Browsing by Author "Correa-Baena, Juan-Pablo"

Now showing 1 - 2 of 2

Effects of Alkaline Earth Metal Additives on Methylammonium-Free Lead Halide Perovskite Thin Films and Solar Cells
(Wiley-v C H verlag Gmbh, 2022) Yuce, Hurriyet; LaFollette, Diana K.; Demir, Mustafa M.; Perini, Carlo A. R.; Correa-Baena, Juan-Pablo
Organic-inorganic lead halide perovskite solar cells are regarded as one of the most promising technologies for the next generation of photovoltaics due to their high power conversion efficiency (PCE) and simple solution manufacturing. Among the different compositions, the formamidinium lead iodide (FAPbI(3)) photoactive phase has a bandgap of 1.4 eV, which enables the corresponding higher PCEs according to the Shockley-Queisser limit. However, the photoactive crystal phase of FAPbI(3) is not stable at room temperature. The most high-performing compositions to date have reduced this problem by incorporating the methylammonium (MA) cation into the FAPbI(3) composition, although MA has poor stability at high temperatures and in humid environments, which can limit the lifetime of FA(x)MA(1-x)PbI(3) films. Cs(x)FA(1-x)PbI(3) perovskites are also explored, but despite better stability they still lag in performance. Herein, the additive engineering of MA-free organic-inorganic lead halide perovskites using divalent cations Sr2+ and Ca2+ to enhance the performances of Cs(x)FA(1-x)PbI(3) perovskite compositions is explored. It is revealed that the addition of up to 0.5% of Sr2+ and Ca2+ leads to improvements in morphology and reduction in microstrain. The structural improvements observed correlate with improved solar cell performances at low additive concentrations.
Understanding the impact of SrI₂ additive on the properties of Sn-based halide perovskites
(Elsevier, 2022) Yuce, Hurriyet; Perini, Carlo A. R.; Hidalgo, Juanita; Castro-Mendez, Andres-Felipe; Evans, Caria; Franco Betancur, Pablo; Correa-Baena, Juan-Pablo
Organic-inorganic halide perovskites have been identified as favorable candidates for the next generation of photovoltaics. Adding alkali metal halides to perovskite films has been shown to be a viable option to improve the pemvskite film quality and to modulate their fundamental properties. In this work, we perform optical and electron-beam based characterizations of mixed Sn/Pb based perovskite films to investigate the effect of the addition of the alkaline metal halide SrI2. By analyzing structural (X-ray diffraction), morphological (Scanning Electron Microscopy), optical (photoluminescence), and chemical properties (X-ray photoelectron spectroscopy), we show a complex interplay of effects upon addition of Sr2+ into the perovskite solution. Low concentrations of Sr2+ increases lattice strain, which hints at incorporation of the additive into the perovskite lattice and improves the film optoelectronic properties. As the additive concentration increases beyond 0.5 mol %, microstrain decreases. At concentrations >0.5 mol %, Sr(2+ )induces significant reduction of the average domain size, which impacts both structural and optical properties of the perovskite film.