Researchers at HZB, University of Potsdam, Technical University Berlin and Empa have developed a graphene oxide (GO) /self-assembled monolayer (SAM) bilayer hole-transport architecture that addresses key efficiency and stability bottlenecks in tin-lead (Sn–Pb) perovskite solar cells and enables high-performance all-perovskite triple-junction devices. All-perovskite multi-junction solar cells (APMSCs) are attractive due to their high theoretical efficiencies - approximately 44% for double-junction and 52% for triple-junction configurations. Recent progress has relied heavily on narrow-band-gap (~1.25 eV) Sn-Pb perovskite bottom cells. However, their performance has remained constrained by the widely used hole transport layer PEDOT:PSS, which introduces both optical and chemical losses. Its parasitic absorption (typically from 30-50 nm thick layers) reduces current density by 0.5-1.4 mA cm −2 , while its acidic and hygroscopic nature accelerates degradation through interfacial reactions that promote iodine vacancy formation and oxidation of I − and Sn 2+ .
GO/SAM bilayer boosts efficiency of Sn-Pb perovskite triple-junction solar cells
