Potential Candidate For Photovoltaic Applications Research Articles

Integrative approach of machine learning and symbolic regression for stability prediction of multicomponent perovskite oxides and high-throughput screening

This work unfolds a robust and interpretable strategy for evaluating the stability and potential photovoltaic application of 6526 multicomponent perovskite oxides, employing a synergetic methodology that intertwines advanced machine learning (ML) algorithms and symbolic regression based on genetic programming. Initially, ML algorithms, namely XGBoost, LightGBM, and random forest, were harnessed, with elemental oxidation state and electronegativity serving as input features, achieving R2 values of 0.98, 0.98, and 0.74, respectively, on the test set for predicting the formation enthalpy, a criterion for perovskite stability. Despite the amplified interpretability offered by SHAP analysis, the inherent “black-box” nature of ML obfuscates a transparent understanding of intrinsic relations between input features and performance. To surmount this, symbolic regression introduced not only elucidates a clear functional relationship between input features and perovskite stability but also achieves a commendable R2 of 0.79 on the test set. Subsequent high-throughput screening, based on perovskite stability ranking, designated the top 500 stable perovskites for band gap calculation using the PBE functional, wherein DyNdHf2O6, CeEuAl2O6, and CeSrAl2O6 emerged as potential candidates for photovoltaic applications and were subjected to further electronic structure simulations employing the HSE06 functional, encompassing density of states, band structure, charge density, and optical absorption spectra. Ultimately, CeEuAl2O6, boasting an optical direct bandgap of 2.31 eV and minimal electron-hole wavefunction overlap, stands out as the prime choice for photovoltaic materials. This research not only pioneers the exploration of enhancing the interpretability of ML but also propels theoretical guidance for the evolution of photovoltaic cells by bridging predictive modeling with high-throughput screening.

Chemical similarity-based design of materials for organic solar cells: Visualizing the generated chemical space of polymers

Potential candidates for photovoltaic applications can be found using chemical similarity analysis. Compounds with similar structural characteristics may perform similarly. Designing of materials for organic solar cells (OSCs) is a difficult and time-consuming process. An existing polymer database is mined to find polymers for OSCs, three polymers (PM6, PBT7-Th, and D18) are used as standard. However, good polymers are not found from this database. A large database of polymers is generated using an automatic method that is implemented on RDkit. Synthetic accessibility of generated polymers is calculated. Similarity analysis is conducted to search the polymers from the generated database. Similarity analysis is performed using Tanimoto index. Large number of potential candidates for polymer solar cells are found. Structure Activity Landscape Index (SALI) plot is used to quantitatively characterize activity landscapes.

A Halide‐Based Perovskite CsGeX3 (X = Cl, Br, and I) for Optoelectronic and Piezoelectric Applications

AbstractBy means of the study of the first principles within the framework of density functional theory, the inorganic metal halide perovskite CsGeX3 (X = Cl, Br, and I) is thoroughly investigated for its potential application in the field of green energy harvest. The structural, electronic, optical, mechanical, and piezoelectric properties have been calculated. Herein, the computed electronic properties reveal a direct bandgap semiconducting nature with electronic bandgap E = 2.01, 1.38, and 0.85 eV for X = Cl, Br, and I, respectively. Since the most prominent absorption peak falls within the vis–UV region, this implies that they are the potential candidates for photovoltaic applications. To check and verify the thermal stability, the MD simulation was performed with time steps up to 5 ps. The highest piezoelectric coefficient values are 0.731, 1.829, and 12.48 C m−2 for X = Cl, Br, and I, respectively. The higher piezoelectric responses indicate the signature of the efficient energy materials for energy harvest through electromechanical processes.

High‐Throughput Screening of High‐Entropy Fluorite‐Type Oxides as Potential Candidates for Photovoltaic Applications

AbstractHigh‐throughput (HT) synthesis and HT characterization techniques are becoming increasingly important due to the ever‐increasing complexity of materials and applications of advanced functional compounds. This work reports on the high‐throughput compilation of material libraries of high‐entropy oxides with fluorite crystal structure and tunable band gaps to be used as, e.g., semiconductors for photovoltaic applications. The material libraries cover the high‐entropy range of rare‐earth oxides with 5, 6, and 7 different cations (Ce, La, Sm, Pr, Tb, Y, and Zr) in near equimolar concentrations, but also the medium entropy range with 4 cations. The atmosphere used during or after synthesis is found to have a large effect on the band gap of these materials. Multivalent rare‐earth cations such as Ce/Pr/Tb enable reversible tuning of the band gap between 2.0 and 3.5 eV upon calcination under various oxidizing and reducing atmospheres. The high‐entropy fluorite oxides with smaller band gaps exhibit high electron mobility and transport energy levels compatible with common solar cell architectures.

First-Principles Calculations to Investigate Structural, Electronic, Optical and Magnetic Properties of Pyrochlore Oxides Eu2Tm2O7 (Tm = Hf, Sn, Zr) for Energy Applications

Three newly designed pyrochlore oxides, Eu2Tm2O7 (Tm = Hf, Sn, Zr), are analyzed for their magnetic, optical and electronic properties using ab-initio calculations within the context of density functional theory (DFT). We can refer these compounds as direct bandgap materials because there is a very slight difference between the height of bands at the Γ- and M-point. It is observed that bandgap engineering can be performed by replacing Hf with Sn and Zr. It is observed from total density of states (TDOS) plots that shape and height of curves is not the same in spin up and spin down channels, showing significant magnetic moment in these compounds. It is evident from magnetic properties that a major portion of total magnetic moment (mtot) comes from Eu-atoms. In all compounds, the magnetic moment of O, Hf, Sn and Zr atoms is negative, whereas the magnetic moment of Eu-atoms is positive, showing their antiparallel arrangement. In both spin channels, significant absorption of the incoming photons is also shown by these compounds in the ultraviolet (UV) region. We can conclude on the basis of Rω that these compounds can be utilized in applications such as anti-reflecting coatings. These compounds are potential candidates for photovoltaic applications, such as solar cells, due to efficient absorption of incoming photons in visible and UV regions.

Effect of surface termination on electronic and optical properties of lead-free tin-based eco-friendly perovskite solar cell: a first principal study.

The lead (Pb)-based halide perovskites have been reported to be promising materials for photovoltaic applications; however, the presence of toxic lead in them concerns the environmental and health issues. In this work, we have, therefore, studied the lead-free and non-toxic tin-based halide perovskite, CsSnI3, which is an eco-friendly material with high power conversion efficiency, thus, being a potential candidate for photovoltaic applications. We have investigated the influence of CsI and SnI2-terminated (001) surfaces on structural, electronic and optical properties of lead-free tin-based halide perovskite CsSnI3 from the first principal calculations, based on density functional theory (DFT). The calculations of electronic and optical parameters are performed under the parameterisation of PBE_Sol for exchange-correlation functions conjugated with modified- Beche-Johnshon (mBJ) exchange potential. The optimised lattice constant, the energy band structure and the density of states (DOS) have been calculated for the bulk and different terminated surface structures. The optical properties of CsSnI3 are computed in terms of the real and imaginary part of absorption coefficient, dielectric function, refractive index, conductivity, reflectivity, extinction coefficient and electron energy loss. The photovoltaic characteristics for the CsI-termination are found to be better than the bulk and SnI2-terminated surfaces. This study reveals that optical and electronic properties can be tuned by selecting proper surface termination in halide perovskite CsSnI3. The CsSnI3 surfaces exhibit semiconductor behaviour with a direct energy band gap and a high value of absorption power in the ultraviolet and visible region, rendering these inorganic halide perovskite materials important for the eco-friendly and efficient optoelectronic devices.

Crystal lattice and electronic and transport properties of Janus ZrSiSZ2 (Z = N, P, As) monolayers by first-principles investigations.

From the extending requirements for using innovative materials in advanced technologies, it is necessary to explore new materials for relevant applications. In this work, we design new two-dimensional (2D) Janus ZrSiSZ2 (Z = N, P, As) monolayers and investigate their crystal lattice and dynamic stability by using density functional theory investigations. The two stable structures of ZrSiSP2 and ZrSiSAs2 are then systematically examined for thermal, energetic, and mechanical stability, and electronic and transport properties. The calculation results demonstrate that both the ZrSiSP2 and ZrSiSAs2 monolayers have good thermal stability at room temperature and high energetic/mechanical stabilities for experimental synthesis. The studied structures are found to be in-direct semiconductors. Specifically, with moderate band-gap energies of 1.04 to 1.29 eV for visible light absorption, ZrSiSP2 and ZrSiSAs2 can be considered potential candidates for photovoltaic applications. The applied biaxial strains and external electric fields slightly change the band-gap energies of the monolayers. We also calculate the carrier mobilities for the transport properties based on the deformation potential method. Due to the lower effective masses, the carrier mobilities in the x direction are higher than those in the y direction. The carrier mobilities of the ZrSiSP2 and ZrSiSAs2 monolayers are anisotropic not only in transport directions but also for the electrons and holes. We believe that the results of our work may stimulate further studies to explore more new 2D Janus monolayers with novel properties of the MA2Z4 family materials.

Study on the structural, electronic and optical properties of double-perovskite halides Cs2AgSbX6 (X=I, Br, Cl) based on first-principles

The structural, electronic and optical properties of Cs2AgSbX6 (X = I, Br, Cl) were investigated based on first-principles calculation in this paper. The stability of these materials can be determined by the binding energy, formation energy and two tolerance factors. The results indicate that three materials are indirect band gap, with ideal band gap range of materials for photoelectric applications. The bandgap values of Cs2AgSbI6, Cs2AgSbBr6 and Cs2AgSbCl6 are 0.84 eV, 1.47 eV and 1.87 eV, respectively. Compared with other perovskites, the effective masses of holes of Cs2AgSbX6 are smaller, which is beneficial to the carrier transport and the performance improvement of optoelectronic devices. Moreover, the exploration of optical characteristics reveal the potential utilization of Cs2AgSbX6 in photovoltaic devices. Based on these calculated results, the double-perovskite Cs2AgSbX6 is a potential candidate for photovoltaic applications.

The effect of the A-site cation on the stability and physical properties of vacancy-ordered double perovskites A2PtI6 (A = Tl, K, Rb, and Cs)

In this article, a theoretical study on the structural, mechanical, electronic and optical properties of vacancy-ordered double perovskites A2PtI6 (A ​= ​Tl, K, Rb, and Cs) is conducted for the first time. The calculated lattice constants of each compound are consistent well with the reported experimental data. The tetragonal phase is adopted for Tl2PtI6 and K2PtI6, while Rb2PtI6 and Cs2PtI6 show the cubic phase. The results suggest that four compounds show good stability and the stability order is Cs2PtI6 ​> ​Rb2PtI6 ​> ​K2PtI6 ​> ​Tl2PtI6. The mechanical stability and ductile nature of each compound are confirmed. It is found that A2PtI6 (A ​= ​Tl, K) and A2PtI6 (A ​= ​Rb, Cs) are indirect and direct bandgap semiconductors, respectively. The predicted indirect and direct band gaps of four compounds are between 1.2 and 1.6 ​eV based on the HSE06 method. Rb2PtI6 and Cs2PtI6 have similar absorption curves. Moreover, Tl2PtI6 and K2PtI6 show stronger light absorption capacity. These four compounds are potential candidates for photovoltaic applications.

Approaching Theoretical Band Gap of ZnSnN2 Films via Bias Magnetron Cosputtering at Room Temperature

Zinc tin nitride (ZnSnN2) is a promising semiconductor candidate for solar cell applications and optoelectronic devices. However, the practical use of this material has been limited by several issues as, among others, oxygen contamination, a very high concentration of free carriers, and the difficulty to reach the theoretically predicted band gap. Here, we deposit thin films of ZnSnN2 by reactive DC magnetron cosputtering at room temperature with an RF bias power (Pb) in the range of 0–50 W. Using first principles calculations, we explore the structural and optoelectronic properties that are favorably compared to experimental results. We demonstrate that the optical band gap energy can be decreased from 1.7 to 1.34 eV, close to the predicted value of 1.37 eV. The free electron concentration is decreased down to 1017 cm–3 which results in the reduction of the absorption by free electrons in the IR range. In addition, in a given range of applied bias powers, we observe a densification of the films and a significant decrease of their oxygen contamination from 6.7 down to 2.0 at. %. The study underlines that a value of 20 W power bias leads to the optimal structural, optical, and electrical properties. Our results provide an interesting method to obtain a potential candidate for photovoltaic applications, in an environmentally friendly way, for low-cost industrialization.

Polarization‐Modulated Photovoltaic Effect at the Morphotropic Phase Boundary in Ferroelectric Ceramics

AbstractFerroelectric materials, which exhibit switchable polarization, are potential candidates for photovoltaic applications owing to their intriguing charge carrier separation mechanism associated with polarization and breaking of inversion symmetry. To overcome the low photocurrent of ferroelectrics, extensive efforts have focused on reducing their bandgaps to increase the optical absorption of the solar spectrum and thus the power conversion efficiency. Here, a new avenue of enhancing photovoltaic performance via engineering the polarization across a morphotropic phase boundary (MPB) is reported. Tetragonal compositions in the vicinity of the MPB in a PbTiO3‐Bi(Ni1/2Ti1/2)O3 solid solution are shown to generate up to 3.6 kV cm−1 photoinduced electric field and 6.2 µA cm−2 short‐circuit photocurrent, multiple times higher than its pseudocubic counterpart under the same illumination conditions with excellent polarization retention. This enhancement allows the investigation of the correlation between the polarization switching and photovoltaic switching, which enables a controllable multistate photocurrent. Combined with a bandgap of 2.2 eV, this material exhibits a sizable photoresponse over a broad spectral range. These findings provide a new approach to improve the photovoltaic performance of ferroelectric materials and can expand their potential applications in optoelectronic devices.

Effect of substrate temperature on reactive RF magnetron sputtered SnO2 thin films for photovoltaic applications

SnO2 thin films were deposited using reactive RF magnetron sputtering technique at different substrate temperatures such as RT (S1), 200 °C (S2) and 400 °C (S3) in order to obtain highly crystalline as well as highly transparent films. The effect of substrate temperature on the structural, optical and electrical properties of SnO2 thin films was also studied. The observed XRD patterns indicated the formation of SnO2 in tetragonal phase with primitive lattice structure. UV–Vis-NIR spectroscopic analysis exhibited the high optical transparency (>90%) at the wavelength of 600 nm. Hall Effect measurements demonstrated the n-type conductivity of SnO2 thin films with high carrier concentration (-2.40 × 1020 to −8.40 × 1018 cm−3) and mobility (1.62 to 10.83 cm2/Vs) as well as low resistivity in the order of 10-2 Ω.cm for S1-S3. However, S2 (200 °C) is considered as potential candidate for photovoltaic applications because of reasonably high carrier concentration, enhanced crystalline nature, and also low processing temperature in addition to the suitable optical band gap (3.7 eV).

Indirect-to-direct band gap transition and optical properties of metal alloys of Cs2Te1−xTixI6: a theoretical study

In recent years, double perovskites have attracted considerable attention as potential candidates for photovoltaic applications. However, most double perovskites are not suitable for single-junction solar cells due to their large band gaps (over 2.0 eV). In the present study, we have investigated the structural, mechanical, electronic and optical properties of the Cs2Te1−xTixI6 solid solutions using first-principles calculations based on density functional theory. These compounds exhibit good structural stability compared to CH3NH3PbI3. The results suggest that Cs2TeI6 is an indirect band gap semiconductor, and it can become a direct band gap semiconductor with the value of 1.09 eV when the doping concentration of Ti4+ is 0.50. Moreover, an ideal direct band gap of 1.31 eV is obtained for Cs2Te0.75Ti0.25I6. The calculated results indicate that all the structures are ductile materials except for Cs2Te0.50Ti0.50I6. Our results also show that these materials possess large absorption coefficients in the visible light region. Our work can provide a route to explore stable, environmentally friendly and high-efficiency light absorbers for use in optoelectronic applications.

Cu2MgO3 Electronic and Magnetic Properties – a DFT Study

AbstractWe investigate the properties of Guggenite‐α Cu2MgO3, which has an experimentally measured energy gap of approximately 1 eV. The band gap of Cu2MgO3, which is in the solar spectrum range makes it a potential candidate for photovoltaic applications. We calculate with PBE+U and LDA+U, and the SCAN functionals, the structure, formation energy and electronic structure of Cu2MgO3 in its anti‐ferromagnetic ground state and in the ferromagnetic phase. Finally we discuss the formation energy and band gap dependence on the U‐J Hubbard potential and compare our results to experiment.

Electronic and Optical Properties of Organic–Inorganic MASn1−xGexI3 Perovskites: A First-Principles Study

In recent years, the search of lead-free perovskites have been investigated to obtain better structural stability and photovoltaic performance compared with the corresponding lead-based hybrid perovskites. In this work, we calculated the structural stabilities, electronic and optical properites of the mixed MASn1−xGexI3 perovskites using the HSE06 functional. The results indicate that our predicted mixed Sn–Ge perovskites are stable, but they are weaken than that of MASnI3. The calculated results show that these mixed perovskites possess direct band gaps from 1.22 to 1.74 eV. The calculated band gaps of the mixed Sn–Ge perovskites are in the suitable ranges for single-junction solar cell. The mixed MASn1−xGexI3 perovskites also possess strong optical absorption abilities in the visible light region. Based on our calculated results, these mixed Sn–Ge perovskites are potential candidates for photovoltaic applications. We expect that this work can provide a insight for further research on lead-free perovskite solar cells.

Carrier Tuning in ZnSnN2 by Forming Amorphous and Microcrystalline Phases.

ZnSnN2 (ZTN), an earth-abundant element semiconductor, is a potential candidate for photovoltaic applications. However, the excessively high n-type carrier concentration caused by intrinsic defects hinders its progress. In this work, a series of Zn1± xSnN2 thin films are fabricated by RF-magnetron sputtering deposition. The zinc-rich composition is found to promote the crystallization of ZTN. As a main source of n-type carriers in the zinc-rich thin films, the interstitial Zn dominates the change of carrier concentration with an increase in the Zn/Sn ratio. Near the stoichiometric ratio, amorphous ZTN (a-ZTN) thin films are fabricated, and the n-type carrier concentration is suppressed to 1016 cm-3. With an increase in the Zn/Sn ratio from 0.9 to 1.3, the n-type carrier concentration can be tuned in the range 1016-1019 cm-3, accompanied by the phase-transition from a-ZTN to microcrystalline ZTN (μc-ZTN). For the a-ZTN thin film, the carrier mobility reaches up to 7 cm2 V-1 s-1, and the photoresponse covers almost the whole visible band. The above properties demonstrate that a-ZTN and μc-ZTN are potential candidates for photovoltaic applications.

Sn doping induced intermediate band in CuGaS2

As an intermediate band material, the dynamical and phase stability and optoelectronic properties of Sn doped CuGaS2 are systematically investigated, and suggest that CuGaS2 that is moderately doped with Sn can be a potential candidate for photovoltaic applications.

Solution processible Cu2SnS3 thin films for cost effective photovoltaics: Characterization

Thin films of Cu2SnS3 (CTS) were deposited by the facile solution processed sol–gel route followed by a low-temperature annealing. The Cu–Sn-thiourea complex formation was analysed using Fourier Transform Infrared spectrophotometer (FTIR). The various phase transformations and the deposition temperature range for the initial precursor solution was determined using Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). X-Ray Diffraction (XRD) studies revealed the tetragonal phase formation of the CTS annealed films. Raman spectroscopy studies further confirmed the tetragonal phase formation and the absence of any deterioratory secondary phases. The morphological investigations and compositional analysis of the films were determined using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) respectively. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 1.3 nm. The absorption coefficient was found to be 104 cm−1 and bandgap 1.3 eV which qualifies CTS to be a potential candidate for photovoltaic applications. The refractive index, extinction coefficient and relative permittivity of the film were measured by Spectroscopic ellipsometry. Hall effect measurements, indicated the p type nature of the films with a hole concentration of 2 × 1018 cm−3, electrical conductivity of 9 S/cm and a hole mobility of 29 cm2/V. The properties of CTS as deduced from the current study, present CTS as a potential absorber layer material for thin film solar cells.

Annealing effects on physical properties of doped CdTe thin films for photovoltaic applications

Polycrystalline Cadmium Telluride (CdTe) thin films were prepared on glass substrates by thermal evaporation at the chamber ambient temperature and then annealed for an hour in vacuum ~1×10−5mbar at 400°C. These annealed thin films were doped with copper (Cu) via ion exchange by immersing these films in Cu (NO3)2 solution (1g/1000ml) for 20min. Further these films were again annealed at different temperatures for better diffusion of dopant species. The physical properties of an as doped sample and samples annealed at different temperatures after doping were determined by using energy dispersive x-ray analysis (EDX), x-ray diffraction (XRD), Raman spectroscopy, transmission spectra analysis, photoconductivity response and hot probe for conductivity type. The optical band gap of these thermally evaporated Cu doped CdTe thin films was determined from the transmission spectra and was found to be in the range 1.42–1.75eV. The direct energy band gap was found annealing temperatures dependent. The absorption coefficient was >104cm−1 for incident photons having energy greater than the band gap energy. Optical density was observed also dependent on postdoping annealing temperature. All samples were found having p-type conductivity. These films are strong potential candidates for photovoltaic applications like solar cells.

Modulating triphenylamine-based organic dyes for their potential application in dye-sensitized solar cells: a first principle theoretical study.

By using computational methodologies based on time dependent density functional theory (TDDFT) we study the opto-electronic properties of three types of triphenylamine (TPA)-based dyes, namely TPA-TBT-1, TPA-DBT-1, and TPA-BT-1, and these are proposed as potential candidates for photovoltaic applications. Energy band modulation has been performed by functionalizing these dyes with different electron donating and electron withdrawing groups. Photoelectron spectra and photovoltaic properties of the dyes have been investigated by a combination of DFT and TDDFT approaches. Based on the optimized molecular geometry, relative position of the frontier energy levels, and the absorption maximum of the dyes we propose some dyes offering good photovoltaic performance. At the same time, these results provide a direction for optimizing the composition of dye-metal surface nanodevices for fabricating dye-sensitized solar cells (DSSCs).