Highly Stable Completely Non-Vacuum Process Multi-Porous-Electrodes-Layered Perovskite Solar Cell

Abstract

Perovskite solar cells (PSCs) have achieved a photoelectric conversion efficiency of 25 % and can be manufactured only by printing and coating processes, so it expected to be commercialized. However, the organic materials used for PSCs are very unstable to water and oxygen, so long-term durability needs to be improved. Therefore, we focused on a PSCs having a three-layer structure of an electron transport layer (mesoporous TiO2), a spacer layer (mesoporous ZrO2), and a hole transport layer/electrode (Graphite). The scaffold layer of this carbon-based PCSs is manufactured by only printing, and the perovskite precursor solution is drop-cast from graphite layer and infiltration into the scaffold layer to complete the device. This PCSs can perform all of the fabrication processes under non-vacuum conditions. In addition, the thick graphite layer protects the power generation layer from the surrounding air and moisture, and has high long-term stability. In this study, in order to further improve durability and performance, PCSs were fabricated using a perovskite precursor solution using only inorganic materials under completely non-vacuum.The conductive layer of the FTO glass was removed by etching and separated, and a compact TiO2 blocking layer was formed by spray pyrolysis deposition on the FTO glass. Then, TiO2 paste and ZrO2 paste were deposited by screen printing and sintering at 500 °C. Similarly, graphite paste was printed and sintering at 400 °C. Finally, a perovskite solution was instilled from the graphite layer, the solvent was removed by drying, and the perovskite was crystallized to complete the device. The PSCs was optimized by changing the composition of the paste used for each layer, the layer thickness, and the infiltration method of the perovskite precursor solution. Various material analyzes and solar cell performance evaluations were performed.The thickness of each layer was controlled by changing the composition of the paste used for each layer and the ratio of the material to the solvent. It was found that the photoelectric conversion efficiency was highest when the TiO2 layer was around 500 nm and the ZrO2 layer was 1.5~2 μm. Also, by improving the infiltration of the precursor solution, the photoelectric conversion efficiency was greatly increased. The graphite paste used to form the graphite layer was made using several types of graphite, and we found the most suitable one for this solar cell. Figure 1