Water Vapour Pressure as Main Lab Parameter to Fabricate High Efficiency Perovskite Solar Cells at Ambient Conditions
Lidia Contreras-Bernal a, Antonio Riquelme a, Juan Jesús Gallardo b, Javier Navas b, Jesús Idígoras a, Juan Antonio Anta a
a Pablo de Olavide University, Sevilla, Spain, Carretera de Utrera, km. 1, Montequinto, Spain
b Department of Physical Chemestry, Universidad de Cádiz, Puerto Real, E-11510, Spain
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Oral, Lidia Contreras-Bernal, presentation 013
DOI: https://doi.org/10.29363/nanoge.nipho.2020.013
Publication date: 25th November 2019

Although perovskite solar cells have demonstrated impressive efficiencies in research labs (above 25%), there is a need of experimental procedures to allow their fabrication at ambient conditions, which would decrease substantially manufacturing costs. However, under ambient conditions, a delicate monitoring of moisture level in the atmosphere has to be enforced to achieve efficient and highly stable devices. In this work, we show that it is the absolute content of water measured in the form of partial water vapour pressure (WVP) the only lab parameter that needs to be considered during preparation. Following this perspective, MAPbI3 perovskite films were deposited under different WVP as derived by climate-determined parameters, i.e., relative humidity (RH) and lab temperature. We found that efficient and reproducible devices can be obtained at given values of WVP. Furthermore, it is demonstrated that small temperature changes, at the same RH value, result in huge changes in performance, due to the non-linear dependence of the WVP on temperature. We have extended the procedure to accomplish high-efficient FA0.83MA0.17PbI3 devices at ambient conditions by adjusting DMSO proportion in the precursor solution as a function of WVP only. As an example of the relevance of this parameter, a WVP value of around of 1.6 kPa appears to be an upper limit for safe fabrication of high efficiency devices at ambient conditions, regardless the specific values of RH and temperature present in the lab.

We thank Junta de Andalucía for financial support via grant FQM 1851 and FQM 2310, Ministerio de Economía y Competitividad of Spain under grants MAT2013-47192-C3-3-R and MAT2016-76892-C3-2-R and Red de Excelencia “Emerging photovoltaic Technologies”. We also thank “Servicio de Microscopía Electrónica de la Universidad Pablo de Olavide”. AR thanks the Spanish Ministry of Education, Culture and Sports via a PhD grant (FPU2017-03684).

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