Multidentate chelation defect passivation via hyperbranched polysiloxane for efficient and stable inverted perovskite solar cells

Polymer additives with diverse functional groups and excellent stability offer distinct advantages in passivating perovskite defects to boost the efficiency of perovskite solar cells (PSCs). However, conventional linear polymers commonly used exhibit a restricted capacity for passivation, which hinders further improvement of device performance. Here, we propose a multidentate chelation defect passivation strategy by introducing a polysiloxane with maleic acid structure (HPSiM) into the perovskite active layer as bulk additives. The HPSiM polymer features a hyperbranched architecture where each branch chain is rich in electron-donor functional groups, enabling a broader spectrum of activity and stronger chelation, ultimately facilitating multidentate chelation with Pb²⁺ ions. The interaction of HPSiM with perovskite crystals delays nucleation and crystal growth, facilitating the creation of high-quality perovskite films while reducing non-radiative recombination, ultimately improving both device efficiency and stability. Consequently, the efficiency of HPSiM-modified PSCs achieves 25.38 %, retaining 91.6 % of its initial value following 1000 hours of aging under maximum power point tracking at 55°C. Our research presents a robust strategy aimed at the design of hyperbranched polymers endowed with multidentate chelating functionality, intending to enhance the performance of PSCs.