The electron transport layer (ETL) is a crucial component of perovskite solar cells (PSCs) as it greatly influences their photovoltaic performance. Among various currently used ETL materials, SnO₂ stands out due to its unique advantages, including low‐temperature fabrication and rapid electron extraction capability and excellent energy match of its conduction band edge with that of the commonly used perovskite formulations. However, the currently employed SnO₂ layers contain surface defects, such as hydroxyl groups and oxygen vacancies that impair the desired growth of highly crystalline and defect less perovskite films during solution processing of n‐i‐p type PSCs reducing their power conversion efficiency (PCE) and stability. Here, a self‐assembled monolayer (SAM) is introduced of dopamine hydrochloride (DACl) on the SnO2 film, whose catechol moiety adheres strongly to the SnO2 surface, while its methylammonium groups template the growth of the perovskite layer. Introducing the dopamine SAM at the interface between the ETL and the perovskite increases substantially the solar‐to‐electric PCE while greatly enhancing the PSC stability. This findings demonstrate the surprising benefits of this well‐known neurotransmitter for the photovoltaic performance of PSCs which this is rationalized here by DFT and ab initio molecular dynamics calculations.