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Photovoltaics
Published in D. Yogi Goswami, Principles of Solar Engineering, 2023
Figure 9.20 shows structural geometries of Methyl ammonium lead iodide (CH3NH3PbI3) which is an ionic photovoltaic absorber with a bandgap of 1.5 eV and a Perovskite structure. The Perovskite structure is an octahedron formed with negative ions (Cations) at the corners and an anion (positive ion) at the center. In this figure, the cations are negative Iodine ions forming an octahedron with a positive Lead ion at the center. The octahedron is stabilized by methyl-ammonium anions forming a cubic surround structure. Over the last decade, researchers have developed a number of Perovskite materials in order to increase the efficiency of the Perovskite solar cells and to increase their stability. In general, Perovskite materials follow the crystal structure of CaTiO3 and are of the type ABX3, where A is a monovalent alkali cation, such as Na+, K+, Li+, Cs+, Rb+ and B is a divalent cation, such as Pb+, Sn+, Ge+ and X is a halogen anion, such as Cl−, Br−, I− and Fl−. Organic-Inorganic Halide-based Perovskite material has an organic monovalent cation A such as, CH3NH3+, CH3CH2NH3+ or NH2CHNH2+. The structural geometries can be octahedral or cuboctahedral as shown in Figure 9.21.
Nanostructured Perovskites for Light-Emitting Diodes
Published in Tuan Anh Nguyen, Ram K. Gupta, Nanotechnology for Light Pollution Reduction, 2023
Felipe M. de Souza, Ram K. Gupta
Perovskite materials can be synthesized in several forms such as polycrystals, single crystals, thin films, or powders. Also, they can be generally divided into two categories which are the all-inorganic perovskite with the ABX3 general formula, as previously mentioned, and the organic-inorganic hybrid perovskites which are composed of a cationic organic segment, a divalent metal, and a halide. Based on that, the all-inorganic perovskites nanocrystals class has been explored as means to serve as a more stable nanomaterial when compared to organic-inorganic hybrid perovskite. In that sense, the methylamine cations that have a diameter of 217 pm are replaced with Cs cations that have a smaller diameter of 167 pm, which can lead to CsPbX3 structures with higher phase and photostability. Yet, the smaller size for the cation makes the cubic phase of CsPbI3 unstable when compared to the orthorhombic phase. To address that, amine ligands can be used as they act as a template enabling the perovskite to maintain its structure under room temperature. Within that line, approaches to synthesize perovskites based on cesium lead halides (CsPbX3) have been developed through the hot injection approach.
Heterojunction Perovskite Oxide/ Halide Materials for Photocatalytic Solar Hydrogen Production
Published in A. Pandikumar, K. Jothivenkatachalam, S. Moscow, Heterojunction Photocatalytic Materials, 2022
Nagalingam Rajamanickam, S. S. Kanmani, Kathirvel Ramachandran
The large-scale production of electricity by silicon cells is too expensive. In contrast, enormous literature is available on dye sensitized solar cells, semiconductor sensitized solar cells, and thin film solar cells that utilize cheapest materials. From 2009 onward, a new related type of material called perovskite entered into the solar energy field with highly certified solar to energy conversion efficiency of 25.2%. The rapid growth of perovskite materials (within 10 years) impressed the researchers to promote this for large-scale commercialization, but now its stability with long lifetime becomes a major challenge [43]. There are two key factors to justify how the perovskite solar cells received such prominent attention within a short span of time: one is solar conversion efficiency, which equalled cadmium telluride (CdTe) and exceeded copper indium gallium selenide (CIGS) performance, and the other is increased open circuit voltage due to the utilization of 70% of incident photons. Perovskite-based solar cells offer many advantages, such as tunable bandgap by changing chemical composition, superior charge carrier mobility, good absorption coefficient, ambipolar charge transport, favorable band alignments, long charge carrier lifetime, and long charge carrier diffusion length [44]. Here the latest breakthroughs as effective light harvesting agent in solar cells are perovskite materials.
A review of memristor: material and structure design, device performance, applications and prospects
Published in Science and Technology of Advanced Materials, 2023
Yongyue Xiao, Bei Jiang, Zihao Zhang, Shanwu Ke, Yaoyao Jin, Xin Wen, Cong Ye
A serious deficiency of perovskite materials is lack of environmental stability. To solve this problem, Cheng et al. firstly utilized lead-free double perovskite Cs2AgBiBr6 for environmentally robust memristors [94]. A memristor with ITO/Cs2AgBiBr6/Au structure exhibited performance of 105 seconds of retention and 104 times of mechanical bending (Figure 2(c)). Most importantly, the performance of the memristor remains robust in harsh environments. The device could last 10 s in alcohol burner flames, and withstand a temperature of 180°C or 60Co γ-ray irradiation at a dose of 5 × 105 rad (SI) (Figure 2(f)). These parameters are superior to those of commercial flash memory devices [94]. Although memristors based on perovskite have been hotly investigated, the perovskite memristor still has some disadvantages like the incompatibility with CMOS processes, which limits their practical applications.
Perovskite modifiers with porphyrin/phthalocyanine complexes for efficient photovoltaics
Published in Journal of Coordination Chemistry, 2022
As one effective way to alleviate the energy crisis, achieve carbon peak and carbon neutrality, solar cells are promising. Perovskite materials have excellent light absorption and electrical conduction properties [1], as well as advantages of low cost, concise device structure and simple preparation methods, which make it important in solar cells, energetic materials [2], etc. Since the advent of perovskite solar cells (PSCs) just a decade ago, the power conversion efficiency (PCE) of PSCs has increased from the initially reported 3.8% [3] to 25.7% [4] and is considered as a candidate for mainstream photovoltaic devices. Figuring out ways to improve the efficiency and stability of PSCs is of the utmost significance at present. The construction of large-area devices, which is the major challenge for the commercialization of PSCs, may be handled by delaying or reducing the degradation of perovskite materials. Apart from the exogenous degradation mediated by water [5, 6], light [7] and temperature [8], the endogenous degradation caused by defects and ion migration [9] are of interest. Researchers have managed to optimize properties of perovskite materials using composition regulating [10, 11] and additives [12, 13].
Crystal structure, vibrational spectra, optical properties and thermal behavior of the 1D perovskite (2-amino-4-methylpyridinium)trichlorocadmate(II) (C6H9N2)1 ∞[CdCl3]
Published in Journal of Coordination Chemistry, 2021
Fatma Garci, Hammouda Chebbi, Axel Klein, Mohamed Faouzi Zid
The most simple and versatile method to produce such perovskite materials from solutions is the mixing of metal salts MXn with the organic bases under acidic conditions. However, this method might not only yield the target 1 D (m = 1), 2 D (m = 2) or 3 D (m = 3) (An+)m∞[MX3n–] perovskite structures; also salt-like compounds (An+)[MXcnn–] (cn = 4 or 6) containing isolated tetra- or hexa-halido metalates can be the product of such a reaction. These isolated halidometalates are sometimes referred to as zero-dimensional (0 D) perovskites, but they do not contain structural features typical for perovskites and consequently their electronic properties are not suitable for photovoltaic applications [3, 7, 12]. Additionally, from this synthesis approach, simple complexes of the metals with the organic bases and further inorganic ligands might result [6].