Researchers from the Emerging Electronic Technologies Group of Prof. Yana Vaynzof at Germany's Technische Universität Dresden have found that fundamental processes that occur during perovskite film formation strongly influence the reproducibility of the photovoltaic devices.

When depositing the perovskite layer from solution, an antisolvent is dripped onto the perovskite solution to trigger its crystallization. "We found that the duration for which the perovskite was exposed to the antisolvent had a dramatic impact on the final device performance, a variable which had, until now, gone unnoticed in the field." says Dr. Alexander Taylor, a postdoctoral research associate in the Vaynzof group and the first author on the study. "This is related to the fact that certain antisolvents may at least partly dissolve the precursors of the perovskite layer, thus altering its final composition. Additionally, the miscibility of antisolvents with the perovskite solution solvents influences their efficacy in triggering crystallization."

The results emphasize that as researchers fabricate their PV devices, differences in this antisolvent step could cause the often observed irreproducibility in performance. The authors went on to test a wide range of potential antisolvents, and showed that by controlling these phenomena, they could obtain cutting-edge performance from nearly every candidate tested.

"By identifying the key antisolvent characteristics that influence the quality of the perovskite active layers, we are also able to predict the optimal processing for new antisolvents, thus eliminating the need for the tedious trial-and-error optimization so common in the field." adds Dr. Fabian Paulus, leader of the Transport in Hybrid Materials Group at cfaed and a contributor to the study.

"Another important aspect of our study is the fact that we demonstrate how an optimal application of an antisolvent can significantly widen the processibility window of perovskite photovoltaic devices" notes Prof. Vaynzof, who led the work. "Our results offer the perovskite research community valuable insights necessary for the advancement of this promising technology into a commercial product."

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