Dopamine Dopes the Performance of Perovskite Solar Cells

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.