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1. Manganese-Doped One-Dimensional Organic Lead Bromide Perovskites with Bright White Emissions

   https://doi.org/10.1021/acsami.7b12456  

   Zhou, Chenkun ; Tian, Yu ; Khabou, Oussama ; Worku, Michael ; Zhou, Yan ; Hurley, Joseph ; Lin, Haoran ; Ma, Biwu ( November 2017 , ACS Applied Materials & Interfaces)
2. Photoluminescence detection of symmetry transformations in low-dimensional ferroelectric ABO 3 perovskites

   https://doi.org/10.1039/D0TC01183E  

   Ofoegbuna, Tochukwu ; Bajgiran, Khashayar R. ; Kizilkaya, Orhan ; Thomson, Stuart A. ; Melvin, Adam T. ; Dorman, James A. ( August 2020 , Journal of Materials Chemistry C)

   null (Ed.)

   Symmetry-dependent properties such as ferroelectricity are suppressed at room temperature in Pb-free ABO 3 perovskites due to antiferrodistortive dynamics (octahedral rotations/tilts), resulting in the preferential stabilization of centrosymmetric crystals. For this reason, defect engineering (Ca doping, oxygen vacancy, etc. ) has been leveraged to break the symmetry of these crystals by inducing symmetry/structural transitions to modify the local A/B-site environment. This work demonstrates the use of in situ / ex situ photoluminescence spectroscopy to systematically detect symmetry/structural transformations in prototypical ferroelectric ABO 3 perovskites. These baseline optical responses are compared to recently synthesized Ca x Sr 1−x NbO 3 (CSNO) nanocrystals, which undergoes similar ferroelectric/structural phase transitions. Furthermore, the resultant PL response is corroborated with X-ray diffraction (XRD) and absorption spectroscopy (XAS) measurements to confirm the structural changes. This ability to directly monitor the local site symmetry within ABO 3 perovskites via photoluminescence spectroscopy can be used to screen for temperature- and defect-induced ferroelectric transitions. 

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3. Two-dimensional halide perovskites featuring semiconducting organic building blocks

   https://doi.org/10.1039/d0qm00233j  

   Gao, Yao ; Wei, Zitang ; Hsu, Sheng-Ning ; Boudouris, Bryan W. ; Dou, Letian ( January 2020 , Materials Chemistry Frontiers)

   Two-dimensional (2D) organic–inorganic hybrid halide perovskites exhibit unique properties, such as long charge carrier lifetimes, high photoluminescence quantum efficiencies, and great tolerance to defects. Over the last several decades tremendous progress has occurred in the development of 2D layered halide perovskite semiconductor materials and devices. Chemical functionalization of 2D halide perovskites is an effective approach for tuning their electronic properties. A large amount of effort has been made in compositional engineering of the cations and anions in the perovskite lattice. However, few efforts have incorporated rationally designed semiconducting organic moieties into these systems to alter the overall chemical and optoelectronic properties of 2D perovskites. In fact, incorporation of large conjugated organic groups in the spatially confined inorganic perovskite matrix was found to be challenging, and this synthetic challenge hinders a deeper understanding of the materials’ structure–property relationships. Recently, exciting progress has been made regarding the molecular design, optical characterization, and device fabrication of novel 2D halide perovskite materials that incorporate functional organic semiconducting building blocks. In this article, we provide a timely review regarding this recent progress. Moreover, we discuss successes and current challenges regarding the synthesis, characterization, and device applications of such hybrid materials and provide a perspective on the true future promise of these advanced nanomaterials. 

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4. Perovskite grain wrapping by converting interfaces and grain boundaries into robust and water-insoluble low-dimensional perovskites

   https://doi.org/10.1126/sciadv.abq4524  

   Jiao, Haoyang ; Ni, Zhenyi ; Shi, Zhifang ; Fei, Chengbin ; Liu, Ye ; Dai, Xuezeng ; Huang, Jinsong ( December 2022 , Science Advances)

   Stabilizing perovskite solar cells requires consideration of all defective sites in the devices. Substantial efforts have been devoted to interfaces, while stabilization of grain boundaries received less attention. Here, we report on a molecule tributyl(methyl)phosphonium iodide (TPI), which can convert perovskite into a wide bandgap one-dimensional (1D) perovskite that is mechanically robust and water insoluble. Mixing TPI with perovskite precursor results in a wrapping of perovskite grains with both grain surfaces and grain boundaries converted into several nanometer-thick 1D perovskites during the grain formation process as observed by direct mapping. The grain wrapping passivates the grain boundaries, enhances their resistance to moisture, and reduces the iodine released during light soaking. The perovskite films with wrapped grains are more stable under heat and light. The best device with wrapped grains maintained 92.2% of its highest efficiency after light soaking under 1-sun illumination for 1900 hours at 55°C open-circuit condition.

    

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5. Minimal Molecular Building Blocks for Screening in Quasi-Two-Dimensional Organic–Inorganic Lead Halide Perovskites

   https://doi.org/10.1021/acs.nanolett.3c00082  

   McArthur, Jack ; Filip, Marina R. ; Qiu, Diana Y. ( April 2023 , Nano Letters)