Double functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuiting

• Main Authors: Govindhasamy Murugadoss, Gai Mizuta, Soichiro Tanaka, Hitoshi Nishino, Tomokazu Umeyama, Hiroshi Imahori, Seigo Ito
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2014-08-01
• Series: APL Materials
• Online Access: http://dx.doi.org/10.1063/1.4891597

In order to analyze the crystal transformation from hexagonal PbI2 to CH3NH3PbI3 by the sequential (two-step) deposition process, perovskite CH3NH3PbI3 layers were deposited on flat and/or porous TiO2 layers. Although the narrower pores using small nanoparticles prohibited the effective transformation, the porous-TiO2 matrix was able to help the crystal transformation of PbI2 to CH3NH3PbI3 by sequential two-step deposition. The resulting PbI2 crystals in porous TiO2 electrodes did not deteriorate the photovoltaic effects. Moreover, it is confirmed that the porous TiO2 electrode had served the function of prohibiting short circuits between working and counter electrodes in perovskite solar cells.