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Inverted perovskite solar cells passivated via organic cations exhibit superior power conversion efficiency compared to un-passivated ones. These record efficiencies have been reached thanks to the use of large organic cations to passivate the interface between the perovskite absorber and the transport layers. Here, we study the optoelectronic properties and chemical structure of interface doped perovskite solar cells where large cations, namely Cl-PEAI and F-PEAI, were incorporated at both front and rear interfaces of the absorber. The effect of the cation addition led to an increase of all the main PV characteristic, reaching PCE values up to 23.7%. We combined steady-state and time-resolved multidimensional photoluminescence imaging techniques to probe the main optoelectronic and transport properties of such devices. We thus obtained quantitative maps for physical parameters such as Quasi Fermi Level Splitting (QFLS), Urbach Energy and surface recombination rate, which proved a homogenous passivation by Cl-PEAI and F-PEAI cations over the 3D surface. For instance, the front and rear surface recombination velocities are reduced by a factor of 6 to 8 for Cl-PEAI based samples and 5 to 10 for F-PEAI based samples. In addition, we identified interfacial passivation as the main mechanism leading to a clear improvement of the Voc which increases from 1.10 to 1.16 eV. Indeed, we noticed a clear increase in terms of QFLS only after the addition of the electron transport layer whereas only an increase in the range of 0.01-0.02 eV was observed for bare perovskite thin film with the cation on top. Mapping the opto-electronical properties showed their good spatial homogeneity, By linking optical and electrical measurements we highlight the benefits of this passivation method in maximising all the main photovoltaic characteristics and in approaching inverted perovskite solar cell theoretical limit.
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