AI/p+/p-Si/n+/SiO2/TiO2/Ag> CZ-Si p-type solar cells. Short circuit current density (J(SC)) and open circuit voltage (V-OC) of the best cell were measured as 38.1 mAcm(-2) and 596.2 mV, respectively with fill factor (FF) of 77.1%. Suns-Voc measurements were carried out and the detrimental effect of the series resistance on the performance was revealed. It is concluded that higher efficiencies are achievable by the improvements of the contacts and by utilizing good quality starting wafers.

In this article, we demonstrate for the first time a mesoscopic printable perovskite solar cell (PSC) using NiO as the hole transporting material and low-temperature processed carbon as the counter electrode. A single deposition method assisted by N-2 blow drying was used for the deposition of MAPbI(3) on a TiO2/ZrO2/NiO screen-printed electrode. As the final step a low-temperature processing (i.e. 75 degrees C) carbon counter layer was fabricated on MAPbI(3) by a blade coating method. It is found that the capping layer thickness of MAPbI(3) has a significant effect on the device efficiency, especially when NiO is introduced as a hole transporting material into the structure. Electrochemical impedance spectroscopy demonstrates good charge transport characteristics for the device with a thin MAPbI(3) capping layer obtained by the N-2 blow drying method. Our best performing device demonstrated a remarkable photovoltaic performance with a short-circuit current density (J(sc)) of 22.38 mA cm(-2), an open circuit voltage (V-oc) of 0.97 V, and a fill factor (FF) of 0.50 corresponding to a photo-conversion efficiency (PCE) of 10.83%. Moreover, the un-encapsulated device exhibited advantageous stability over 1000 h in air in the dark.

Herein, we studied the effect of MgO coating thickness on the performance of printable perovskite solar cells (PSCs) by varying the electrodeposition time of Mg(OH)(2) on the fluorine-doped tin oxide (FTO)/TiO2 electrode. Electrodeposited Mg(OH)(2) in the electrode was confirmed by energy dispersive X-ray (EDX) analysis and scanning electron microscopic (SEM) images. The performance of printable PSC structures on different deposition times of Mg(OH)(2) was evaluated on the basis of their photocurrent density-voltage characteristics. The overall results confirmed that the insulating MgO coating has an adverse effect on the photovoltaic performance of the solid state printable PSCs. However, a marginal improvement in the device efficiency was obtained for the device made with the 30 s electrodeposited TiO2 electrode. We believe that this undesirable effect on the photovoltaic performance of the printable PSCs is due to the higher coverage of TiO2 by the insulating MgO layer attained by the electrodeposition technique.

Developing low cost CH3NH3PbI3 solar cell utilising earth abundant carbon as a counter electrode in the hole transport layer free structure is promising for practical applications. Here we demonstrated the solution processed CH3NH3PbI3 solar cells by utilising ambient coated carbon layer as hole transport and counter electrodes. The fabricated devices exhibit the advantages in terms of ambient and high temperature (85 degrees C) thermal stability which is an essential according to IEC 61646 climate chamber test norms.

In order to achieve high-efficiency solar cells, a tandem structure with perovskite and silicon solar cells was introduced and concerned, recently. However, it was difficult to form perovskite top cell on "textured" silicon solar cell due to the inhomogeneity layer of perovskite top cells by solution process. In this work, therefore, in order to combine perovskite solar cell as a top cell and "textured" silicon heterojunction (SHJ) solar cell as a bottom cell, the top and bottom cell were integrated into the two-terminal tandem solar cells by mechanically stacking as the first time. Moreover, energy bandgap of perovskite layer was controlled by containing bromine to achieve current matching between top and bottom cell.

We developed lead-free perovskite solar cells, because lead is harmful to the human body. In this study, the lead-free perovskite layers were fabricated using antimony, bismuth and silver. Normal (n-i-p) and inverse (p-i-n) structures were tried for the solar cells. By using a lead-free perovskite with silver and bismuth for the normal structure, conversion efficiency of 0.892% was achieved.

In perovskite solar cells (PSCs), electron selective layers (ESLs) assume a crucial role in blocking holes and transporting electrons for high performances. To achieve low-temperature solution processing of PSCs, organic n-type materials such as fullerene-based molecules have recently been employed to replace a typical TiO2 ESL that requires high temperature (>450 degrees C) for fabrication. Herein, soluble C-60-9-methylanthracene mono-adduct (C-60(9MA)) is used as a thermal precursor to the C-60 ESL in planar PSCs. The best performing PSC device shows a power conversion efficiency of 15.0% under the simulated AM 1.5G one sun illumination, which is superior to that of the device with compact TiO2 as an ESL (12.9%). Remarkably, a fill factor of the C-60-based PSC (0.723) is enhanced compared to that of the TiO2-based one (0.671) owing to the low charge-transfer resistance at the interface of C-60-perovskite. These results suggest that the thermal precursor approach to pristine fullerene films is a promising approach for fabricating ESL in high-performance PSCs with relatively low fabrication temperature (<140 degrees C). (C) The Author(s) 2017. Published by ECS.

Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300nm and 1100 nm) was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1) without antireflection coating (ARC) layer, (2) with TiO2-compact ARC film, and (3) with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88%) owing to themultilayer ARC. J(sc) was improved further by 2mA cm(-2) (from 35.3 mA cm(-2) to 37.2 mA cm(-2)) when compared with a single TiO2-compact ARC.

Research of CH(3)NH(3)Pbl(3) 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)(3)Bi2I9, (CH3NH3)(3)Sb2I9, (CH3NH3)(3)SbBiI9, 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: TiO-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.

We confirmed the influence of ZnO nanoparticle size and residual water on performance of all inorganic perovskite solar cells. By decreasing the size of the ZnO nanoparticles, the short-circuit current density (JSC) and open circuit photovoltage (VOC) values are increased and the conversion efficiency is improved. Although the VOC value is not affected by the influence of residual water in the solution for preparing the ZnO layer, the JSC value drops greatly. As a result, it was found that it is important to use the oxide nanoparticles with a small particle diameter and to reduce the water content in the oxide forming material in order to manufacture a highly efficient all inorganic perovskite solar cells.

Tin-doped indium oxide (ITO) sputtering is known as a damaging cause on organic hole transporting material in solar cells. In order to gain more insights into the reasons for poor device performance of perovskite solar cells by the ITO sputtering on Spiro-OMeTAD, here we present an in-depth study by I-V simulation analysis using corresponding equivalent circuit models. First, experimental I-V data were obtained for the perovskite solar cells with (FTO/TiO2(dense)/TiO2(mesoporous)/CH3NH3PbI3/Spiro-OMeTAD/ITO/Au) configuration. An Au layer (t = SO nm) was deposited on the ITO as a contact layer. The simulation studies indicated that sputtering of ITO onto Spiro-OMeTAD introduced a reverse Schottky diode and an additional diode to the device that could be relating the sputtering damage of the Spiro-OMeTAD layer. By considering the parameter of the reverse diode element as a function of sputtering time, it was found that the barrier height of the reverse Schottky diode was enhanced by the sputtering damage against Spiro-OMeTAD, which could be the key reason for the reduced fill factor of the devices.

Engineering of photonics for antireflection and electronics for extraction of the hole using 2.5 nm of a thin Au layer have been performed for two- and four-terminal tandem solar cells using CH3NH3PbI3 perovskite (top cell) and p-type single crystal silicon (c-Si) (bottom cell) by mechanically stacking. Highly transparent connection multilayers of evaporated-Au and sputtered-ITO films were fabricated at the interface to be a point-contact tunneling junction between the rough perovskite and flat silicon solar cells. The mechanically stacked tandem solar cell with an optimized tunneling junction structure was (perovskite for the top cell/Au (2.S nm)/ITO (154 nm) stacked-on ITO (108 nm)/c-Si for the bottom cell). It was confirmed the best efficiency of 13.7% and 14.4% as two and four-terminal devices, respectively.

The CH3NH3PbI3 perovskite solar cells have been fabricated using three-porous-layered electrodes as, hglass/F-doped tin oxide (FTO)/dense TiO2/porous TiO2-perovskite/porous ZrO2-perovskite/porous carbon-perovskitei for light stability tests. Without encapsulation in air, the CH3NH3PbI3 perovskite solar cells maintained 80% of photoenergy conversion efficiency from the initial value up to 100 h under light irradiation (AM 1.5, 100 mW cm(-2)). Considering the color variation of the CH3NH3PbI3 perovskite layer, the significant improvement of light stability is due to the moisture-blocking effect of the porous carbon back electrodes. The strong interaction between carbon and CH3NH3PbI3 perovskite was proposed by the measurements of X-ray photoelectron spectroscopy and X-ray diffraction of the porous carbon-perovskite layers.

A push-pull porphyrin dimer with multiple electron donating groups has been synthesized as a sensitizer with an excellent light-harvesting ability in the near-infrared region for dye-sensitized solar cells (DSSCs). The DSSC based on the sensitizer exhibited the photocurrent generation exceeding a wavelength of 900nm, together with a power conversion efficiency of 6.21% under AM 1.5 condition.

Due to the high conversion efficiency, organic-inorganic hybrid perovskite (CH3NH3PbI3) solar cells are investigated for new practical energy resources for our future society. However, the perovskite solar cells have been quite unstable devices. In this manuscript, the history of perovskite solar cells is introduced, and then, the efforts to improve and understand the stability issue of perovskite solar cells are summarized. (C) 2016 Author(s).