Lead-free Solar Cells Research Articles

Synergistic Modulation of Sn2+ Oxidation and Perovskite Crystallization Induced by 4-Hydroxypyridine for Stable Lead-Free Solar Cells.

Tin perovskites present promising alternatives to lead perovskites, offering comparable optoelectronic properties alongside environmentally friendly characteristics. However, the rapid crystallization and easy oxidation of Sn2+ lead to poor film quality, further constraining the device performance. Here, 4-hydroxypyridine (4-HP) is introduced into the tin perovskite precursor for fabrication of high-quality tin perovskite films. 4-HP could modulate the colloidal size of prenucleation perovskite clusters in the precursor, thus inducing fast nucleation and retarding the crystal growth rate of tin perovskite through the formation of chemical interaction between nitrogen of pyridine and Sn2+ ions. Furthermore, the hydroxyl group on the pyridine ring contributes to suppressing the oxidation of Sn2+. As a result, the power conversion efficiency (PCE) of the devices based on 4-HP increases up to 11.3%. The stability of the unencapsulated devices shows significant improvement, retaining 100% of their initial PCEs after 2000 h of storage in N2 with 50-100 ppm of O2. This research presents a novel approach to the synchronized regulation of tin perovskite crystallization and the suppression of Sn2+ oxidation.

Performance optimization of a novel perovskite solar cell with power conversion efficiency exceeding 37% based on methylammonium tin iodide

The development of highly efficient lead-free solar cells is essential for sustainable energy production in the face of depleting fossil fuel resources and the negative effects of climate change. Perovskite solar cells (PSCs) containing lead pose considerable environmental and public health hazards, in addition to thermal stability and longevity challenges. Here, a novel lead-free solar cell design of the configuration, ITO/PC61BM/CH3NH3SnI3/PEDOT:PSS/Mo, is investigated for improved light harvesting capabilities, enhanced device performance, and better operational efficiency under various temperature conditions. The optimal thickness of the light-absorbing layer, CH3NH3SnI3, was found to be 1000 nm for maximum quantum efficiency (QE). Further, the temperature tolerance of the solar cell was evaluated using Mott-Schottky (MS) capacitance analysis and showed that the model cell retains about 95% of its power at 400 K, demonstrating excellent thermal stability and robust performance. The solar cell also shows promising electrical output parameters, including a short-circuit current density (Jsc) of 34.84 mA/cm², open-circuit voltage (Voc) of 1.5226 V, Fill factor (FF) of 71.04%, and an impressive power conversion efficiency (PCE) of 37.66% at 300 K. The effect of buffer layers such as CdS, ZnS, ZnSe, and V2O5 on the electrical outcomes of the model cell structure has been critically examined. Additionally, parasitic resistances and doping characteristics on the operational performance of the cell have been explored in detail. This work therefore, provides remarkable insights in the field of solar energy harvesting, offering potential sustainable energy generation solutions, supporting de-carbonization of the environment and climate change mitigation efforts towards an energy sustainable future.

High-Stable Lead-Free Solar Cells Achieved by Surface Reconstruction of Quasi-2D Tin-Based Perovskites.

Tin halide perovskites are an appealingalternative to lead perovskites. However, owing to the lower redox potential of Sn(II)/Sn(IV), particularly under the presence of oxygen and water, the accumulation of Sn(IV) at the surface layer will negatively impact the device's performance and stability. To this end, this work has introduced a novel multifunctional molecule, 1,4-phenyldimethylammonium dibromide diamine (phDMADBr), to form a protective layer on the surface of Sn-based perovskite films. Strong interactions between phDMADBr and the perovskite surface improve electron transfer, passivating uncoordinated Sn(II), and fortify against water and oxygen. In situ grazing incidence wide-angle X-ray scattering (GIWAXS) analysis confirms the enhanced thermal stability of the quasi-2D phase, and hence the overall enhanced stability of the perovskite. Long-term stability in devices is achieved, retaining over 90% of the original efficiency for more than 200 hours in a 10% RH moisture N2 environment. These findings propose a new approach to enhance the operational stability of Sn-based perovskite devices, offering a strategy in advancing lead-free optoelectronic applications.

Green-based modifiable CaZnBr4 for solar cells application

Future revolution in photovoltaics will be hinged mainly on cost, health implication, and material stability and performance. Based on these criteria, lead-based inorganic photovoltaics, organic–inorganic hybrid, and silicon photovoltaics are screened-out. According to the literature, the lead-free inorganic perovskite solar cell is favorably disposed to cost and safe-health. However, the simultaneous solution to material stability, high defect density, and low power conversion efficiency (PCE) still remains a mystery that has not been solved. This research proposed the green-based modifiable CaZnBr4 as a potential candidate for lead-free solar cell application based on the principle of A-site cation with green-based additive incorporation. The green-based additive was obtained from Kola Nitida, Carica Papaya, Ficus Exasperata, and Musa paradisiaca. The elemental characterization of the green-based additives was performed using X-ray fluorescence spectroscopy (XRF). The optical, crystalline, and electronic properties were characterized using ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffractometry, Quantum Espresso, scanning electron microscopy and SCAPS-1D. The green-base-modified CaZnBr4 showed significant PCE improvement by 3% with significant film and crystallinity formation. The stressed state of the parent compound CaZnBr4 shows that it may be better suited for thermovoltaics application. It is recommended that better results could be obtained when different synthetic routes and green-based additives are used to initiate the defect passivation protocols.

Pressure induced electronic and optical responses of vacancy-ordered double perovskites Cs2BX6 (B = Zr, Pd, Sn; X = Cl, Br, I)

Abstract Due to the toxicity and instability of lead-containing perovskites, high-performance lead-free perovskite attracts considerable attention. Lead-free vacancy-ordered double perovskites (VODP) emerge as environmentally friendly and efficient solutions as lead-containing solar cell substitutes. In this study, electronic properties of vacancy-ordered double perovskites Cs2BX6 (B = Zr, Pd, Sn; X = Cl, Br, I) under high pressure are investigated using first-principles methods. Semiconductors with bandgaps between 1.1 to 1.6 eV are considered for application. Our results show Cs2PdCl6 giving 1.60 and 1.32 eV bandgaps at 5 and 10 GPa, Cs2PdBr6 yielding 1.22 eV at ambient pressure, Cs2SnBr6 having 1.31 and 1.03 eV bandgap at 5 and 10 GPa, and Cs2ZrI6 showing 1.52 and 1.28 eV bandgap at 15 and 20 GPa. Furthermore, we considered the absorption coefficient and spectrum to ensure the materials’ optical performance. Cs2PdCl6, Cs2PdBr6, and Cs2ZrI6 display competent absorbance in the visible light range and proved these vacancy-ordered double perovskites as promising lead-free solar cell materials.

Improving the efficiency of a FTO/PCBM/Cs2AgBiBr6/NiOx/Au lead-free double perovskite solar cell using numerical simulation through optimizing the absorption layer thickness and work function of electrodes

Lead-free perovskite solar cells are proposed to reduce environmental toxicity. However, the efficiency of these solar cells is significantly lower than that of those based on lead. The maximum Photo Conversion Efficiency(PCE) reported experimentally for lead free solar cells is 6.37%, which is significantly lower than that of lead-based solar cells. Attempts have been made to improve the PCE of lead-free solar cells using numerical simulations in order to build a lead-free solar cell with the highest efficiency attainable. Recently, a lead-free solar cell with the configuration ITO/SnO2/Cs2AgBiBr6/P3HT/Au and a maximum PCE of 11.69% was numerically investigated. In this study, we suggested a lead-free solar cell structure using FTO/PCBM/Cs2AgBiBr6/NiOx/Au configuration and showed that,when operated in the wavelength range 400–700 nm, a PCE of 15.49% with Jsc = 8.17 mA/cm2, Voc = 2.49 V and FF = 76.16% can be attained by optimizing the thickness of the absorption layer and the work function of the electrode. While in the same configuration the PCE can be increased to 21.92% when operated in the wavelength range of 350–750 nm.This investigation's findings can be used to manufacture more efficient and stable lead-free solar cells forfuturenon-hazardous environmental applications.

Numerical investigation of toxic free perovskite solar cells for achieving high efficiency

Increasing efficiency, simple and inexpensive fabrication process and flexibility nature of organic metal halide perovskite (PVK) based solar cell has fascinated the researchers around the globe. However, Lead, a poisonous substance in PVK solar cell causes various issues which directly or indirectly impact the environment as well as the health of living things. It prevents the commercialization of PVK based solar cell. To overcome this, a number of lead-free perovskite solar cell has been designed and fabricated. But the conversion efficiency is still not up to par because of intrinsic losses. In order to improve the efficiency, a thorough theoretical investigation is required that can reveal the cause behind these losses. In this study a special PVK material named methylammonium tin iodide (MASnI3) is used in simulation platform to design a highly efficient organic lead-free solar cell. This study focuses on the optimization of active layer thickness, working temperature, capacitance-voltage (C-V), and impedance and defect density, as they plays major roles in determining the performance of toxic free organic PVK solar cell. The study confirms an high efficiency (η) of 24.22% at the optimized condition. Such high efficiency with an optimized structure can open a door for the commercialization of lead free PVK based solar cell.

LARP-assisted synthesis of CsBi3I10 perovskite for efficient lead-free solar cells.

Bismuth-based perovskites are an important class of materials in the fabrication of lead-free perovskite solar cells. Bi-based Cs3Bi2I9 and CsBi3I10 perovskites are getting much attention due to their appropriate bandgap values of 2.05 eV and 1.77 eV, respectively. However, the device optimisation process plays a key role in controlling the film quality and the performance of perovskite solar cells. Hence, a new strategy to improve crystallization as well as the thin film quality is equally important to develop efficient perovskite solar cells. Herein, an attempt was made to prepare the Bi-based Cs3Bi2I9 and CsBi3I10 perovskites via the ligand-assisted re-precipitation approach (LARP). The physical, structural, and optical properties were investigated on perovskite films deposited by the solution process for solar cell applications. Cs3Bi2I9 and CsBi3I10-based perovskite-based solar cells were fabricated using the device architecture of ITO/NiO x /perovskite layer/PC61BM/BCP/Ag. The device fabricated with CsBi3I10 showed the best power conversion efficiency (PCE) of 2.3% with an improved fill factor (FF) of 69%, V OC of 0.79 V, and J SC of 4.2 mA cm-2 compared to the Cs3Bi2I9-based device which showed a PCE of 0.7% with a FF of 47%, V OC of 0.62 V and J SC of 2.4 mA cm-2.

Discovering layered lead-free perovskite solar absorbers via cation transmutation.

For the exploration of stable lead-free perovskites for solar cell applications, we propose a series of Dion-Jacobson (DJ) double perovskites with the formula BDA2MIMIIIX8 (BDA = 1,4-butanediamine) by substituting two Pb2+ in BDAPbI4 with an MI+ (Na+, K+, Rb+, Cu+, Ag+, and Au+) and MIII3+ (Bi3+, In3+, and Sb3+) pair. First-principles calculations demonstrated the thermal stabilities of all the proposed BDA2MIMIIIX8 perovskites. The electronic properties of BDA2MIMIIIX8 depend strongly on the choice of MI+ + MIII3+ and the structural archetype, and three out of 54 candidates with suitable solar band gaps and superior optoelectronic properties were selected for photovoltaic application. A highest theoretical maximal efficiency of over 31.6% is predicted for BDA2AuBiI8. The DJ-structure-induced interlayer interaction of apical I-I atoms is found to play a crucial role in promoting the optoelectronic performance of the selected candidates. This study provides a new concept for designing lead-free perovskites for efficient solar cells.

Designing an efficient lead-free perovskite solar cell with green-synthesized CuCrO2 and CeO2 as carrier transport materials.

With increased efficiency, simplicity in manufacturing, adaptability, and flexibility, solar cells constructed from organic metal halide perovskite (PVK) have recently attained great eminence. Lead, a poisonous substance, present in a conventional PVK impacts the environment and prevents commercialization. To deal with this issue, a number of toxicity-free PVK-constructed solar cells have been suggested. Nevertheless, inherent losses mean the efficiency conversion accomplished from these devices is inadequate. Therefore, a thorough theoretical investigation is indispensable for comprehending the losses to improve efficiency. The findings of a unique modelling method for organic lead-free solar cells, namely methylammonium tin iodide (MASnI3), are investigated to reach the maximum practical efficiencies. The layer pertinent to MASnI3 was constructed as a sandwich between a bio-synthesized electron transport layer (ETL) of CeO2 and a hole transport layer (HTL) of CuCrO2 in the designed perovskite solar cells (PSCs). In this study, the use of algae-synthesized Au in the back contacts has been proposed. To obtain the maximum performance, the devices are further analyzed and optimized for active layer thickness, working temperature, total and interface defect density analysis, impedance analysis (Z'-Z), and capacitance-voltage (C-V), respectively. An optimal conversion efficiency of 26.60% has been attained for an MASnI3-constructed PSC. The study findings may open the door to a lead-free PSC through improved conversion efficiencies.

Dopamine Hydrochloride-Assisted Synergistic Modulation of Perovskite Crystallization and Sn2+ Oxidation for Efficient and Stable Lead-free Solar Cells.

Tin perovskites have received great concern in solar cell research owing to their favorable optoelectronic performance and environmental friendliness. However, due to their poor crystallization and easy oxidation, the performance improvement for tin-based perovskite solar cells (TPSCs) is rather challenging. Herein, reductive 3-hydroxytyramine hydrochloride (DACl) with NH2·HCl and phenol groups as co-additives with SnF2 is added into the precursor to modulate perovskite crystallization and inhibit Sn2+ oxidation for high-performance TPSCs. The Lewis base group of NH2 HCl in DACl could bind to perovskite lattices to modulate the crystallization with suppressed defects in the bulk and grain boundary, whereas reductive phenol groups effectively constrain the Sn2+ oxidation. Moreover, the undissociated DACl decreases the supersaturated concentration of tin perovskite solution and creates a pre-nucleation site for rapid nucleation to further regulate crystallization. Consequently, the DACl-derived TPSCs achieve a high power-conversion efficiency (PCE) that reaches up to 11%. More impressively, the device remains at 84% of the initial PCE after full-sun illumination in N2 over 600 h without being encapsulated. This DACl-based synergistic modulation of a lead-free perovskite demonstrates a feasible approach using one molecule with different functional groups to manipulate crystallization, Sn2+ oxidation, and defect reparation of tin perovskite films, providing a critical guideline for constructing high-quality perovskites by multifunctional additives with high photovoltaic performance.

Sb2Se3 as an HTL for Mo/Sb2Se3/Cs2TiF6/TiO2 solar structure: performance evaluation with SCAPS-1D

Perovskite-based solar cells (PSCs) have recently gained much attention due to their distinctive optical and electrical properties. Cesium titanium fluoride (Cs2TiF6) is an example of lead-free perovskite absorber material with a bandgap of 1.9 eV, making it suitable for a solar device. However, the high cost of the hole transport material (HTM) and other considerations prevent their commercial production. Antimony selenide (Sb2Se3) is well suited for HTM as it is low-cost material with a tunable bandgap. The work presents the TiO2/Cs2TiF6/Sb2Se3-based solar cell performance using SCAPS-1D simulation software. The effect of all the active layer thicknesses, defect density, hole-electron mobility, and temperature on the device is also simulated. I–V, C–V, and QE curves and energy band diagrams show the photovoltaic device's excellent performance. The outputs are competent enough with an efficiency of 22.10 % when Sb2Se3 is used as a hole transport layer (HTL) in the device architecture. The results suggest that the lead-free solar cell is a promising future option for the solar cell community regarding environmental friendliness and high efficiency.

Evaluating the performance of Cs2PtI6−xBrx for photovoltaic and photocatalytic applications using first-principles study and SCAPS-1D simulation

All inorganic free-lead halide double perovskites are attractive materials in solar energy harvesting applications. In this study, density functional theory calculations have been used to predict the structures, band structures, and density of states of Cs2PtI6−xBrx with (x = 0, 2, 4, and 6). The optical properties (reflectivity, refractive index, absorption, dielectric function, conductivity, and loss function) of these materials have been predicted and discussed. The band edges calculations showed that the Cs2PtI6−xBrx may be an efficient visible-light photocatalyst for water splitting and CO2 reduction. The calculated bandgap value of Cs2PtI6 exhibited a great match with the reported experimental values. It has been seen that increasing the doping content of Br− in Cs2PtI6−xBrx (x = 0, 2, 4, and 6) increases the bandgaps from 1.4 eV to 2.6 eV and can be applied in single junction and tandem solar cells. Using Solar Cell Capacitance Simulator (SCAPS), a 1D device modelling has been performed on Cs2PtI6 inorganic lead-free solar cells. For the fully inorganic device, the effect of replacing organic hole transport materials (HTL) and electron transport materials (ETL) with inorganic ones is investigated while keeping high efficiencies and stabilities of solar cell devices. From the obtained results, it was found that WS2 as ETL and Cu2O as HTL were the most suitable materials compared to the others. Further investigation studies are performed on the effect of changing metal back contact work function, absorber layer thickness, doping density, and defect density on the power conversion efficiency (PCE) of the solar cell. The optimized suggested structure (FTO/WS2/Cs2PtI6/Cu2O/Carbon) obtained a PCE of 17.2% under AM1.5 solar illumination.

Manufacture of High-Efficiency and Stable Lead-Free Solar Cells through Antisolvent Quenching Engineering.

Antisolvent quenching has shown to significantly enhance several perovskite films used in solar cells; however, no studies have been conducted on its impact on MASnI3. Here, we investigated the role that different antisolvents, i.e., diethyl ether, toluene, and chlorobenzene, have on the growth of MASnI3 films. The crystallinity, morphology, topography, and optical properties of the obtained thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) measurements, and UV–visible spectroscopy. The impact of the different antisolvent treatments was evaluated based on the surface homogeneity as well as the structure of the MASnI3 thin films. In addition, thermal annealing was optimized to control the crystallization process. The applied antisolvent was modified to better manage the supersaturation process. The obtained results support the use of chlorobenzene and toluene to reduce pinholes and increase the grain size. Toluene was found to further improve the morphology and stability of thin films, as it showed less degradation after four weeks under dark with 60% humidity. Furthermore, we performed a simulation using SCAPS-1D software to observe the effect of these antisolvents on the performance of MASnI3-based solar cells. We also produced the device FTO/TiO2/MASnI3/Spiro-OMeTAD/Au, obtaining a remarkable photoconversion efficiency (PCE) improvement of 5.11% when using the MASnI3 device treated with chlorobenzene. A PCE improvement of 9.44% was obtained for the MASnI3 device treated with toluene, which also showed better stability. Our results support antisolvent quenching as a reproducible method to improve perovskite devices under ambient conditions.

Synergistic effects of morphological control and enhanced charge collection enable efficient and stable lead-free CsBi3I10 thin film solar cells

A fabrication technique and additive approach to modulate CsBi3I10 morphology and increase charge collection yield is reported. New insights into the crystallization mechanism are provided, and the developed strategies are applicable towards lead-free solar cells.

Improved lead-free solar cells lay groundwork for environmentally friendly designs

The power conversion efficiency of lead-free inorganic perovskite solar cells is improved by additive engineering.

Crystal structure, computational study, optical and vibrational properties of a new luminescent material based on bismuth(III): (C10H28N4)[Bi2Cl10

Development of new Bi-based perovskites with various structures offers considerable potential for lead-free solar cells and other optoelectronic devices as they retain the high-performing properties of halide perovskites with high power conversion efficiency and improved long-term and environmental device stability. This work addresses the study of a new chlorobismuthate(III) hybrid compound with the chemical formula (C10H28N4)[Bi2Cl10], prepared at room temperature by the slow evaporation method. The resulting crystals were investigated using Single Crystal X-ray diffraction, which gave an accurate crystal structure determination that allows searching the role played by intermolecular contacts in the self-assembly of the crystal structure using Hirshfeld surface analysis. The compound was additionally characterized using FTIR and Raman spectroscopies correlated by Ab-initio calculations at different levels of theory. The optical study supports the strong absorption of the compound in the visible region showing its luminescent character with emission peaks falling in the blue and near green regions. Natural bond orbital (NBO) calculations suggest a high stability of the new hybrid material attributed to energetically electronic transitions of [Bi2Cl10]4- anion that probably support its interesting optical properties. The shifting of stretching modes assigned to N–H groups belonging to the piperazine ring of the compound toward lower wavenumbers confirms well the interactions observed by NBO calculations between Cl atoms of the anion with these groups. The Raman bands detected below 300 cm−1 were found in perfect agreement with the characteristic of isolated Bi2Cl10 anion, made up of two [BiCl52−] units. The TG-DTA analysis revealed the high stability of the compound and its decomposition at 280°С. Frontier orbital studies showed the gap values of the new hybrid and its low reactivity. Probably, the inert mapped molecular electrostatic potential (MEP) surface predicted on the new material could support its high stability and low reactivity. The complete assignments for this compound in comparison with the organic and inorganic species are also presented. HF/Lanl2dz calculations in n-hexane solution have evidenced an increase in the reactivity of the hybrid and changes of positions and intensities of IR bands, attributed to NH3, NH and CH2 stretching modes, as a consequence of interactions of the anion with those groups belonging to the cation.

Dual-Site Compositional Engineering of Bismuth-Based Halide Perovskites for Stable and Efficient Lead-free Solar Cells

Dual-Site Compositional Engineering of Bismuth-Based Halide Perovskites for Stable and Efficient Lead-free Solar Cells

Fundamentals of tin iodide perovskites: a promising route to highly efficient, lead-free solar cells

Chemical potentialμehand radiative lifetimeτradbehaviourvs.carrier densitynin FASnI3. They change dramatically with hole doping concentration, inducing large Burstein–Moss shift

Recent Progress in Fabrication of Antimony/Bismuth Chalcohalides for Lead-Free Solar Cell Applications.

Despite their comparable performance to commercial solar systems, lead-based perovskite (Pb-perovskite) solar cells exhibit limitations including Pb toxicity and instability for industrial applications. To address these issues, two types of Pb-free materials have been proposed as alternatives to Pb-perovskite: perovskite-based and non-perovskite-based materials. In this review, we summarize the recent progress on solar cells based on antimony/bismuth (Sb/Bi) chalcohalides, representing Sb/Bi non-perovskite semiconductors containing chalcogenides and halides. Two types of ternary and quaternary chalcohalides are described, with their classification predicated on the fabrication method. We also highlight their utility as interfacial layers for improving other solar cells. This review provides clues for improving the performances of devices and design of multifunctional solar systems.