Alanazi, Anwar Qasem MKubicki, Dominik JózefProchowicz, DanielAlharbi, Essa Awadh RBouduban, Marine Eva FedoraJahanbakhshi, FarzanehMladenović, MarkoMilić, Jovana V.Giordano, FabrizioRen, DanAlyamani, Ahmed Y.Albrithen, HamadAlbadri, AbdulrahmanAlotaibi, Mohammad HayalMoser, Jacques-EdouardZakeeruddin, Shaik MohammedRöthlisberger, UrsulaEmsley, LyndonGraetzel, Michael2019-11-122019-11-122019-11-122019-10-0810.1021/jacs.9b07381https://infoscience.epfl.ch/handle/20.500.14299/162890Chemical doping of inorganic–organic hybrid perovskites is an effective way of improving the performance and operational stability of perovskite solar cells (PSCs). Here we use 5-ammonium valeric acid iodide (AVAI) to chemically stabilize the structure of α-FAPbI3. Using solid-state MAS NMR, we demonstrate the atomic-level interaction between the molecular modulator and the perovskite lattice and propose a structural model of the stabilized three-dimensional structure, further aided by density functional theory (DFT) calculations. We find that one-step deposition of the perovskite in the presence of AVAI produces highly crystalline films with large, micrometer-sized grains and enhanced charge-carrier lifetimes, as probed by transient absorption spectroscopy. As a result, we achieve greatly enhanced solar cell performance for the optimized AVA-based devices with a maximum power conversion efficiency (PCE) of 18.94%. The devices retain 90% of the initial efficiency after 300 h under continuous white light illumination and maximum-power point-tracking measurement.Lead halide perovskitePerovskite solar cellsSolid state NMRAtomic level microstructureAmmonium valeric acid iodidetext::journal::journal article::research article