Revealing how ambient atmosphere affects the hole-selective self-assembled monolayers for efficient and stable perovskite solar cells

Self-assembled monolayers (SAMs) have been widely employed in high-performance inverted perovskite solar cells (PSCs) due to their excellent hole-selecting capabilities. However, most researchers suffer from the periodical non-reproducibility of the SAMs based PSCs even in a nitrogen filled glovebox for the complex and changing chemical atmosphere. But rare researches reveal how the ambient vapors affect the SAMs for efficient PSCs. In this work, we systematically investigated how varied vapors in a lab atmosphere affect the SAMs, exhibiting that most common vapors such as water, acetone or isopropanol do not hinder the SAMs performing in PSCs, except volatile acids or bases. Moreover, the dimethyl sulfoxide (DMSO) vapor is found to be able to dissociate the SAM micelles and form a dense SAM layer on substrates, due to the strong bonding between DMSO and the methoxy groups of SAMs. The DMSO vapor modified SAMs lead to more compact buried interface and notably suppressed charge recombination, which increases the efficiency of PSCs from 24.17% to 25.18%, compared to SAMs fabricated in N2. The DMSO modified SAMs based device also shows enhanced operation stability under one-sun illumination, maintaining 90% of the initial efficiency after 800 h of maximum power point tracking.