Improved Morphology and Efficiency of n-i-p Planar Perovskite Solar Cells by Processing with Glycol Ether Additives

Abstract
Planar perovskite solar cells can be prepared without high temperature processing steps typically associated with mesoporous device architectures; however, their efficiency has been lower and producing high quality perovskite films in planar devices has been challenging. Here, we report a modified two-step interdiffusion protocol suitable to prepare pin-hole free perovskite films with greatly improved morphology. This is achieved by simple addition of small amounts of glycol ethers to the preparation protocol. We unravel the impact the glycol ethers have on the perovskite film formation using in-situ UV-Vis absorbance and GIWAXS experiments. From these experiments we conclude: addition of glycol ethers changes the lead iodide to perovskite conversion dynamics and enhances the conversion efficiency, resulting in more compact polycrystalline films, and it creates micrometer-sized perovskite crystals vertically-aligned across the photoactive layer. Consequently, the average photovoltaic performance increases from 13.5% to 15.9% and reproduciability is enhanced, specifically when 2-methoxyethanol is used as additive.

Citation
Ugur E, Sheikh AD, Munir R, Khan JI, Barrit D, et al. (2017) Improved Morphology and Efficiency of n-i-p Planar Perovskite Solar Cells by Processing with Glycol Ether Additives. ACS Energy Letters. Available: http://dx.doi.org/10.1021/acsenergylett.7b00526.

Acknowledgements
This work was supported by the King Abdullah University of Science and Technology (KAUST). GIWAXS measurements were performed at D-line at the Cornell High Energy Synchrotron Source (CHESS) at Cornell University. CHESS is supported by the NSF & NIH/NIGMS via NSF award DMR-1332208.

Publisher
American Chemical Society (ACS)

Journal
ACS Energy Letters

DOI
10.1021/acsenergylett.7b00526

Additional Links
http://pubs.acs.org/doi/abs/10.1021/acsenergylett.7b00526

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