Overcoming photovoltage deficit via natural amino acid passivation for efficient perovskite solar cells and modules

Abstract

Electronic defects at grain boundaries and surfaces of perovskite crystals impair the photovoltaic performance and stability of solar devices. In this work, we report the compensation of photovoltage losses in blade-coated methylammonium lead triiodide (MAPbI₃) devices via passivation with natural amino acid (NAA) molecules. We found that the optoelectronic properties of NAA-passivated perovskite films and the corresponding device performances are closely correlated with the molecular interaction strength. A side-by-side comparative study of four typical NAAs reveals that arginine (Arg) functionalized with a guanidine end group exhibits optimum passivation effects owing to the strongest coordinative bonding with the uncoordinated Pb²⁺, which markedly suppresses the detrimental antisite Pb_I deep level defects. As a result, nonradiative charge recombination is significantly reduced, resulting in a substantially increased open-circuit voltage (V_OC) of 1.17 V and a high efficiency of 20.49%. A solar module with an active area of 10.08 cm² is also fabricated, yielding an efficiency of 15.65% with negligible V_OC losses. In parallel, the Arg-passivated solar devices exhibit enhanced operational stability due to the formation of a hydrophilic Arg protective layer which encapsulates the perovskite crystals.