Quantitative Surface Passivation Through Drop‐on‐Demand Inkjet Printing Enables Highly Efficient Perovskite Solar Cells

Abstract Deposition of a passivation layer on top of the perovskite is proven to be an effective method for improving the efficiency and long‐term stability of perovskite solar cells (PSCs). And the spin‐coating method is the most typical and popular method developed for this purpose. However, the spin‐coating method wastes substantial passivator materials, thus the quantitative relationship between the passivator amount and the device performance cannot be obtained. Herein, a quantitative deposition method is developed through drop‐on‐demand inkjet printing to investigate the influence of 2‐adamantylamine hydrochloride (2‐ADAHCl) deposition surface density on the device performance, which is found to have a significant impact on the device performance. A low deposition surface density of 1.1 µg cm −2 does not reach its optimum passivation capability. In contrast, an excess deposition surface density of 10.1 µg cm −2 would lead to energy level mismatch and large series resistance at the perovskite/hole transport layer (HTL) interface, thus resulting in inferior device properties. At an optimum deposition surface density of 2.5 µg cm −2 , perovskite surface defects are greatly suppressed, and the interfacial contact between perovskite and HTL is improved. Finally, PSCs with a high efficiency of 24.57% are achieved with improved operational and environmental stabilities.