In this study the efficiency limits of binary, ternary and quaternary transition metal dichalcogenides alloys are evaluated as a function of film thicknesses, light-trapping, and the detrimental impact of non-radiative recombination. To achieve this, experimentally measured absorption spectra, various formalisms, and different solar spectra have been employed. The results show that efficiency and current increase with film thickness and lighttrapping, albeit at the expense of reduced voltage. In all cases, non-radiative recombination reduces both efficiency and voltage. From the results, films as thin as 1 nm (10 nm) could achieve up to 14 % (29 %) power conversion efficiency with light-trapping. Without LT these values are considerably reduced to 1 % (7 %).

In this study the photovoltaic potential of two-dimensional Transition Metal Dichalcogenide alloys is evaluated by considering several efficiency metrics, absorber layer thicknesses, light-trapping strategies, and both radiative and bulk photovoltaic effects across different photon energy ranges, from monochromatic spectra to the full AM1.5G solar spectrum. The results using the full solar AM1.5G spectrum and light-trapping show that films as thin as 1 nm (10 nm) could achieve up to 14

Multi-band semiconductors are promising candidates for high-efficiency photovoltaic devices. Various technological methodologies have been explored and put into practice. However, the efficiencies achieved experimentally fall short of expectations. In this study, considering the relative scale of all inter-band absorption coefficients, it has been determined that the anticipated efficiencies are difficult to attain. Furthermore, with all the results and considering the mathematical and boundary properties, a fit as a function of the absorptivities for efficiencies and energies of all examined multi-band solar cell types has been obtained.

To determine whether the incorporation of triiodide ions into Bi-based hybrid compounds can serve as a substitute for iodoplumbates perovskites without diminishing photovoltaic efficiency, we analyzed the contributions of anions and triiodide ions to the absorption coefficients and conversion efficiencies across several compounds, both with and without triiodide ions. The electronic properties and absorption coefficients were obtained from first principles. To determine and quantify the key contributors to the optical gaps, the absorption coefficients and solar cell efficiencies are split as exact many-species expansions. The results reveal that while the triiodide contribution to the absorption coefficients and efficiencies is substantial, the primary distinction between compounds is attributed to the Bi-Bi interatomic distances. Nevertheless, the introduction of triiodide ions results in an increase in efficiency compared to the precursor compounds that lack triiodide ions.

The photovoltaic use of iodoplumbates perovskites is limited because of lead toxicity and its instability. An alternative is the iodobismuthate compounds. In this work, the microscopically optical properties of two iodobismuthate compounds, (C28H40N4)(Bi4I18) and (C6H8N)(BiI5), are obtained using first principles. To relate these properties to the structure and to analyze the effect of the iodine linker atoms in these compounds, we split the absorption coefficients into an exact many-specie expansion. The results indicate that the optical gap and the optical properties are determined by the anionic fragment of these compounds. The presence of iodine linker atoms results in a reduction in the energy gap and a larger absorption near the gap.

Complex lead iodide hybrid perovskites show high photovoltaic efficiency, but their use in solar cells may be limited due to Pb toxicity and its great bioavailability because of its solubility in water. Iodobismuthates can emerge as a promising alternative for solar cells, having no toxicity and exhibiting high stability in relation to the oxidation in air. To know if the iodoplumbates can be substituted with less toxic iodobismuthates without reducing the photovoltaic efficiency, microscopic contributions to the absorption coefficients are analyzed for two compounds. The absorption coefficients were obtained from first principles. To identify and quantify the most important contributions to the optical gaps, the absorption coefficients are split as an exact many-species expansion. From the results, the electronic and optical gaps are different. Additionally, the optical gap and the optical properties are rather insensitive to the cationic structure.

To know if Pb can be substituted by less toxic Mg without reducing the photovoltaic efficiency of the methyl‐ammonium lead iodide perovskites, the microscopic contributions to the absorption coefficients and efficiencies are analyzed as a function of the gradual substitution of Pb by Mg. The absorption coefficients are obtained from first principles and used later to obtain efficiencies. To identify and quantify the most important contributions to the photovoltaic properties as a function of cell thickness, both the absorption coefficients and efficiencies are split as an exact many‐species expansion. From these results, the substitution of Pb by Mn would lead to solar cells with similar photovoltaics characteristics, except if the solar cells are ultra‐thin.

Methyl-ammonium lead iodide perovskite crystallizes in different structures depending on the temperature: orthorhombic, tetragonal and cubic. An important point to be considered is the effect of the microscopic properties of the different structures on the optical and photovoltaic properties. Using first principles we obtain the absorption coefficients that will determine the absorption of solar radiation. In order to analyze the contributions of the different atoms to the absorption coefficients we split them into a many-species expansion. Using a similar methodology we also split the efficiencies as a many-species expansion. It allows the contribution of the atomic species to be identified and quantified to the absorption coefficients and to the solar cell efficiency of the different phases. Additionally the effect of the cell thickness w is quantified.

Methyl-ammonium lead, tin, and germanium iodide perovskites are very interesting compounds for photovoltaics because they present a high absorption capacity for solar radiation. The microscopic contributions to the absorption coefficients and efficiencies of these perovskites are analyzed and quantified. To achieve this goal, both absorption coefficients and efficiencies are split as an exact many-species expansion. The absorption coefficients have been obtained from first-principles and have been used later to obtain efficiencies. Furthermore, by using the absorption coefficients instead of the band gap as the criterion for absorption, the efficiencies have also been quantified as a function of cell thickness. The contributions of inorganic cations are larger than those of organic cation atoms for low energies. As a consequence, as the thickness decreases, the contribution to the efficiency of inorganic cations and iodine increases, whereas that of the organic cation decreases.

The effect of 14 organic cations on the optical properties of the lead iodine perovskite is analyzed. The electronic and optical properties are obtained using first principles. The absorption coefficients are split into inter-atomic species components in order to quantify all of the contributions. For energies close to the bandgaps, the main contribution is from the Pb-Pb intra-species transitions. For higher energy this contribution is still important in addition to I-I and Pb-I contributions, and to the 3 and 4 species term. Almost all absorption properties are qualitatively similar. Furthermore, this absorption coefficient splitting also allows the optical characteristics that the substitution of Pb by another element should satisfy to be identified in order to reduce the toxicity because of Pb while maintaining a high absorption capacity.

Lead halide perovskites are promising semiconductors for solar energy conversion because of their electronic and optical properties. Using first principles we obtain these properties for the chlorine, bromine and iodine lead halide perovskites. In order to analyze the contributions of the different atoms and orbitals to the absorption coefficient, we split them into a many-species expansion. It allows the atomic and orbital contributions to be identified and quantified as a photon energy function.

Intermediate band semiconductors represent an alternative to increasing the efficiency of solar energy converters. However, the experimental results obtained so far do not reflect the expectations. Many factors are unable to explain it. In this work we have removed some of the approximations used for the efficiency evaluation taking into account the occupation of the bands, the inter-band absorption coefficients, and the optical thickness simultaneously. In many cases the results lower the expectations of the maximum efficiencies.

This Data article presents the absorption coefficients of Lead Iodine perovskites using 14 different organic cations. In addition, the absorption coefficients have been split into inter-atomic species components in order to quantify all of the contributions. For more details on the methodology, interpretation and discussion, refer to the full length article entitled “Effect Of the organic cation on the optical properties of lead iodine perovskites”. https://doi.org/10.1016/j.solmat.2019.110022 Data may be useful for future research, and to identify the contribution of different species to the absorption.

The iron vanadium oxide semiconductor Fe2V4O13 has interesting properties as an absorbent material for the conversion of solar energy. In this work the electronic, magnetic and optical properties of Fe2V4O13 have been obtained and analyzed from theoretical calculations and compared with experimental results. From the results, the main contributions to the optical properties come from the transitions between O-V states. The optical properties have been used to evaluate this compound as a solar energy converter using mono- and multi-junction configurations.

We evaluate the constrained efficiently of the coupling between a photovoltaic device and a device supplying a constant voltage and/or current. The former can be used with an electrochemical device to store solar to chemical energy. Single- and multi-gap semiconductors are used to evaluate the photovoltaic devices. Unlike other approaches, no approximation is made to fix the output voltage and/or current and the method is not limited to non-degenerate semiconductors. The problem is solved globally with a generalized methodology that allows for the analysis of any type of absorption coefficients and solar spectra.

In most cases, when the efficiencies of a single or multi-gap (with intermediate bands) solar cell are evaluated, the energy dependence of the absorption coefficients is ignored. In this work we will evaluate the range of optical thickness and average absorption coefficients in which this dependence should be considered. For this study we use different absorption coefficients generated randomly as a function of the energy. In many practical cases, the efficiencies are lower than those expected.

The CuFeO2 semiconductor, a delafossite compound with a lower band gap, has electronic and optical properties of interest for absorbing solar radiation in solar converters. In order to evaluate its potential the optical properties and their decomposition into atomic contributions are obtained using first-principles. Both ferromagnetic and antiferromagnetic spin alignments are considered. According to the results the structure, the Fe-Cu transitions makes almost no contribution to the absorption. Then, by using the absorption coefficient, the maximum absorption efficiencies, voltages, and currents of the solar conversion are found. The results indicate it as being a good candidate for solar cells but it does not generate enough output voltage for water-splitting.

An ideal solar energy to electricity or fuel converter should work without the use of any external bias potential. An analysis of self-sufficiency when CaFe204 is used to absorb the sunlight is carried out based on the CaFe2Ü4 absorption coefficient. We started to obtain this coefficient theoretically within the experimental bandgap range in order to fix the interval of possible values of photocurrents, maximum absorption efficiencies, and photovoltages and thus that of selfsufficiency considering only the radiative processes. Also for single-gap CaFe2Ü4, we evaluate an alternative for increasing the photocurrent and maximum absorption efficiency based on inserting an intermediate band using high doping or alloying.

Delafossite CuRhO2 is considered as a solar radiation absorbing material for solar cells and solar-to-fuel conversion by carrying out the water splitting. The absorption features depend on the optical properties. To obtain the absorption coefficient we use the density functional theory with orbital-dependent one-electron potentials. As well as analyzing the largest contributions, the absorption coefficients have been split into different species contributions. Then, the maximum absorption efficiencies, photo-currents and photo-voltages of the sunlight conversion have been obtained using the absorption coefficients, the device thickness, and the incident spectrum as optimization criteria. Furthermore the non-radiative recombination and some voltage losses are analyzed.

An analysis of BiFeO3, focusing on its absorption properties, is carried out using experimental results from the literature and first-principles. In order to identify the different contributions to the absorption coefficient, the results have been split into inter- and intra-atomic contributions. Its potential as a photovoltaic material has been evaluated using both theoretical and experimental optical results. Because of the ferroelectric properties, we have considered two mechanisms for generating photocurrent: the traditional radiative and the ferroelectric or photovoltaic effects. The efficiencies, when ferroelectric photogeneration coexists with the traditional photovoltaic mechanism, are only slightly larger than when only the latter is considered. However, the increase in efficiency is significant with just multi-gap solar cells.