“Three-in-One” Self-Assembled Molecule Enables Inverted CsPbI 3 Solar Cells

Inverted inorganic CsPbI 3 perovskite solar cells (PSCs) hold great promise for stable and efficient tandem photovoltaics, yet their performance lags behind normal (n-i-p) counterparts due to limited film quality, inefficient carrier extraction, and severe defect-mediated recombination. Here, we demonstrate a triple-functional self-assembled molecule (SAM) engineering strategy to tackle these issues simultaneously. By directly incorporating the SAM into the CsPbI 3 precursor solution, the SAM spontaneously enriches at the buried interface to form an efficient hole-selective contact. Meanwhile, its strong interaction with perovskite accelerates crystallization kinetics and enables comprehensive passivation of defects at both grain boundaries and interfaces. As a result, inverted CsPbI 3 PSCs achieve an efficiency of 21.10% (certified 20.62%). By leveraging the “three-in-one” functionality of the SAM, this strategy endows PSCs with ideal operational stability (retaining 90% of initial efficiency after 680 h of continuous operating at ∼50 °C) and enables 1 cm 2 devices to deliver a record-high efficiency of 19.69%.