The Role of Thickness Control and Interface Modification in Assembling Efficient Planar Perovskite Solar Cells (original) (raw)
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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...
Nanomaterials, 2019
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.
Advanced Science
Organic–inorganic perovskite solar cells (PSCs) have achieved great attention due to their expressive power conversion efficiency (PCE) up to 25.7%. To improve the photovoltaic performance of PSCs, interface engineering between the perovskite and hole transport layer (HTL) is a widely used strategy. Following this concept, benzyl trimethyl ammonium chlorides (BTACls) are used to modify the wet chemical processed perovskite film in this work. The BTACl‐induced low dimensional perovskite is found to have a bilayer structure, which efficiently decreases the trap density and improves the energy level alignment at the perovskite/HTL interface. As a result, the BTACl‐modified PSCs show an improved PCE compared to the control devices. From device modeling, the reduced charge carrier recombination and promoted charge carrier transfer at the perovskite/HTL interface are the cause of the open‐circuit (Voc) and fill factor (FF) improvement, respectively. This study gives a deep understanding f...
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 .
Understanding the Influence of Interface Morphology on the Performance of Perovskite Solar Cells
Materials (Basel, Switzerland), 2018
In recent years, organo-halide perovskite solar cells have garnered a surge of interest due to their high performance and low-cost fabrication processing. Owing to the multilayer architecture of perovskite solar cells, interface not only has a pivotal role to play in performance, but also influences long-term stability. Here we have employed diverse morphologies of electron selective layer (ESL) to elucidate charge extraction behavior in perovskite solar cells. The TiO₂ mesoporous structure (three-dimensional) having varied thickness, and nanocolumns (1-dimensional) with tunable length were employed. We found that a TiO₂ electron selective layer with thickness of about c.a. 100 nm, irrespective of its microstructure, was optimal for efficient charge extraction. Furthermore, by employing impedance spectroscopy at different excitation wavelengths, we studied the nature of recombination and its dependence on the charge generation profile, and results showed that, irrespective of the wa...
Nanotechnology, 2017
An anodized TiO2 interconnected network was fabricated and utilized as a mesoporous scaffold and electron transporter in perovskite solar cells. By modifying the synthesis parameters, the morphological features of the interconnected TiO2 nanostructures can be widely tuned and precisely controlled. The functional properties of the anodized TiO2 network are found to be severely influenced by morphology as well as the extent of oxidation. The device with the optimized TiO2 network exhibits superior electron extraction and transferability, resulting in conspicuous enhancement of the photocurrent and power conversion efficiency (PCE). This work proposes a promising and facile method for improving the performance of perovskite solar cells.
Solar RRL, 2018
The electron-transporting layer (ETL) plays a critical role in improving the charge extraction and suppressing the carrier recombination in planar perovskite solar cells (PSCs). Compact titanium dioxide (TiO 2) film is a widely used as an ETL in conventional n-i-p PSCs. However, there is still much room for improvement in the electron mobility and reducing the oxygen vacancies of the compact TiO 2 film. Herein, Pt-doped TiO 2 film with outstanding electron-transporting property and complete coverage on the substrates is reported by the authors. Pt-doping results in a tailed band level of TiO 2 , which could suppress the charge accumulation at the interface of TiO 2-Pt/perovskite. Consequently, TiO 2-Pt ETL based PSCs deliver a power conversion efficiency as high as 20.05% with an open-circuit voltage of 1.15 V, a fill factor of 0.75, a short-circuit current density of 23.83 mA cm À2 and remarkably alleviated hysteresis behavior.
2018
This thesis investigates the n-i-p planar hybrid perovskite solar cell of structure glass-ITO / compact TiO2-Cl / (FAPbI3)0.85(MAPbBr3)0.15 / spiro-OMeTAD / Au. The main focus is on the investigation of the TiO2-Cl nanocrystal electron transport layer. In particular, the influence on the solar cell performance of varying the type of dispersion solvent used, the thickness of the layer and dispersion concentration is investigated. It has been found that using hydrous MeOH instead of anhydrous MeOH as co-solvent for dispersing the nanocrystals decreases the average PCE by 4.32%. Then, by increasing the TiO2-Cl layer thickness from 22 nm to 44 nm increases the average PCE with 5.31%. Additionally, decreasing the TiO2-Cl dispersion concentration from 20 mg/mL to 15 mg/mL in Chloroform:MeOH solvents increases the average PCE by 0.74%.