Method to control the optical properties: Band gap energy of mixed halide Organolead perovskites

Ezealigo, Blessing N.; Nwanya, Assumpta C.; Ezugwu, Sabastine; Offiah, S. U.; Obi, Daniel; Osuji, R. U.; Bucher, R.; Mâaza, M.; Ejikeme, Paul M.; Ezema, Fabian I.

doi:10.1016/j.arabjc.2017.09.002

Cited by 25 publications

(14 citation statements)

References 37 publications

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“…A and B are cations of large sizes such as Rb, Cs, Pb, Sn and organic substances whereas X can be a halide (Cl, Br and I). It is well-known that the desired electrical and optical properties of solar cells for potential applications of this class of materials can be tailored by varying the type and amount of substitution into the lattice for any of the three species A, B and X [12,13]. These compounds have attracted tremendous attention in the last few decades because of their importance in light-emitting diodes, spintronic-based devices, energy storage devices and solar cell applications due to their good light absorbing properties [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

A comparative study of structural, electronic and optical properties of cubic $$\hbox {CsPbI}_{3}$$: bulk and surface

et al. 2019

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In order to acquire a reasonable description of the structural, electronic and optical properties of the perovskite compound CsPbI 3 , first principle calculations have been computed by density functional theory implemented in the WIEN2k code. The calculations are presented within PBE-sol for exchange correlation functions coupled with modified-Becke-Johnson (mBJ) exchange potential. The (001) surfaces of CsPbI 3 for varying thicknesses have been constructed using the Structeditor program implemented in the WIEN2k code. The lattice constant, band gap and DOS have been computed. The CsPbI 3 bulk and surface exhibit a direct band gap located at the R symmetry point of the Brillouin zone. The band gap approaches experimental values when the exchange correlation function is coupled with mBJ. The optical properties of CsPbI 3 were computed in terms of dielectric properties, refractive index, extinction coefficient, absorption coefficient, conductivity, reflectivity and energy loss. The direct band gap nature and high-absorption power of the surfaces of CsPbI 3 in the (001) direction in the infrared, visible and ultraviolet energy range make it suitable for use in optical and optoelectronic devices.

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Section: Introductionmentioning

confidence: 99%

A comparative study of structural, electronic and optical properties of cubic $$\hbox {CsPbI}_{3}$$: bulk and surface

et al. 2019

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“…The value of σ at these peaks is 2.64 × 10 9 Sm −1 for Cs 2 AgCrBr 6 , 2.76 × 10 9 Sm −1 for Rb 2 AgCrBr 6 , and 2.84 × 10 9 Sm −1 for K 2 AgCrBr 6 . For comparison, the average value of σ for MAPbI 3 thin films was reported to be 6 × 10 5 Sm −1 [ 100 ].…”

Section: Resultsmentioning

confidence: 99%

A2AgCrBr6 (A = K, Rb, Cs) and Cs2AgCrX6(X = Cl, I) Double Perovskites: A Transition-Metal-Based Semiconducting Material Series with Remarkable Optics

Varadwaj

2020

Nanomaterials

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With an interest to quest for transition metal-based halogenated double perovskites AB′B″X6 as high performance semiconducting materials for optoelectronics, this study theoretically examined the electronic structures, stability, electronic (density of states and band structures), transport (effective masses of charge carriers), and optical properties (dielectric function and absorption coefficients, etc.) of the series A2AgCrBr6 (A = K, Rb, Cs) using SCAN + rVV10. Our results showed that A2AgCrBr6 (A = Rb, Cs), but not K2AgCrBr6, has a stable perovskite structure, which was revealed using various traditionally recommended geometry-based indices. Despite this reservation, all the three systems were shown to have similar band structures, density of states, and carrier effective masses of conducting holes and electrons, as well as the nature of the real and imaginary parts of their dielectric function, absorption coefficient, refractive index, and photoconductivity spectra. The small changes observed in any specific property of the series A2AgCrBr6 were due to the changes in the lattice properties driven by alkali substitution at the A site. A comparison with the corresponding properties of Cs2AgCrX6 (X = Cl, I) suggested that halogen substitution at the X-site can not only significantly shift the position of the onset of optical absorption found of the dielectric function, absorption coefficient and refractive spectra of Cs2AgCrCl6 and Cs2AgCrI6 toward the high- and low-energy infrared regions, respectively; but that it is also responsible in modifying their stability, electronic, transport, and optical absorption preferences. The large value of the high frequency dielectric constants—together with the appreciable magnitude of absorption coefficients and refractive indices, small values of effective masses of conducting electrons and holes, and the indirect nature of the bandgap transitions, among others—suggested that cubic A2AgCrBr6 (A = Rb, Cs) and Cs2AgCrCl6 may likely be a set of optoelectronic materials for subsequent experimental characterizations.

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“…where A is the absorbance and t is the film thickness . The bandgap values show a small increase; the bulk perovskite sample presents a value of 1.60 eV, and the octylammonium, decylammonium, and dodecylammonium films present only a small change in the bandgap values: 1.60, 1.61, and 1.61 eV, respectively.…”

Section: Resultsmentioning

confidence: 99%

In Situ 2D Perovskite Formation and the Impact of the 2D/3D Structures on Performance and Stability of Perovskite Solar Cells

et al. 2019

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Hybrid organic and inorganic perovskite solar cells lack long‐term stability, and this negatively impacts the widespread application of this emerging and promising photovoltaic technology. Herein, aiming to increase the stability of perovskite films based on CH3NH3PbI3 and to deeply understand the formation of 2D structures, solutions of alkylammonium chlorides containing 8, 10, and 12 carbons are introduced during the spin‐coating on the surface of 3D perovskite films leading to the in situ formation of 2D structures. It is possible to identify the chemical formulae of some 2D structures formed by X‐ray diffraction and UV–vis analysis of the modified films. Interestingly, the increase in the stability of the CH3NH3PbI3 films due to the formation of a 2D + 3D perovskite network is only possible in planar TiO2 substrates. The increase in stability of the CH3NH3PbI3 films follows the surfactant molecule order: octylammonium (8C) > decylammonium (1 °C) > dodecylammonium (12C) chlorides > standard. An increase of 17.6% in the lifetime of the devices assembled with octylammonium‐modified perovskite film is observed compared with that of the standard device, which is directly linked to the improvement of the charge carrier lifetimes obtained from time‐correlated single photon counting measurements.

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Method to control the optical properties: Band gap energy of mixed halide Organolead perovskites

Cited by 25 publications

References 37 publications

A comparative study of structural, electronic and optical properties of cubic $$\hbox {CsPbI}_{3}$$: bulk and surface

A comparative study of structural, electronic and optical properties of cubic $$\hbox {CsPbI}_{3}$$: bulk and surface

A2AgCrBr6 (A = K, Rb, Cs) and Cs2AgCrX6(X = Cl, I) Double Perovskites: A Transition-Metal-Based Semiconducting Material Series with Remarkable Optics

In Situ 2D Perovskite Formation and the Impact of the 2D/3D Structures on Performance and Stability of Perovskite Solar Cells

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