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[5p-PA3-24] Low temperature preparation of a mesoporous layer of perovskite solar cell using TiO2 super fine nano particles with a size smaller than 10 nm
Keywords:perovskite solar cell, Low temperature coating
Perovskite solar cells achieving high energy conversion efficiency have some types of structure configuration, nano-structured type, planar heterojunction type, inverse structure type and etc. Among them, the nanostructured type having a mesoporous titanium oxide layer formed by high-temperature sintering is often used. We have focused on the low-temperature coating processes of the TiO2 mesoporous layer utiliezed by brookite type titanium oxide having a primary particle size of 15 nm. And we have reported the energy conversion efficiency of about 20% obtained by low-temperature process lower than 150 degree Celsius. If the processes are carried out at 150 ° C. or less, perovskite solar cells can be made on a plastic substrate. This means that the roll-to-roll manufacturing processes will be possible. The basic mechanism of low-temperature coating of TiO2 nano-particles is that TiO2 nano particles are connected by a dehydration condensation reaction from an acidic aqueous sol containing highly crystalline titanium oxide nanoparticles during the solvent removing.
We have been studying high-quality titanium oxide film by this low temperature processes. It is expected that the low temperature coating process would be carried out effectively when the particle size is small having a large surface area.
Therefore, in this study, a low temperature TiO2 film preparation was carried out by using a highly dispersed neutral sol containing ultrafine anatase type titanium oxide particles with a primary particle size of 5 nm or less. A 0.5 wt% aqueous dispersion of titanium oxide was coated on a FTO glass having a compact layer formed thereon by a spin coating method and then dried at 150 ° C. for 1 hour to obtain a mesoporous titanium oxide layer having a thickness of about 50 nm. Followed by the mesoporous layer coating, a DMF solution of CH3NH3I / PbI2 / DMSO was coated by spin coating, and spiro-OMeTAD, a gold electrode were coated on the perovskite layer. As a result, a cell made by this procedure show the open voltage was 1.06 V and the conversion efficiency in reverse scan was 17.6%. This result indicate that low temperature TiO2 mesoporous layer coating process using ultrafine titanium oxide will be utilized in making highly efficient perovskite solar cells.
We have been studying high-quality titanium oxide film by this low temperature processes. It is expected that the low temperature coating process would be carried out effectively when the particle size is small having a large surface area.
Therefore, in this study, a low temperature TiO2 film preparation was carried out by using a highly dispersed neutral sol containing ultrafine anatase type titanium oxide particles with a primary particle size of 5 nm or less. A 0.5 wt% aqueous dispersion of titanium oxide was coated on a FTO glass having a compact layer formed thereon by a spin coating method and then dried at 150 ° C. for 1 hour to obtain a mesoporous titanium oxide layer having a thickness of about 50 nm. Followed by the mesoporous layer coating, a DMF solution of CH3NH3I / PbI2 / DMSO was coated by spin coating, and spiro-OMeTAD, a gold electrode were coated on the perovskite layer. As a result, a cell made by this procedure show the open voltage was 1.06 V and the conversion efficiency in reverse scan was 17.6%. This result indicate that low temperature TiO2 mesoporous layer coating process using ultrafine titanium oxide will be utilized in making highly efficient perovskite solar cells.