Investigating the Morphology, Optical, and Thermal Properties of Multiphase-TiO2/MAPbI3 Heterogeneous Thin-Films for Solar Cell Applications (original) (raw)
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Mesoporous titanium oxide (mp-TiO 2) thin films are effective electron transport layers in hybrid perovskite solar cells. In this work the mp-TiO 2 are obtained via spin coating by mixing titanium isopropoxide and poly (vinylpyrrolidone) (PVP). Optically uniform anatase TiO 2 thin films are formed after annealing at temperatures ≥500°C. The surface morphology shows porous structure with pore sizes of ≅15-30 nm. The volume porosity of a mp-TiO 2 thin film is estimated for the first time by using the Volume Average Theory with the experimentally measured effective refractive index of the film, and confirmed by a statistical and 3D interactive method for void volume determination in the cross sectional image of the same film. It is found that this volume porosity varies slightly, from 40.3% to 43.6%, when the spin speed is between 1000 and 2500 rpm. However, the volume porosity is significantly reduced to 33% for a very slow spin speed like 500 rpm. Using these mp-TiO 2 thin films as electron transport layers in perovskite solar cells, it is confirmed that the power conversion efficiency (PCE) of the cells is a function of both the mp-TiO 2 layer thickness and volume porosity, giving the maximum PCE in a cell sample that combines a larger thickness and higher volume porosity.
International Journal of Molecular Sciences, 2021
The energy conversion efficiency (ECE) (η), current density (Jsc), open-circuit voltage (Voc), and fill factor (ff) of perovskite solar cells were studied by using the transmittance of a nanopatterned mesoporous TiO2 (mp-TiO2) thin-film layer. To improve the ECE of perovskite solar cells, a mp-TiO2 thin-film layer was prepared to be used as an electron transport layer (ETL) via the nanoimprinting method for nanopatterning, which was controlled by the aspect ratio. The nanopatterned mp-TiO2 thin-film layer had a uniform and well-designed structure, and the diameter of nanopatterning was 280 nm. The aspect ratio was controlled at the depths of 75, 97, 127, and 167 nm, and the perovskite solar cell was fabricated with different depths. The ECE of the perovskite solar cells with the nanopatterned mp-TiO2 thin-film layer was 14.50%, 15.30%, 15.83%, or 14.24%, which is higher than that of a non-nanopatterned mp-TiO2 thin-film layer (14.07%). The enhancement of ECE was attributed to the tr...
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The mesoporous TiO2 nanoparticle-based scaffold structure is the best electron transport layer (ETL) for perovskite solar cells (PSCs) and is still used in most PSCs with optimal photovoltaic characteristics. However, the high sintering temperature of TiO2 nanoparticles required to remove binders from the TiO2 paste limits PSC application to flexible electronics. In this study, a simple interface modification process involving ethanol rinsing is developed to enhance the photovoltaic characteristics of low-temperature processed PSCs. This easy and fast technique could enable remarkable performance by PSCs by significantly increasing the fill factor and current density, leading to a power conversion efficiency more than four times that of untreated solar cells.
Solar Energy Materials and Solar Cells, 2016
In the present work we report the synthesis of highly meso-and macro-porous thin TiO 2 films as efficient scaffolds for improved performance of heterojunction solid state perovskite solar cells made in Fambient air. TiO 2 films were prepared using sol-gel process and Pluronic P-123 block copolymer as organic template while they were formed on conductive glass substrates by spin-coating method. The films were employed to the construction of very efficient perovskite solar cells made at ambient conditions where CH 3 NH 3 PbI 3 À x Cl x mixed halide perovskite was used as light harvester and P3HT polymer as hole conductor. The very rough and highly porous TiO 2 films proved to be an excellent host material for perovskite growth. The structural properties of the TiO 2 electron transport layer, thickness, particle size and porosity, strongly affected the overall conversion efficiency. The optimal structure and materials composition exhibited a notably high current density J sc of 23.8 mA/cm 2 , V oc of 0.995 V and fill factor of 0.58. These solar cells prepared under ambient conditions yielded an average power conversion efficiency of 13.7% among the best ever recorded with P3HT polymer as hole conducting material.
Improving device performance of perovskite solar cells by micro–nanoscale composite mesoporous TiO2
Japanese Journal of Applied Physics, 2017
In perovskite solar cells, the morphology of the porous TiO 2 electron transport layer (ETL) largely determines the quality of the perovskites. Here, we chose micro-scale TiO 2 (0.2 µm) and compared it with the conventional nanoscale TiO 2 (20 nm) in relation to the crystallinity of perovskites. The results show that the micro-scale TiO 2 is favorable for increasing the grain size of the perovskites and enhancing the light scattering. However, the oversized TiO 2 results in an uneven surface. The evenness of the perovskites can be improved by nanoscale TiO 2 , while the crystallinity and compactness are not as good as those of the films based on micro-scale TiO 2. To combine the advantages of both micro-scale and nanoscale TiO 2 , by mixing 0.2 µm/20 nm TiO 2 with a ratio of 1 : 2 as the composite ETL, the device average power conversion efficiency was increased to 11.2% from 9.9% in the case of only 20 nm TiO 2 .
Metal-Doped TiO2 Thin Film as an Electron Transfer Layer for Perovskite Solar Cells: A Review
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The electron transfer layer (ETL) plays a vital role in achieving high-performance perovskite solar cells (PSCs). Titanium dioxide (TiO2) is primarily utilised as the ETL since it is low-cost, chemically stable, and has the simplest thin-film preparation methods. However, TiO2 is not an ideal ETL because it leads to low conductivity, conduction band mismatch, and unfavourable electron mobility. In addition, the exposure of TiO2 to ultraviolet light induces the formation of oxygen vacancies at the surface. To overcome these issues, doping TiO2 with various metal ions is favourable to improve the surface structure properties and electronic properties. This review focuses on the bulk modification of TiO2 via doping with various metal ions concentrations to improve electrical and optical properties, charge carrier density, and interfacial electron–hole recombination, thus contributing to enhancing the power conversion efficiency (PCE) of the PSCs.
Solar Energy Materials and Solar Cells, 2015
A solid-state mesoporous titanium dioxide (mTiO 2) layer based hetero-junction solar cell, employing nanoparticles (NPs) of methyl ammonium lead iodide perovskite (CH 3 NH 3 PbI 3) as light harvesters has been studied. The optimum performance parameters of CH 3 NH 3 PbI 3 are observed as a function of sintering temperature and confirmed by X-ray diffraction analysis and UV-vis spectrophotometry. A solid-state solar cell with the sandwich structure of mTiO 2 /CH 3 NH 3 PbI 3 /Graphite paste showed a power conversion efficiency of 1.11% tested under standard Air Mass 1.5 Global (1000 W m À 2 , AM1.5G) solar spectrum. Two-diode model is used to explore the performance limiting factors of the developed solid-state perovskite solar cell.
Solar Energy, 2017
The influence of the concentration of a TiCl 4 aqueous solution used for post-treatment on the device performance of MAPbI 3-x Cl x perovskite solar cells is investigated. All cell parameters increase after treatment by TiCl 4 up to the concentration of 100 mM. The enhancement in the fill factor is mainly attributed to the decrease in the series resistance of the treated cells, which is verified via photovoltaic and electrochemical impedance spectroscopy (EIS) measurements. Moreover, more efficient transport and suppressed recombination of charges in the treated cells are observed via EIS and photoluminescence quenching experiments, leading to an increase in the short circuit current density of the treated cells. As a result, a maximum efficiency of 15.6% is achieved for the cell post-treated with 100 mM TiCl 4 solution, which is 1.25 times greater than that of the untreated cell, 12.4%.