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

Inverted inorganic CsPbI3 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 CsPbI3 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 CsPbI3 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 cm2 devices to deliver a record-high efficiency of 19.69%.