Investigation of Fe2+-incorporating organic–inorganic hybrid perovskites from first principles and experiments
TL;DR: In this article, the structural, electronic, magnetic and optical properties of perovskite CH3NH3(Pb:Fe)I3 were investigated, and the effect of iron (Fe) metal ion ion doping on the properties of the perovsites and solar cell performance was investigated.
Abstract: The development of high efficiency perovskite solar cells (PSCs) has been proved to depend on the stability and optical properties of perovskite materials. A lot of efforts have been applied to improving these properties. Among them, the alternative mixed-metal perovskite composition has been considered as a new solution for photovoltaic device applications to satisfy the demand for exploring efficient photovoltaic performance. Here, we have systematically performed first-principles calculations using density-functional theory (DFT) to study the structural, electronic, magnetic and optical properties of the perovskite CH3NH3(Pb:Fe)I3, and investigated the effect of iron (Fe) metal ion doping on the properties of the perovskites and solar cell performance. The calculated results reveal that the perovskite CH3NH3(Pb:Fe)I3 exhibits half-metallic behavior due to the impurity bands induced by the Fe dopant crossing the Fermi level. Consequently, it is found that the absorption intensities of CH3NH3(Pb:Fe)I3 are slightly higher than those of CH3NH3PbI3 in the near-infrared light region. It is unexpected that the perovskite CH3NH3(Pb:Fe)I3 exhibits a large magnetic moment of 4 μB and its magnetic coupling belongs to the antiferromagnetic (AFM) configuration. Meanwhile, we found that the Fe incorporation can distort the structure due to its small ionic size, which significantly changes the device performance. Our findings provide a reference for exploring the properties of perovskite materials.
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TL;DR: A review on the capacity of metal ions to impart a broad range of effects from controlling crystallization to the alloying, doping, and passivation of perovskite materials is provided in this paper.
Abstract: The influence of metal ions on perovskite properties and resulting device performance has been undeniable in progressing the field of inorganic and organic–inorganic hybrid perovskites. Here we provide a review on the capacity of metal ions to impart a broad range of effects from controlling crystallization to the alloying, doping, and passivation of perovskite materials. Although some metal ions have already proved effective in modulating bandgaps through alloying, their ability to control crystallization, carrier concentration, and emissive effects still require significant improvements in fundamental understanding. This presents enormous opportunities in research that may afford novel properties and applications through unparalleled control of perovskite materials.
23 citations
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TL;DR: In this paper, the structural, electronic, and optical properties of pure and mixed perovskite systems were investigated by using density functional theory calculations, and the results reveal that three Pb-Sn-Ge perovsites are predicted to preserve improved structural stabilities over MAPbI3.
Abstract: In recent years, organic–inorganic hybrid halide perovskites have attracted great attention. In view of the toxicity of lead, lead-free perovskites have been developed in order to obtain comparable or better photovoltaic performance than MAPbI3. In this study, the structural, electronic, and optical properties of pure and mixed perovskite systems were investigated by using density functional theory calculations. The results reveal that three Pb–Sn–Ge perovskites are predicted to preserve improved structural stabilities over MAPbI3. The band gaps of hybrid perovskites can be tuned by means of Sn–Ge doping. The band gap of MAPb0.50Sn0.25Ge0.25I3 is in the optimum range of 1.3–1.4 eV. Optical property analysis implies that MAPb0.50Sn0.25Ge0.25I3 possesses a comparable absorption ability in the visible light region compared with the MAPbI3 structure. In addition, the results indicate that MAPb0.50Sn0.25Ge0.25I3 with the highest power conversion efficieny of 23.65% can be chosen as a potential candidate for th...
21 citations
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TL;DR: In this paper, lead-based hybrid perovskites have a major influence on their performance as photovoltaic (PV) light absorbers, while impurities in semiconductors could create harmful tra...
Abstract: Impurities in semiconductors, for example, lead-based hybrid perovskites, have a major influence on their performance as photovoltaic (PV) light absorbers. While impurities could create harmful tra...
17 citations
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TL;DR: This review presents the most characteristic perovskites that can be formed with the help of d-block metal ions with stable oxidation states, such as Ag+ or Ti4+, which have exhibited satisfactory photovoltaic properties until now.
Abstract: Pb2+ halide organic–inorganic perovskites are excellent semiconductors for use in solar energy applications, but at the expense of robustness and environmental compatibility. Tin (Sn), which sits just above lead in the periodic table, forms pure (or mixed with lead) perovskites when at the 2+ or 4+ oxidation state. It can act as a promising alternative; however, there are still some serious concerns regarding its suitability. This presents a major challenge; viable metal cations have to be identified. A good number of elements, originating from a large range of d-block metal ions, with adequate oxidation states, moderate toxicity, and relative abundance, seem ideal for this purpose. In this review, we present the most characteristic perovskites (conventional perovskites, layered, or double perovskites) that can be formed with the help of these metals. We focus on d-block metal ions with stable oxidation states, such as Ag+ or Ti4+, which have exhibited satisfactory photovoltaic properties until now. Further, we highlight the results involving compounds other than halide perovskites, such as oxides, chalcogenides, and nitrides (as well as oxyhalides, oxysulfides, and oxynitrides); a few of them are ferroelectric (based on Ti4+, Zr4+, Fe3+, and Cr3+) and can yield a photovoltage that exceeds the bandgap of the material. Finally, we present the critical challenges that currently limit the efficiency of these systems and propose prospects for future directions.
15 citations
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TL;DR: In this paper, the structural, electronic, and optical properties of mixed Pb-In halide perovskites based on the first-principles calculation using density functional theory were investigated.
Abstract: Hybrid halide perovskites have been supposed to be a versatile class of visible light absorbers because of their high absorption coefficient, long charge carrier lifetime, and diffusion length. However, little is known about their charge transport mechanism and analysis of microstructure. Herein, we systematically investigate the structural, electronic, and optical properties of the mixed Pb–In halide perovskites based on the first-principles calculation using density functional theory in detail. Furthermore, we verify that In ions play an important role in thin-film crystallization and quality. Our calculated results reveal that the mixed Pb–In halide perovskites exhibit excellent electronic properties because of the impurity bands induced by the In dopant, and the doped perovskite phase can be stabilized by Cl incorporation as revealed by the lower formation energy. More interestingly, it is unexpected that the peak intensities of mixed Pb–In halide perovskites are stronger in the UV region, and their a...
14 citations
References
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TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif
117,932 citations
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TL;DR: Two organolead halide perovskite nanocrystals were found to efficiently sensitize TiO(2) for visible-light conversion in photoelectrochemical cells, which exhibit strong band-gap absorptions as semiconductors.
Abstract: Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.
13,033 citations
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TL;DR: In this paper, a method for accurate and efficient local density functional calculations (LDF) on molecules is described and presented with results using fast convergent threedimensional numerical integrations to calculate the matrix elements occurring in the Ritz variation method.
Abstract: A method for accurate and efficient local density functional calculations (LDF) on molecules is described and presented with results The method, Dmol for short, uses fast convergent three‐dimensional numerical integrations to calculate the matrix elements occurring in the Ritz variation method The flexibility of the integration technique opens the way to use the most efficient variational basis sets A practical choice of numerical basis sets is shown with a built‐in capability to reach the LDF dissociation limit exactly Dmol includes also an efficient, exact approach for calculating the electrostatic potential Results on small molecules illustrate present accuracy and error properties of the method Computational effort for this method grows to leading order with the cube of the molecule size Except for the solution of an algebraic eigenvalue problem the method can be refined to quadratic growth for large molecules
8,673 citations
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TL;DR: A low-cost, solution-processable solar cell, based on a highly crystalline perovskite absorber with intense visible to near-infrared absorptivity, that has a power conversion efficiency of 10.9% in a single-junction device under simulated full sunlight is reported.
Abstract: The energy costs associated with separating tightly bound excitons (photoinduced electron-hole pairs) and extracting free charges from highly disordered low-mobility networks represent fundamental losses for many low-cost photovoltaic technologies. We report a low-cost, solution-processable solar cell, based on a highly crystalline perovskite absorber with intense visible to near-infrared absorptivity, that has a power conversion efficiency of 10.9% in a single-junction device under simulated full sunlight. This "meso-superstructured solar cell" exhibits exceptionally few fundamental energy losses; it can generate open-circuit photovoltages of more than 1.1 volts, despite the relatively narrow absorber band gap of 1.55 electron volts. The functionality arises from the use of mesoporous alumina as an inert scaffold that structures the absorber and forces electrons to reside in and be transported through the perovskite.
7,996 citations
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TL;DR: A sequential deposition method for the formation of the perovskite pigment within the porous metal oxide film that greatly increases the reproducibility of their performance and allows the fabrication of solid-state mesoscopic solar cells with unprecedented power conversion efficiencies and high stability.
Abstract: Following pioneering work, solution-processable organic-inorganic hybrid perovskites-such as CH3NH3PbX3 (X = Cl, Br, I)-have attracted attention as light-harvesting materials for mesoscopic solar cells. So far, the perovskite pigment has been deposited in a single step onto mesoporous metal oxide films using a mixture of PbX2 and CH3NH3X in a common solvent. However, the uncontrolled precipitation of the perovskite produces large morphological variations, resulting in a wide spread of photovoltaic performance in the resulting devices, which hampers the prospects for practical applications. Here we describe a sequential deposition method for the formation of the perovskite pigment within the porous metal oxide film. PbI2 is first introduced from solution into a nanoporous titanium dioxide film and subsequently transformed into the perovskite by exposing it to a solution of CH3NH3I. We find that the conversion occurs within the nanoporous host as soon as the two components come into contact, permitting much better control over the perovskite morphology than is possible with the previously employed route. Using this technique for the fabrication of solid-state mesoscopic solar cells greatly increases the reproducibility of their performance and allows us to achieve a power conversion efficiency of approximately 15 per cent (measured under standard AM1.5G test conditions on solar zenith angle, solar light intensity and cell temperature). This two-step method should provide new opportunities for the fabrication of solution-processed photovoltaic cells with unprecedented power conversion efficiencies and high stability equal to or even greater than those of today's best thin-film photovoltaic devices.
7,560 citations