ITO Nanoparticles to Stabilize the Self‐Assembly of Hole Transport Layer in Inverted Perovskite Solar Cells

Recently, inverted perovskite solar cells (PSCs) show rapidly improved efficiency with the use of self-assembled molecules (SAM). However, device stability remains a challenge due to the easy desorption of the SAM molecule. Here, functionalized indium tin oxide nanoparticles (INPs) are introduced to promote and reinforce the self-assembly of SAM on the substrate. INPs contain abundant ─OH groups to uniformly anchor SAM molecules. Importantly, different from traditional physically absorbed and easy-desorbed ─OH in ITO substrate, the ─OH groups on INPs are stably bonded, resistant to solvent rinsing and long-term aging, thus inhibiting SAM desorption during device aging. As a result, PSCs with INPs exhibit high efficiency of 26.44% with good operational stability under ISOS-L-2 protocol, retaining ∼≈91% of initial efficiency after maximum power point (MPP) tracking with continuous illumination at 85 °C.