Following pioneering work1, solution-processable organic–inorganic hybrid perovskites—such as CH3NH3PbX3 (X = Cl, Br, I)—have attracted attention as light-harvesting materials for mesoscopic solar cells2,3,4,5,6,7,8,9,10,11,12,13,14,15. So far, the perovskite pigment has been deposited in a single step onto mesoporous metal oxide films using a mixture of PbX2 and CH3NH3X in a common solvent. However, the uncontrolled precipitation of the perovskite produces large morphological variations, resulting in a wide spread of photovoltaic performance in the resulting devices, which hampers the prospects for practical applications. Here we describe a sequential deposition method for the formation of the perovskite pigment within the porous metal oxide film. PbI2 is first introduced from solution into a nanoporous titanium dioxide film and subsequently transformed into the perovskite by exposing it to a solution of CH3NH3I. We find that the conversion occurs within the nanoporous host as soon as the two components come into contact, permitting much better control over the perovskite morphology than is possible with the previously employed route. Using this technique for the fabrication of solid-state mesoscopic solar cells greatly increases the reproducibility of their performance and allows us to achieve a power conversion efficiency of approximately 15 per cent (measured under standard AM1.5G test conditions on solar zenith angle, solar light intensity and cell temperature). This two-step method should provide new opportunities for the fabrication of solution-processed photovoltaic cells with unprecedented power conversion efficiencies and high stability equal to or even greater than those of today’s best thin-film photovoltaic devices.
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We thank M. Marszalek for recording SEM images, M. Tschumi for help with the stability measurements and K. Schenk for the XRD characterization. We acknowledge financial support from Aisin Cosmos R&D Co., Ltd, Japan; the European Community’s Seventh Framework Programme (FP7/2007-2013) ENERGY.2012.10.2.1; NANOMATCELL, grant agreement no. 308997; the Global Research Laboratory Program, Korea; the Center for Advanced Molecular Photovoltaics (award no. KUS-C1-015-21) of King Abdullah University of Science and Technology; and Solvay S.A. M.K.N. thanks the World Class University programmes (Photovoltaic Materials, Department of Material Chemistry, Korea University), funded by the Ministry of Education, Science and Technology through the National Research Foundation of Korea (R31-2008-000-10035-0). M.G. thanks the Max Planck Society for a Max Planck Fellowship at the MPI for Solid State Research in Stuttgart, Germany; the King Abdulaziz University, Jeddah and the Nanyang Technolocal University, Singapore for Adjunct Professor appointments; and the European Research Council for an Advanced Research Grant (ARG 247404) funded under the “Mesolight” project.
This file contains Supplementary Figures 1-5 and Supplementary Table 1.
About this article
Perovskite-polymer composite cross-linker approach for highly-stable and efficient perovskite solar cells
Nature Communications (2019)