(Invited) Controlling Solution Chemistry from Lab-Scale Spin Coating to Scalable Deposition for High-Performance Perovskite Solar Cells

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Organic-Inorganic hybrid halide perovskites have recently emerged as a new class of light absorbers that have demonstrated a rapid progress and impressive efficiencies (>22%) for solar conversion applications. Despite the rapid progress demonstrated by these light absorbers, there is still a lack of understanding of some fundamental material/physical/chemical properties of these materials. There is also a significant processing gap between the lab-scale spin coating and scalable deposition methods toward future roll-to-roll manufacturing. The challenge results from the sensitivity of perovskite crystallization and film formation to the processing conditions, which depend strongly on the specific deposition method. In this presentation, I will present our recent studies toward a better understanding and control of perovskite nucleation, grain growth, and microstructure evolution using solution processing. The precursor chemistry and growth conditions are found to affect significantly the structural and electro-optical properties of perovskite thin films. We also find that the precursor ink chemistry (solvent, coordination chemistry) of perovskite is critical for scalable deposition; but this has largely been underexplored. We present a rational design of perovskite precursor film formation to achieve highly specular films using scalable deposition methods. Using these high quality perovskite films, we have achieved device efficiencies approaching the values obtained on small scale by spin coating. These findings make a significant advance towards commercialization of the perovskite photovoltaic technology. These results and others will be discussed.