Quasi-two-dimensional halide perovskites are commonly used in solar cells, as they are more stable than their three-dimensional analogues. Nevertheless, it is still challenging to meet the stability ...requirements under high-humidity conditions. Here, we design π-conjugated carbazole (CA) cations to increase the water resistance of perovskite. We control the crystallization kinetics by the anti-solvent strategy to locate the hydrophobic low-⟨n⟩-value phase on the surface of the perovskite film. The resulting CA2MA4Pb5I16 film does not decompose after being immersed in water for several minutes. We further regulate the vertical orientation of perovskite crystals by introducing NH4SCN additive, resulting in improved carrier transport dynamics. As a result, the optimized CA2MA4Pb5I16 device achieves a notable power conversion efficiency (PCE) of 18.23% and retains more than 85% of the original PCE after 2000 h under a relative humidity of 65% at 25 °C. This is one of the most stable reported unencapsulated perovskite solar cells in high-humidity environments.
The power conversion efficiency of the formamidinium tin iodide (FASI) solar cells constantly increases, with the current record power conversion efficiency approaching 15%. The literature reports a ...broad anomaly distribution of the photoluminescence (PL) peak position. The PL anomaly is particularly relevant to photovoltaic applications since it directly links the material's bandgap and subgap defects energy, which are crucial to extracting its full photovoltaic potential. Herein, the PL of FASI polycrystalline thin film and powder is studied. It is found that a distribution of PL peak positions in line with the distribution available in the literature systematically. The distribution in PL is linked to the octahedral tilting and Sn off‐centering within the perovskite lattice, influenced by the procedure used to prepare the material. Our finding paves the way toward controlling the energy distribution of tin perovskite and thus preparing highly efficient tin halide perovskite solar cells.
The photoluminescence peak energy of polycrystalline formamidinium tin iodide perovskites is strongly dependent on the synthetic protocol, ageing, and oxidative stress, showing a broad distribution over more than 50 nm and slow dynamic behavior. Herein, the different sources of variation are identified and analyzed by comparing solid state synthesized powder to thin films.
Die Kristallisation von Perowskiten auf Zinnbasis wird durch das Fluorid in SnF2 verbessert. Das Anion dieses typischen Additivs ist für eine homogenere Keimbildung bei der Bildung von ...Perowskit‐Dünnschichten im Lösungsprozess verantwortlich. Darüber hinaus komplexiert Fluorid selektiv SnIV und verhindert dessen Einbau in die Perowskitstruktur, wie Jorge Pascual, Antonio Abate et al. in ihrem Forschungsartikel auf S. 21753 berichten.
Tin perovskites are the most promising environmentally friendly alternative to lead perovskites. Among tin perovskites, FASnI3 (CH4N2SnI3) shows optimum band gap, and easy processability. However, ...the performance of FASnI3 based solar cells is incomparable to lead perovskites for several reasons, including energy band mismatch between the perovskite absorber film and the charge transporting layers (CTLs) for both types of carriers, i.e., for electrons (ETLs) and holes (HTLs). However, the band diagrams in the literature are inconsistent, and the charge extraction dynamics are poorly understood. In this paper, we study the energy band positions of FASnI3 based perovskites using Kelvin probe (KP) and photoelectron yield spectroscopy (PYS) to provide a precise band diagram of the most used device stack. In addition, we analyze the defects within the current energetic landscape of tin perovskites. We uncover the role of bathocuproine (BCP) in enhancing the electron extraction at the fullerene C60/BCP interface. Furthermore, we used transient surface photovoltage (tr-SPV) for the first time for tin perovskites to understand the charge extraction dynamics of the most reported HTLs such as NiOx and PEDOT, and ETLs such as C60, ICBA, and PCBM. Finally, we used Hall effect, KP, and time-resolved photoluminescence (TRPL) to estimate an accurate value of the p-doping concentration in FASnI3 and showed a consistent result of 1.5 * 1017 cm-3. Our findings prove that the energetic system of tin halide perovskites is deformed and should be redesigned independently from lead perovskites to unlock the full potential of tin perovskites.
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