Flash infrared annealing method: the pulse time to control the perovskite crystal nucleation and growth from solution
Sandy Sanchez a
a École Polytechnique Fédérale de Lausanne EPFL, CH
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Oral, Sandy Sanchez, presentation 075
Publication date: 11th February 2019

This works unveils how to produce defect-free and compact perovskite films by using the Flash Infrared Annealing (FIRA) method, describing the kinetic processes involved. It addresses how FIRA induces crystallization in perovskite films.1, 2 This includes the nucleation of crystals followed by their growth and the kinetics of the crystal growth from solution as a function of the pulsed time. FIRA is a cost-effective fast synthesis process, which provides control over the final morphology of the perovskite thin film. The FIRA setup has been employed to synthesize highly crystalline organic-inorganic perovskite films and transparent inorganic conductive layers, and adding it to the manufacturing process helps to overcome the perovskite stability challenge.

To make FIRA effective is necessary to understand the physicochemical phenomena that take place during the crystallization of the synthesized film. Is important, for example, to know the pathways of the nucleation and crystal growth through intermediate phases. In FIRA the crystallization occurs by it intermediate phases until the final crystal phase as it happens on the antisolvent method and posterior thermal low temperature annealing. The difference consists in the fastness on the process, which in FIRA is on the order of milliseconds and in AS is on the order of seconds.  As the solvent evaporates, the chemical potential of the solution changes, eventually reaching supersaturation, allowing the formation of a new phase by crystal growth.  Once the supersaturation is reached nucleation clusters appear, followed by the growth these crystals.

 

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