Perovskite

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Erik M J Johansson - One of the best experts on this subject based on the ideXlab platform.

Jinsong Huang - One of the best experts on this subject based on the ideXlab platform.

  • Blading Phase-Pure Formamidinium-Alloyed Perovskites for High-Efficiency Solar Cells with Low Photovoltage Deficit and Improved Stability.
    Advanced materials (Deerfield Beach Fla.), 2020
    Co-Authors: Peter N. Rudd, Zhibin Yang, Qi Wang, Jinsong Huang
    Abstract:

    Currently, blade-coated Perovskite solar cells (PSCs) with high power conversion efficiencies (PCEs), that is, greater than 20%, normally employ methylammonium lead tri-iodide with a sub-optimal bandgap. Alloyed Perovskites with formamidinium (FA) cation have narrower bandgap and thus enhance device photocurrent. However, FA-alloyed Perovskites show low phase stability and high moisture sensitivity. Here, it is reported that incorporating 0.83 molar percent organic halide salts (OHs) into Perovskite inks enables phase-pure, highly crystalline FA-alloyed Perovskites with extraordinary optoelectronic properties. The OH molecules modulate the crystal growth, enhance the phase stability, passivate ionic defects at the surface and/or grain boundaries, and enhance the moisture stability of the Perovskite film. A high efficiency of 22.0% under 1 sun illumination for blade-coated PSCs is demonstrated with an open-circuit voltage of 1.18 V, corresponding to a very small voltage deficit of 0.33 V, and significantly improved operational stability with 96% of the initial efficiency retained under one sun illumination for 500 h.

  • enhanced thermal stability in Perovskite solar cells by assembling 2d 3d stacking structures
    Journal of Physical Chemistry Letters, 2018
    Co-Authors: Yanjun Fang, Jinsong Huang, Jingjing Zhao, Zhaolai Chen, Shuang Yang, Xiaopeng Zheng, Shi Tang
    Abstract:

    Two-dimensional (2D) Perovskites have been shown to be more stable than their three-dimensional (3D) counterparts due to the protection of the organic ligands. Herein a method is introduced to form 2D/3D stacking structures by the reaction of 3D Perovskite with n-Butylamine (BA). Different from regular treatment with n-Butylammonium iodide (BAI) where 2D Perovskite with various layers form, the reaction of BA with MAPbI3 only produce (BA)2PbI4, which has better protection due to more organic ligands in (BA)2PbI4 than the mixture of 2D Perovskites. Compared to BAI treatment, BA treatment results in smoother 2D Perovskite layer on 3D Perovskites with a better coverage. The photovoltaic devices with 2D/3D stacking structures show much improved stability in comparison to their 3D counterparts when subjected to heat stress tests. Moreover, the conversion of defective surface into 2D layers also induces passivation of the 3D Perovskites resulting in an enhanced efficiency.

  • organometal trihalide Perovskite single crystals a next wave of materials for 25 efficiency photovoltaics and applications beyond
    Journal of Physical Chemistry Letters, 2015
    Co-Authors: Jinsong Huang, Yuchuan Shao, Qingfeng Dong
    Abstract:

    Hybrid Perovskite single crystals have been recently revealed to have superior optoelectronic properties to Perovskite polycrystalline thin films, especially the extraordinarily long carrier diffusion length due to the eliminated grain boundaries. One question that naturally arises is whether the single crystal hybrid Perovskites can be a next wave of photoactive materials for even higher-efficiency devices. This Perspective presents an overview of the historic evolution in understanding of carrier diffusion length in CH3NH3PbI3, the initial investigations of the synthesis of single crystalline hybrid Perovskites, and the characterization of their optoelectronic properties. Our analysis indicates that single crystalline Perovskite materials have potential to further boost photovoltaic device power conversion efficiency to 25%. The potential opportunities for the fundamental study of the Perovskite intrinsic properties, particularly the carrier mobility and carrier recombination lifetime, and other fields ...

Mercouri G Kanatzidis - One of the best experts on this subject based on the ideXlab platform.

  • two dimensional hybrid halide Perovskites principles and promises
    Journal of the American Chemical Society, 2019
    Co-Authors: Lingling Mao, Constantinos Stoumpos, Mercouri G Kanatzidis
    Abstract:

    Hybrid halide Perovskites have become the “next big thing” in emerging semiconductor materials, as the past decade witnessed their successful application in high-performance photovoltaics. This resurgence has encompassed enormous and widespread development of the three-dimensional (3D) Perovskites, spearheaded by CH3NH3PbI3. The next generation of halide Perovskites, however, is characterized by reduced dimensionality Perovskites, emphasizing the two-dimensional (2D) Perovskite derivatives which expand the field into a more diverse subgroup of semiconducting hybrids that possesses even higher tunability and excellent photophysical properties. In this Perspective, we begin with a historical flashback to early reports before the “Perovskite fever”, and we follow this original work to its fruition in the present day, where 2D halide Perovskites are in the spotlight of current research, offering characteristics desirable in high-performance optoelectronics. We approach the evolution of 2D halide Perovskites f...

  • unraveling the chemical nature of the 3d hollow hybrid halide Perovskites
    Journal of the American Chemical Society, 2018
    Co-Authors: Ioannis Spanopoulos, Constantinos Stoumpos, Ram Seshadri, Weijun Ke, Emily C Schueller, Oleg Y Kontsevoi, Mercouri G Kanatzidis
    Abstract:

    The newly introduced class of 3D halide Perovskites, termed “hollow” Perovskites, has been recently demonstrated as light absorbing semiconductor materials for fabricating lead-free Perovskite solar cells with enhanced efficiency and superior stability. Hollow Perovskites derive from three-dimensional (3D) AMX3 Perovskites (A = methylammonium (MA), formamidinium (FA); M = Sn, Pb; X = Cl, Br, I), where small molecules such as ethylenediammonium cations (en) can be incorporated as the dication without altering the structure dimensionality. We present in this work the inherent structural properties of the hollow Perovskites and expand this class of materials to the Pb-based analogues. Through a combination of physical and spectroscopic methods (XRD, gas pycnometry, 1H NMR, TGA, SEM/EDX), we have assigned the general formula (A)1–x(en)x(M)1–0.7x(X)3–0.4x to the hollow Perovskites. The incorporation of en in the 3D Perovskite structure leads to massive M and X vacancies in the 3D [MX3] framework, thus the term...

  • structure band gap relationships in hexagonal polytypes and low dimensional structures of hybrid tin iodide Perovskites
    Inorganic Chemistry, 2017
    Co-Authors: Constantinos Stoumpos, Lingling Mao, Christos D Malliakas, Mercouri G Kanatzidis
    Abstract:

    The present study deals with the structural characterization and classification of the novel compounds 1–8 into Perovskite subclasses and proceeds in extracting the structure–band gap relationships between them. The compounds were obtained from the employment of small, 3–5-atom-wide organic ammonium ions seeking to discover new Perovskite-like compounds. The compounds reported here adopt unique or rare structure types akin to the prototype structure Perovskite. When trimethylammonium (TMA) was employed, we obtained TMASnI3 (1), which is our reference compound for a “perovskitoid” structure of face-sharing octahedra. The compounds EASnI3 (2b), GASnI3 (3a), ACASnI3 (4), and IMSnI3 (5) obtained from the use of ethylammonium (EA), guanidinium (GA), acetamidinium (ACA), and imidazolium (IM) cations, respectively, represent the first entries of the so-called “hexagonal Perovskite polytypes” in the hybrid halide Perovskite library. The hexagonal Perovskites define a new family of hybrid halide Perovskites with a...

Martin Stolterfoht - One of the best experts on this subject based on the ideXlab platform.

  • comparing the excited state properties of a mixed cation mixed halide Perovskite to methylammonium lead iodide
    Journal of Chemical Physics, 2020
    Co-Authors: Jan C Brauer, Demetra Tsokkou, Sandy Sanchez, Nikolaos Droseros, Bart Roose, Edoardo Mosconi, Xiao Hua, Martin Stolterfoht
    Abstract:

    Organic–inorganic Perovskites are one of the most promising photovoltaic materials for the design of next generation solar cells. The lead-based Perovskite prepared with methylammonium and iodide was the first in demonstrating high power conversion efficiency, and it remains one of the most used materials today. However, Perovskites prepared by mixing several halides and several cations systematically yield higher efficiencies than “pure” methylammonium lead iodide (MAPbI3) devices. In this work, we unravel the excited-state properties of a mixed-halide (iodide and bromide) and mixed-cation (methylammonium and formamidinium) Perovskite. Combining time-resolved photoluminescence, transient absorption, and optical-pump–terahertz-probe experiments with density functional theory calculations, we show that the population of higher-lying excited states in the mixed material increases the lifetime of photogenerated charge carriers upon well above-bandgap excitation. We suggest that alloying different halides and different cations reduces the structural symmetry of the Perovskite, which partly releases the selection rules to populate the higher-energy states upon light absorption. Our investigation thus shows that mixed halide Perovskites should be considered as an electronically different material than MAPbI3, paving the way toward further materials optimization and improved power conversion efficiency of Perovskite solar cells.

Lioz Etgar - One of the best experts on this subject based on the ideXlab platform.