Structural Design and Characterizations for Perovskite Solar Cells

A major advance in the development of inorganic sensitizers of new types occurred in 2012: Park and Grätzel reported thin-film solid-state solar cells attaining PCE 9.7 % with a methyl ammonium lead-iodide perovskite sensitizer, CH₃NH₃PbI₃, in a mesoporous TiO₂ film (thickness 0.6 μm).¹ This perovskite sensitizer has a bandgap 1.5 eV and V_OC of this perovskite-sensitized solar cell was much greater than that of a dye-sensitized solar cell (DSSC), rendering this photovoltaic system promising for further investigations. At nearly the same time, Snaith and co-workers reported a similar perovskite, CH₃NH₃PbI₂Cl, that served as light absorber for mesoscopic thin-film solid-state solar cells to attain PCE 10.9 %,² for which the mesoporous Al₂O₃ film served as a scaffold to replace the n-type TiO₂ electron-transporting layer. In 2013, Snaith and co-workers reported a significantly enhanced PCE 12.3 % for perovskite CH₃NH₃PbI_3-xCl_x solar cells with the same device structure based on Al₂O₃.³ Concurrently the development of all solid-state mesoscopic solar cells has reached a new milestone when Grätzel,⁴ Snaith,⁵ Kelly⁶ and their co-workers reported the perovskite-based  solar cells with PCE exceeding 15 % using spiro-OMeTAD as hole transporting material. Recently, we have demonstrated that perovskite solar cells using mesoporous NiO nanocrystals as p-contact electrode material in a device configuration NiO/perovskite/PCBM attained PCE 9.5 %, giving promising perspective for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics. The great discovery of the perovskites as novel photovoltaic materials has hence opened a new channel for the development of third-generation solar cells with advantages of great efficiency, cheapness, ease of processing and great endurance. Both n-type and p-type perovskite solar cells will be introduced based on varied structural configurations of the devices.

¹ Kim, H. S.; Lee, C. R.; Im, J. H.; Lee, K. B.; Moehl, T.; Marchioro, A.; Moon, S. J.; Humphry-Baker, R.; Yum, J. H.; Moser, J. E.; Grätzel, M.; Park, N. G. Scientific Reports 2012, 2, 591.

² Lee, M. M.; Teuscher, J.; Miyasaka, T.; Murakami, T. N.; Snaith, H. J. Science 2012, 338, 643.

³ Ball, J. M.; Lee, M. M.; Hey, A.; Snaith, H. J. Energy Environ. Sci. 2013, 6, 1739.

⁴ Burschka, J.; Pellet, N.; Moon, S. J.; Humphry-Baker, R. ; Gao, P.; Nazeeruddin, M. K.; Grätzel, M. Nature 2013, 499, 316.

⁵ Liu, M.; Johnston, M. B.; Snaith, H. J. Nature 2013, 501, 395.

⁶ Liu, D.; Kelly, T. L. Nature Photon. 2014, 8, 133.