Photocurrent Mapping of Perovskite Solar Cells

International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics 2015 (HOPV15)

Poster, Tanja Ivanovska, 428
Publication date: 5th February 2015

The rising interest in the hybrid organic/inorganic solar cells which utilize organic metal halide perovskites as absorbers instigated a variety of research lines in order to both quantitatively and qualitatively account for the high efficiency of these types of cells. A great deal of research has been focused in understanding the connection between the configuration of the solar cell with the morphology and structure of the perovskite material^[1,2], since high efficiencies have been reported both for cells with and without a scaffold  structure for the perovskite absorber. Additionally the scaffold materials vary not only in their structural but in their dielectric/conductive properties as well. In an attempt to correlate the efficiency of the perovskite solar cell with respect to the surface coverage and morphology of the absorber material, in this case Cl doped CH₃NH₃PbI₃, we have investigated different types of perovskite solar cells; both in “flat” configuration and employing a scaffold material such as a mesoporous TiO₂ and porous alumina. We applied the LBIC technique (Laser beam induced photocurrent)^[3] in order to study locally, at the micrometric and sub-micrometric scale, the photovoltaic functioning of complete devices prepared with the above cited different configurations and scaffold materials. This noninvasive technique allows us to map the intensity of the photocurrent over the cell surface, obtaining photocurrent map images from 50x50 microns up to hundreds of microns, with a resolution of around 400 nm. Such a low resolution was obtained by coupling the laser excitation with the optics of a confocal fluorescence microscope. The analysis of the photocurrent map images allows to distinguish between separate features which can be directly associated with the different morphologies of the active layers of the cells. Correlation of optical images with the LBIC maps and the extracted information on the efficiency of the charge generation and extraction process with respect to the structure and morphology of the perovskite within the solar cell will be discussed.

[1]Eperon, G.E. et al. Morphological Control for High Performance, Solution-Processed Planar Heterojunction Perovskite Solar Cells. Adv. Funct. Mater. 2014, 24, 151–157. [2]Grancini, G. et al. The Impact of the Crystallization Processes on the Structural and Optical Properties of Hybrid Perovskite Films for Photovoltaics. J. Phys. Chem. Lett. 2014, 5, 3836–3842. [3]Seeland, M.; Rösch, R.; Hoppe, H. Imaging Techniques for Studying OPV Stability and Degradation in Stability and Degradation of Organic and Polymer Solar Cells. ed. F. C. Krebs, Wiley. 2012, ISBN: 978-1-119-95251-0.

© FUNDACIO DE LA COMUNITAT VALENCIANA SCITO