In-situ analysis of solvent extraction process for large area perovskite film formation
Xuan Li a, Stoichko Dimitrov a
a School of Physical and Chemical Sciences, Queen Mary University of London
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV23)
London, United Kingdom, 2023 June 12th - 14th
Organizers: Tracey Clarke, James Durrant and Trystan Watson
Poster, Xuan Li, 255
Publication date: 30th March 2023

Large area perovskite film deposition has been drawing considerable amount of interest to achieve the commercialization of perovskite during the past years. Differ from the conventional spin coating which normally adopts a dynamic antisolvent treatment to achieve high quality perovskite films, scale up methods require a different approach to achieve high quality films. Notoriously, dynamic antisolvent treatment for spin coating has a low reproducibility due to the manual errors such as antisolvent injection timing, injection rate, alignment, and height variations.

Here we report an antisolvent bath approach to achieve large area high quality perovskite films deposited via slot die coating with higher reproducibility. The as deposited film was placed into a customized quartz chamber filled with different antisolvent; a custom-made in-situ analysis equipment was used to monitor the photoluminescence (PL) and transmittance evolution of the perovskite film.

Several antisolvents with different miscibility to the host solvent (Dimethylformamide and Dimethyl sulfoxide) were chosen as the candidates. For PL analysis, peak intensity, peak position and peak full width at half maximum were tracked and analyzed. Diethyl ether (DE) showed better results with the highest peak intensity and slowest intensity increase rate.  

In-situ transmittance analysis was also performed for the antisolvent stage as well as the thermal annealing stage using a pre-drilled hot plate kept at 100 °C. Transmittance at 480 nm and 750 nm were picked to track the evolution for antisolvent and annealing stages, respectively. Similarly, DE shows the slowest decay leading to uniform, dense film later confirmed by scanning electron microscope analysis.

Utilizing the results above, we applied a DE antisolvent treatment for slot die coated perovskite films. Devices were made from ITO substrate, SnO2 (slot die coating), MAPbI3 (slot die coating), Spiro-MeOTAD (spin coating) and gold (thermal evaporation). All coating procedures were carried out in ambient conditions. Champion device showed 18.57% efficiency with 23.48 mA/cm2 short circuit current density, 1.06 V open circuit voltage and 0.75 fill factor. The antisolvent bath treatment proved successful for depositing large area high quality perovskite films. Coupled with in-situ analysis, it enables the precise pinpoint and manipulation of the processing window after the film deposition, which will be a huge benefit for industrial operations.

This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) grant: EP/V010913/1

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