Bimolecularly-Passivated Interface Enables Efficient and Stable Inverted Perovskite Solar Cells

Compared to the n-i-p structure, inverted (p-i-n) perovskite solar cells (PSCs) promise increased operating stability; however, to date, these photovoltaic cells suffer lower power conversion efficiencies (PCEs), the result of nonradiative recombination losses, particularly at the perovskite/C₆₀ interface. Here we hypothesize that implementing the two functions is highly needed at the interface – 1) passivation of surface defects; and 2) the reflecting of minority carriers away from the interface and back into the bulk. We incorporate one molecule to passivate surface defects and suppress recombination via chemical interactions with perovskite. The other molecule was employed to repel minority carriers and reduce contact-induced interface recombination, achieved through field-effect passivation. The approach leads to a 5-fold increase in carrier lifetime and a 3-fold reduction in photoluminescence quantum yield (PLQY) loss, enabling the first certified quasi-steady-state PCE over 25% for inverted PSCs with stable operation at 65°C for over 2,000 hours in ambient air. We produce monolithic all-perovskite tandem solar cells with 28.1% PCE.