Hiroki Sakamoto

Low temperature fabrication of perovskite solar cells with TiO2 nanoparticle layers

TiO2/CH3NH3PbI3-based photovoltaic devices were fabricated by a spin-coating method using a mixture solution. TiO2 require high-temperature processing to achieve suitably high carrier mobility. TiO2 electron transport layers and TiO2 scaffold layers for the perovskite were fabricated from TiO2 nanoparticles with different grain sizes. The photovoltaic properties and microstructures of solar cells were characterized. Nanoparticle sizes of these TiO2 were 23 nm and 3 nm and the performance of solar cells was improved by combination of two TiO2 nanoparticles

Fabrication and characterization of photovoltaic devices based on perovskite compounds with TiO2 nanoparticles

Perovskite-type photovoltaic devices were fabricated by a spin-coating method using a mixture solution. The compact and meso-porous TiO2 of the solar cells were fabricated from TiO2 nanoparticles and sol, and the photovoltaic properties and microstructures were characterized. The conversion efficiencies were improved by the combination of TiO2 nanoparticles and sol. Current density was also improved by increasing numbers of spin-coatings of meso-porous TiO2. Thick meso-porous TiO2 layers would assist the construction of perovskite layers and block of the leak current.

Effects of PbI2 addition and TiO2 electron transport layers for perovskite solar cells

TiO2/CH3NH3PbI3− x Cl x -based photovoltaic cells added with PbI2 were fabricated and investigated. The fill factor and open-circuit voltage of the cell with 16 nm TiO2 nanoparticles were increased by PbI2 addition. For the cell, the short-circuit current density and open-circuit voltage were increased by using 23 nm TiO2 nanoparticles in place of 16 nm TiO2 nanoparticles. The external quantum efficiency increased, which would be due to the improved interface between the TiO2 and perovskite layers. As a result, the conversion efficiency was improved by adding PbI2 and using 23 nm TiO2 nanoparticles. X-ray diffraction showed that the perovskite crystals changed from cubic to tetragonal, which resulted in the improved stability of the perovskite solar cell by PbI2 addition.

Fabrication and characterization of perovskite photovoltaic devices with TiO2 nanoparticle layers

TiO2/CH3NH3PbI3-based photovoltaic devices were fabricated by a spin-coating method using mixture solutions with TiO2 nanoparticles. Compact TiO2 layers were prepared from titanium diisopropoxide bis(acetyl acetonate) and TiO2 nanoparticles with different particle sizes. The performance of the photovoltaic devices was improved by sequential deposition of the TiO2 layers, which resulted in microstructural change of the perovskite layers.

Effect of surface treatment of cellulose fiber (CF) on durability of PLA/CF bio-composites

Bio-composites made of polylactic acid (PLA) matrix reinforced with cellulose fibers (CF) were prepared using a twin-screw extruder and injection molding. The CFs were coated with epoxy-based surface treatment agents. Accelerated degradation tests were carried out on these PLA/CF composites at high temperatures (60 °C) or at constant temperature and constant humidity (60 °C/70% RH), and the higher-order structure changes and degradation characteristics of the molded products were evaluated. In the accelerated degradation test at 60 °C, the thermal and mechanical properties of PLA/CF composites showed no degradation, whereas at 60 °C and 70% RH, the melting point decreased ca. 25 °C and the storage modulus with increasing elapsed time decreased more than 50%. However, the thermal and mechanical properties of the PLA/CF composites treated with low-molecular-weight epoxy did not degrade, even at the high humidity of 70% RH. These results strongly suggest that the surface treatment agent not only improves interfacial adhesion between CF and PLA but also plays an important role in inhibiting degradation of the PLA matrix.

Fabrication and characterization of CH3NH3(Cs)Pb(Sn)I3(Cl) perovskite solar cells with TiO2 nanoparticle layers

TiO2/CH3NH3(Cs)Pb(Sn)I3(Cl)-based photovoltaic cells were fabricated and investigated. The solar cells with TiO2 nanoparticles on compact TiO2 layers provided better photovoltaic performance than those without TiO2 nanoparticles on the compact TiO2 layers. The short-circuit current density and open-circuit voltage were increased by using 16 nm TiO2 nanoparticles, which resulted in improved photoelectric conversion efficiency. The external quantum efficiency increased because of the improved interface between the TiO2 layer and the perovskite layer. X-ray diffraction showed suppression of the formation of PbI2 crystals, and the coverage and grain boundary area of the perovskite crystals with 16 nm TiO2 layers were improved, which resulted in the improved performance of the perovskite solar cell.

Effects of CsBr addition on the performance of CH3NH3PbI3-xClx-based solar cells

Perovskite-type photovoltaic devices were prepared by a spin-coating method using a precursor solution of CH3NH3I and lead(II) chloride in N,N-dimethylformamide. Effects of cesium bromide (CsBr) addition on the photovoltaic properties and microstructures of the perovskite phase were investigated. The fill factor was increased by adding the CsBr to the CH3NH3PbI3-xClx precursor solution, which resulted in increase of the conversion efficiency. The crystallinity of the CH3NH3PbI3-xClx perovskite phase was also improved by adding the CsBr to the H3NH3PbI3-xClx precursor solution.Perovskite-type photovoltaic devices were prepared by a spin-coating method using a precursor solution of CH3NH3I and lead(II) chloride in N,N-dimethylformamide. Effects of cesium bromide (CsBr) addition on the photovoltaic properties and microstructures of the perovskite phase were investigated. The fill factor was increased by adding the CsBr to the CH3NH3PbI3-xClx precursor solution, which resulted in increase of the conversion efficiency. The crystallinity of the CH3NH3PbI3-xClx perovskite phase was also improved by adding the CsBr to the H3NH3PbI3-xClx precursor solution.