春山 雄一

Abstract The impact of NiOx layers on the performance of inverted perovskite solar cells (PSCs) has been investigated using multiple analysis methods (thermal gravimetric, differential thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Soft X-ray photoelectron spectroscopy) of NiOx layers, which were made by spray pyrolysis deposition at different temperatures. The analyses of this study indicate that the efficiency of inverted PSC increases with the Scherrer crystallite size of NiOx. We also observed that the band state of the NiOx layer was changed by Na+ ions migrated from the glass substrate, which also had an impact on the efficiency. The results clearly showed that under high fabrication temperature, migration of matter from the substrate to the hole transport layer affects the electronic structure. Therefore, how these materials are engineered will be important to increase the efficiency of inverted PSCs.

Ultraviolet (UV) nanoimprinting includes a contact process necessary for transferring nanoscale features from a mold to a UV-curable resist coated on a substrate. The demolding that comes with the contact process is a source of defects, and an obstacle to be overcome for nanodevice fabrications. In this study, we aim to execute more than 10000 times of step-and-repeat UV nanoimprinting with a single mold, tracing demolding forces and water contact angles of the mold surface as the indication of mold-resist/substrate interface and mold degradation. A condensable gas, a UV-curable resist, and a fluorosurfactant were considered in this study. It was revealed that 1,1,1,3,3-pentafluoropropane (PFP) or HFC-245fa, which is the common industrial name, as a condensable gas and a type of fluorosurfactant played an important role in minimizing the demolding impact and thus helped in increasing mold lifetime. The surfactant-added resists performed 6500 imprinting steps in PFP.