Interstitial Doping Research Articles

Theoretical approaches to defect mechanisms and transport properties of compounds used for electrodes and solid-state electrolytes in alkali-ion batteries.

The transition from fossil fuels to cleaner energies employing different renewable sources constitutes one of the primary worldwide challenges. The search for appropriate solutions is becoming more urgent in view of the severe consequences of climate change. As for a perspective, stationary energy storage, alkali-ion batteries and hybrid supercapacitors are, among others, considered as efficient and affordable solutions. Alkali-ion batteries have proved to be the most investigated products in the past decade including optimizations for cost, energy density and safety. In this Perspective, a computational approach and its applicability in the inverse material design are presented. This approach includes density functional theory calculations, force field-based determinations and both static and molecular dynamics simulations. As for an illustration, the main properties of a selected series of battery materials, including oxides and sulfides Li2SiO3, Li2SnO3, SrSnO3, and A2B6X13 (A = Li+, Na+, K+; B = Ti4+, Sn4+; X = O2-, S2-), and mixed halide antiperovskite A3OX (A = Li+, Na+; X = Cl-, Br-) are explored in depth using these theoretical approaches. Doping strategies, new dopant incorporation mechanism, treatment with alkali insertion/de-insertion cycle in electrodes, transport properties, as well as thermodynamic stability, are discussed. Theoretical approaches reveal that the oxygen-sulfur exchange in alkali hexatitanates and hexastannates induces remarkable improvement of the required properties for electrode and electrolyte materials. In addition, doping of Li2SiO3 with low Na-concentration enhances the room temperature Li-diffusivity by a reduction of the activation energy. The effects of transition-metal and divalent dopants on the defect chemistry and transport properties of Li2SnO3 are also disclosed. The interstitial trivalent doping mechanism is a friendly synthesis strategy to improve the large-scale diffusion in Li2SnO3. The potential of SrSnO3 as an anode in alkali-ion batteries, and the influence of a particular grain boundary in nanocrystalline antiperovskite A3OX are also revealed by using advanced atomistic simulations. The computational approaches described here provide us with a convenient tool for the determination of the properties of battery materials with high accuracy and for the prediction of characteristics of a new generation of alkali battery materials that could be used in improved technologies.

Ion beam irradiation: Novel approach for preparation of Ag coated N doped nanocrystalline anatase TiO2 films

Herein, a novel approach of ion beam irradiation (nitrogen beam dose ∼ 1013 ions/cm2, 40 keV for 30 min in ultra-high vacuum conditions) is explored for the preparation of nanocrystalline anatase TiO2 modified with nitrogen (N) and silver (Ag). The prepared materials characterized using XRD, Raman, UV–Visible spectroscopy, EIS and wettability techniques. The structural-optical studies revealed the interstitial and/or substitutional doping of N in O-Ti-O matrix supported by Williamson-Hall lattice strain values and dispersion of Ago particles at the TiO2 surface. Raman spectra confirmed the crystallization of anatase TiO2 wherein red shifting-broadening of Raman active modes are due to the phonon confinement and structural defects due to favored substitutional N3– doping in TiO2 lattice. The higher values of Z′, Z″, and RCT in Nyquist plots and the blue shift of ωmax in Bode plots for irradiated films further supported the substitutional doping of N rather than the interstitial one.

Effects of Ni dopant on morphology, crystal and electronic structure, electrical properties of sodium trititanate

Sodium trititanate doped with nickel in different amounts for the first time have been prepared through one-step hydrothermal synthesis. Both cation substitution and interstitial doping are realized with a formation of oxygen-deficient Na2+xTi3–yNix+yO7–δ solid solutions. The Ni-doping results in the sodium trititanate unit cell expansion. The morphology was found to be evolved with increasing dopant concentration from nanotubes to nanosheets. The specific surface area ranges from 121 to 78 m2 g–1 depending on dopant content. With nickel-doping, the bandgap narrowed from 3.45 up to 2.94eV. The conductivity of sodium trititanate increases in 3–6 fold after the nickel incorporation. A deviation from the Arrhenius temperature dependence of the conductivity is observed above 350 K indicating that mixed ionic-electronic conductors based on Ni-doped sodium trititanate are formed. This paper contributes to the advance understanding doping principles and effects for Na2Ti3O7-based materials, which are currently under consideration.

Suppressing ion migration in metal halide perovskite via interstitial doping with a trace amount of multivalent cations.

Cations with suitable sizes to occupy an interstitial site of perovskite crystals have been widely used to inhibit ion migration and promote the performance and stability of perovskite optoelectronics. However, such interstitial doping inevitably leads to lattice microstrain that impairs the long-range ordering and stability of the crystals, causing a sacrificial trade-off. Here, we unravel the evident influence of the valence states of the interstitial cations on their efficacy to suppress the ion migration. Incorporation of a trivalent neodymium cation (Nd3+) effectively mitigates the ion migration in the perovskite lattice with a reduced dosage (0.08%) compared to a widely used monovalent cation dopant (Na+, 0.45%). The photovoltaic performances and operational stability of the prototypical perovskite solar cells are enhanced with a trace amount of Nd3+ doping while minimizing the sacrificial trade-off.

Ceftriaxone sodium degradation by carbon quantum dots (CQDs)-decorated C-doped α-Bi2O3 nanorods

A novel carbon quantum dots decorated C-doped α-Bi2O3 photocatalyst (CBO/CQDs) was synthesized by solvothermal method. The synergistic effect of adsorption and photocatalysis highly improved contaminants removal efficiencies. The ceftriaxone sodium degradation rate constant (k) of CBO/CQDs was 11.4 and 3.2 times that of pure α-Bi2O3 and C-doped α-Bi2O3, respectively. The interstitial carbon doping generated localized states above the valence band, which enhanced the utilization of visible light and facilitated the separation of photogenerated electrons and holes; the loading of CQDs improved the charge carrier separation and extended the visible light response; the reduced particle size of CBO/CQDs accelerated the migration of photogenerated carriers. The •O2− and h+ were identified as the dominant reactive species in ceftriaxone sodium degradation, and the key role of •O2− was further investigated by NBT transformation experiments. The Fukui index was applied to ascertain the molecular bonds of ceftriaxone sodium susceptible to radical attack, and intermediates analysis was conducted to explore the possible degradation pathways. The toxicity evaluation revealed that some degradation intermediates possessed high toxicity, thus the contaminants require sufficient mineralization to ensure safe discharge. The present study makes new insights into synchronous carbon dopping and CQDs decoration on modification of α-Bi2O3, which provides references for future studies.

Influence of oxygen and nitrogen doping on the structure and magnetic properties of CoNi alloy: First principle calculations

We have studied the effects of oxygen and nitrogen doping as interstitial defects on the structure and magnetic properties of CoNi alloy using the first principle density functional theory, where we include the orbital-spin interaction in the calculations. Our calculations reveal that the CoNi:ONi in the L10-structure has a large enhancement in the saturation magnetization (Ms) and a small reduction in the magnetic crystalline anisotropy (MCA). For CoNi:OCo, we found a small reduction in Ms and MCA. However, for CoNi:NCo and CoNi:NNi there is always a reduction in Ms and MCA. Therefore, the first alloy could be suitable for permanent magnets. A detailed analysis of other parameters, such as the magnetic hardness parameter (κ), optimum supercell parameters, anisotropy field (Ha), and formation energy (Efor) is presented. The interstitial oxygen doping enhances the magnetic properties.

Dense dislocations enable high-performance PbSe thermoelectric at low-medium temperatures

PbSe-based thermoelectric materials exhibit promising ZT values at medium temperature, but its near-room-temperature thermoelectric properties are overlooked, thus restricting its average ZT (ZTave) value at low-medium temperatures. Here, a high ZTave of 0.90 at low temperature (300–573 K) is reported in n-type PbSe-based thermoelectric material (Pb1.02Se0.72Te0.20S0.08−0.3%Cu), resulting in a large ZTave of 0.96 at low-medium temperatures (300–773 K). This high thermoelectric performance stems from its ultralow lattice thermal conductivity caused by dense dislocations through heavy Te/S alloying and Cu interstitial doping. The dislocation density evaluated by modified Williamson-Hall method reaches up to 5.4 × 1016 m−2 in Pb1.02Se0.72Te0.20S0.08−0.3%Cu. Moreover, the microstructure observation further uncloses two kinds of dislocations, namely screw and edge dislocations, with several to hundreds of nanometers scale in length. These dislocations in lattice can strongly intensify phonon scattering to minimize the lattice thermal conductivity and simultaneously maintain high carrier transport. As a result, with the reduced lattice thermal conductivity and optimized power factor in Pb1.02Se0.72Te0.20S0.08−0.3%Cu, its near-room-temperature thermoelectric performance is largely enhanced and exceeds previous PbSe-based thermoelectric materials.

Electrodeposition of Rhenium Sandwich Structures and the Superconducting Transition Behavior

Superconductors with enhanced superconducting critical temperatures (Tc) above the boiling point of liquid helium (4.2 K) are of interest for interconnections in superconducting quantum computing systems to avoid ohmic heating[1]. Crystalline Re in bulk is a type-I superconductor with a Tc of about 1.7K[2]. An elevated Tc up to about 6K in electrodeposited amorphous Re has been reported[3]. In addition, various elevation in Tc has also been reported for Re film under shear strain[4] or doped with foreign elements such as Tungsten (W), Osmium (Os), and Carbon (C)[5, 6].This work aims to test a hypothesis that the Tc of electrodeposited Re films can be tuned using compressive and tensile strains on the Re films generated with thermal expansions difference. Figure 1 shows a diagram of the strains on Re film sandwiched between metals with different coefficients of thermal expansions (CTEs) when the temperature is lowered. For example, Cu has a higher CTE than Re and Cr has a slightly lower CTE than Re. Such sandwich structures are prepared at room temperature using electrochemical deposition. The DC resistance measurements at cryogenic temperatures confirmed that the superconducting transition for the Re films sandwiched between Cu occurs at a lower temperature than the Re film alone. On the other hand, when Cr is used, the sandwiched Re structure shows a slightly enhanced superconducting critical temperature. The effect of thermal annealing i.e., the recrystallization of electrodeposited Re films at an elevated temperature, and electrochemical behavior of Re, Cr, and Cu electrodeposition will be discussed in the talk. References Radenbaugh, R., Refrigeration for superconductors. Proceedings of the IEEE, 2004. 92(10): p. 1719-1734.Hulm, J.K., Superconductivity of Pure Metallic Rhenium. Physical Review, 1954. 94(5): p. 1390-1391.Pappas, D.P., et al., Enhanced superconducting transition temperature in electroplated rhenium. Applied Physics Letters, 2018. 112(18): p. 182601.Mito, M., et al., Large enhancement of superconducting transition temperature in single-element superconducting rhenium by shear strain. Scientific Reports, 2016. 6(1): p. 36337.Chu, C.W., W.L. McMillan, and H.L. Luo, Superconductivity of Re-Os, Re-Ru, Ru-Os, and Re-W hcp Alloy Systems and Slightly Doped Re. Physical Review B, 1971. 3(11): p. 3757-3762.Zhu, Q., et al., Anisotropic lattice expansion and enhancement of superconductivity induced by interstitial carbon doping in Rhenium. Journal of Alloys and Compounds, 2021. 878: p. 160290. Figure 1

Basal Planes Unlocking and Interlayer Engineering Endows Proton Doped-MoO2.8F0.2 with Fast and Stable Magnesium Storage.

Molybdenum trioxide has served as a promising cathode material of rechargeable magnesium batteries (RMBs), because of its rich valence states and high theoretical capacity; yet, it still suffers from sluggish (de)intercalation kinetics and inreversible structure change for highly polarized Mg2+ in the interlayer and intralayer of structure. Herein, F- substitutional and H+ interstitial doping is proposed for α-MoO3 materials (denoted HMoOF) by the intralayer/interlayer engineering strategy to boost the performance of RMBs. F- substitutional doping generates molybdenum vacancies along the Mo-O-□ or Mo-F-□ configurations (where □ represents the cationic vacancy) for unlocking the inactive basal plane of the layered crystal structure, and it further accelerates Mg2+ diffusion along the b-axis. Interstitial-doped H+ can expand interlayer spacing for reducing Mg2+ energy barrier along the ac plane and serve as a "pillar" to stabilize the interlayer structure. Moreover, anion and cation dual doping trigger shallow impurity levels (acceptors levels and donor levels), which helps to easily acquire the electrons from the valence band and donate the electrons to the conduction band. Consequently, the HMoOF electrode exhibits a high reversible capacity (241 mA h g-1 at 0.1 A g-1), an excellent rate capability (137.4 mAh g-1 at 2 A g-1), and a long cycling stability (capacity retention of 98% after 800 cycles at 1 A g-1) in RMBs. This work affords meaningful insights in layered materials for developing high-kinetics and long-life RMBs.

Interfacial Catalysis Enabled Acetone Sensors Based on Rationally Designed Mesoporous Metal Oxides with Erbium‐Doped WO3 Framework

AbstractThe emerging combination of Internet of Things requires the development of intelligent gas sensor, and semiconductor gas sensors based on metal oxides have been widely applied in industrial production, environmental monitoring, and food safety. Although versatile nanomaterials have been exploited as gas sensitive materials, restricted gas sensing performance including sensitivity, selectivity and stability, is still the fatal problem of practical applications. Herein, inspired by heteratomic doping engineering, unique rare earth erbium (Er)‐doped mesoporous tungsten oxide (Er/mWO3) has been synthesized via one‐step collaborative coassembly strategy, and Er ion‐doped mWO3 exhibited peculiarly hexagonal mesostructure (P63/mmc), tunable specific surface area (58.1–78.3 m2 g–1), uniform mesoporous size and highly crystallized framework with heteroatomic pore wall doping. The introduction of Er can significantly adjust the micro/nano structure and band characteristics, and 1.5 wt% Er‐doped mWO3 displays superior acetone sensing performance, including high response values (107 for 50 ppm), rapid response–recovery dynamics (9/56 s), prominent acetone selectivity, low concentration detection (125 ppb), anti‐humidity property and excellent long‐term stability. Such an excellent sensing performance is mainly attributed to unique interfaces catalytic sites induced by heteroatom interstitial doping. This finding opens a door for the design of smart gas sensors for environmental monitoring and industrial safety.

Extraordinary thermoelectric performance, thermal stability and mechanical properties of n-type Mg3Sb1.5Bi0.5 through multi-dopants at interstitial site

Mg3Sb2-based thermoelectric materials have attracted much interest since the discovery of their excellent n-type thermoelectric performance with excess Mg content and proper dopant. Herein, we proposed a doping diagram for Mg3Sb2-based material in a binary parameters space of electronegativity difference and atomic radius difference of extrinsic elements with Mg atom. Based on this doping diagram, we designed a multiple interstitial doped TMx:Mg3Sb1.5Bi0.5 (TM = CrMnFeCoCu) material, and achieved a high dimensionless figure of merit value of 0.76 at room temperature and 1.83 at 500 °C, respectively. The multiple interstitial dopants significantly suppress the formation of Mg vacancy, which is of great importance in protecting the electrical transport channel and improving the thermal stability. Besides, the mechanical properties are also enhanced due to the random distribution of elements in the matrix, impeding the migration of dislocations. Our work verifies the benefits of maximized sub-lattice disordering through the multi-elements doping strategy in the Mg3Sb1.5Bi0.5 material.

Enhanced charge transfer and reaction kinetics of vanadium pentoxide for zinc storage via nitrogen interstitial doping

Rechargeable aqueous zinc-ion batteries (ZIBs) are the prospective substitution for lithium-ion batteries applied in large scale energy storage system due to their low-cost, environmentally friendliness, and high safety. However, the development of cathodes in aqueous ZIBs suffers from sluggish Zn2+ migration. Herein, nitrogen doped V2O5 is introduced to resolve the above problem. N-doping lowers the bandgap energy of V2O5 to improve its electronic conductivity, and weakens the forces between Zn2+ and V2O5 to fasten Zn2+ diffusion. Further density functional theory (DFT) calculation testifies that N-doping reduces diffusion energy barrier and changes Zn2+ diffusion pathway from the vertical interlayer diffusion to planer intralayer diffusion. Meanwhile, the structural stability of electrode material also benefits from the N-doping, which can prevent the interlayer V2O5 from gliding or exfoliation during cycling. Profiting from these merits, N-doping V2O5 exhibits the outstanding electrochemical properties, such as high rate capability (116.8 mAh/g at 6 A/g) and long cycling performance (3000 cycles at 10 A/g). Dynamics and post-cycling analyses reveal the high capacitive ratio and the stable N distribution in N-doped V2O5 during charging/discharging.

Pivotal Role of Intersite Hubbard Interactions in Fe-Doped α-MnO2

We present a first-principles investigation of the structural, electronic, and magnetic properties of the pristine and Fe-doped $\alpha$-MnO$_2$ using density-functional theory with extended Hubbard functionals. The onsite $U$ and intersite $V$ Hubbard parameters are determined from first principles and self-consistently using density-functional perturbation theory in the basis of L\"owdin-orthogonalized atomic orbitals. For the pristine $\alpha$-MnO$_2$ we find that the so-called C2-AFM spin configuration is the most energetically favorable, in agreement with the experimentally observed antiferromagnetic ground state. For the Fe-doped $\alpha$-MnO$_2$ two types of doping are considered: Fe insertion in the $2 \times 2$ tunnels and partial substitution of Fe for Mn. We find that the interstitial doping preserves the C2-AFM spin configuration of the host lattice only when both onsite $U$ and intersite $V$ Hubbard corrections are included, while for the substitutional doping the onsite Hubbard $U$ correction alone is able to preserve the C2-AFM spin configuration of the host lattice. The oxidation state of Fe is found to be $+2$ and $+4$ in the case of the interstitial and substitutional doping, respectively, while the oxidation state of Mn is $+4$ in both cases. This work paves the way for accurate studies of other MnO$_2$ polymorphs and complex transition-metal compounds when the localization of $3d$ electrons occurs in the presence of strong covalent interactions with ligands.

Lattice expansion enables interstitial doping to achieve a high average ZT in n‐type PbS

AbstractLead sulfide (PbS) presents large potential in thermoelectric application due to its earth‐abundant S element. However, its inferior average ZT (ZTave) value makes PbS less competitive with its analogs PbTe and PbSe. To promote its thermoelectric performance, this study implements strategies of continuous Se alloying and Cu interstitial doping to synergistically tune thermal and electrical transport properties in n‐type PbS. First, the lattice parameter of 5.93 Å in PbS is linearly expanded to 6.03 Å in PbS0.5Se0.5 with increasing Se alloying content. This expanded lattice in Se‐alloyed PbS not only intensifies phonon scattering but also facilitates the formation of Cu interstitials. Based on the PbS0.6Se0.4 content with the minimal lattice thermal conductivity, Cu interstitials are introduced to improve the electron density, thus boosting the peak power factor, from 3.88 μW cm−1 K−2 in PbS0.6Se0.4 to 20.58 μW cm−1 K−2 in PbS0.6Se0.4−1%Cu. Meanwhile, the lattice thermal conductivity in PbS0.6Se0.4−x%Cu (x = 0–2) is further suppressed due to the strong strain field caused by Cu interstitials. Finally, with the lowered thermal conductivity and high electrical transport properties, a peak ZT ~1.1 and ZTave ~0.82 can be achieved in PbS0.6Se0.4 − 1%Cu at 300–773K, which outperforms previously reported n‐type PbS.

Ion implanted substitutionally dispersed Au in TiO2 nanostructures for efficient and stable dye sensitized solar cells

Various optical and electrical properties of noble metal doped TiO2 nanomaterials are found to vary remarkably with change in concentration and nature of doping. In the present work, ion implantation technique has been employed for generating substitutional and interstitial Au doping in TiO2 nanoparticle-nanofiber (NP–NF) composites. Experimentally, the presence of Au at substitutional and interstitial sites of TiO2 was detected through X-ray photoelectron spectroscopy. Depth profiling of implanted Au ions confirmed the presence of Au upto 70 nm. From the theoretical simulations, it was realized that substitutional Au doping results in higher strain and lower band gap contrary to pristine TiO2 and interstitial Au doped TiO2. Finally, the Dye sensitized solar cell (DSSC) prepared with substitutional doping was found to be 23.9% more efficient than interstitial Au based DSSC owing to enhanced light harvesting, higher fermi level and minimal recombinations as corroborated from current density-voltage and electrochemical impedance spectroscopy studies.

Formation of interfacial P-Ni-P coordination to boost charge transfer of polymeric carbon nitride for enhanced photocatalytic activity of H2 evolution

Constructing composite semiconductor photocatalysts with intimate interfacial contact is crucial for efficient charge separation and surface reaction kinetics towards enhancing hydrogen evolution via photocatalytic water splitting. In this work, an in-situ interfacial P-Ni-P coordination strategy for band modulation and interfacial engineering of the Ni2P/P-PCN system is reported based on interstitial doping P and coupled Ni2P cocatalysts. As a non-noble metal composite catalyst, Ni2P/P-PCN displayed a photocatalytic hydrogen evolution rate (HER) of 1250 μmol h−1 g−1, which was 1.4 times higher than that of Pt/P-PCN. The experimental characterization and theoretical calculation results showed that P dopant atoms at the P-PCN interface were coupled with Ni2P via interfacial P-Ni-P bonds. These acted as electron bridges that provided electron transfer channels at the interface, which greatly improved the interfacial compatibility between P-PCN and Ni2P. Combinedly, these effects promoted the rapid separation and transfer of photogenerated carriers. Thus, Ni2P/P-PCN can potentially replace Pt as a noble-metal-free cocatalyst for efficient synergistic HER under visible light irradiation.

Effect of Li+ Doping on Photoelectric Properties of Double Perovskite Cs2SnI6: First Principles Calculation and Experimental Investigation

Double perovskite Cs2SnI6 and its doping products (with SnI2, SnF2 or organic lithium salts added) have been utilized as p-type hole transport materials for perovskite and dye-sensitized solar cells in many pieces of research, where the mechanism for producing p-type Cs2SnI6 is rarely reported. In this paper, the mechanism of forming p-type Li+ doped Cs2SnI6 was revealed by first-principles simulation. The simulation results show that Li+ entered the Cs2SnI6 lattice by interstitial doping to form strong interaction between Li+ and I−, resulting in the splitting of the α spin-orbital of I–p at the top of the valence band, with the intermediate energy levels created and the absorption edge redshifted. The experimental results confirmed that Li+ doping neither changed the crystal phase of Cs2SnI6, nor introduced impurities. The Hall effect test results of Li+ doped Cs2SnI6 thin film samples showed that Li+ doping transformed Cs2SnI6 into a p-type semiconductor, and substantially promoted its carrier mobility (356.6 cm2/Vs), making it an ideal hole transport material.

Site-Selective Nitrogen-Doped α-MnO2 for Catalytic Oxidation of Carcinogenic HCHO in Indoor Air

Developing high-efficiency formaldehyde (HCHO) catalytic oxidation catalysts is of significance and practicability for indoor air decontamination. It is generally considered that anionic doping is a traditional strategy to regulate the reaction activity of catalyst materials. However, one of the concerns worth exploring is the recognition of doping sites and their impact on catalytic performance. Herein, nitrogen atoms are successfully introduced into the MnO2 structure by high-temperature calcination with urea as the nitrogen source for the first time. By regulating the usage of urea, nitrogen atoms are selectively and successfully doped into the interstitial sites and substitutional sites. Furthermore, the effect of nitrogen-doped MnO2 on the catalytic oxidation of HCHO is studied in detail. Results indicate that nitrogen doping can promote the formation of oxygen vacancies, strengthen the activation of adsorbed O2, and enhance the adsorption of HCHO, which is conducive to catalytic decomposition of HCHO. Importantly, nitrogen doping at various doping sites has a considerable effect on catalytic decomposition activity. Although both interstitial and substitutional nitrogen doping can boost the decomposition performance of HCHO, the interstitial sites are the most suitable doping sites in the α-MnO2 lattice. The chemical environment around the interstitial sites is favorable for the creation of oxygen vacancies, as well as the adsorption/activation of HCHO and O2. Interstitial nitrogen doping can dramatically increase the HCHO catalytic activity of α-MnO2, and the complete catalytic decomposition temperature is reduced from 130 to 90 °C at the condition of GHSV = 90 L/gcat·h. This study provides a facile and effective method for site-selective nitrogen-doping and an in-depth understanding of its effect on catalytic activity.

Hydrogenated Cs2AgBiBr6 for significantly improved efficiency of lead-free inorganic double perovskite solar cell

Development of lead-free inorganic perovskite material, such as Cs2AgBiBr6, is of great importance to solve the toxicity and stability issues of traditional lead halide perovskite solar cells. However, due to a wide bandgap of Cs2AgBiBr6 film, its light absorption ability is largely limited and the photoelectronic conversion efficiency is normally lower than 4.23%. In this text, by using a hydrogenation method, the bandgap of Cs2AgBiBr6 films could be tunable from 2.18 eV to 1.64 eV. At the same time, the highest photoelectric conversion efficiency of hydrogenated Cs2AgBiBr6 perovskite solar cell has been improved up to 6.37% with good environmental stability. Further investigations confirmed that the interstitial doping of atomic hydrogen in Cs2AgBiBr6 lattice could not only adjust its valence and conduction band energy levels, but also optimize the carrier mobility and carrier lifetime. All these works provide an insightful strategy to fabricate high performance lead-free inorganic perovskite solar cells.

Ag implanted TiO2 nanoparticle/nanofibers composites for dye sensitized solar cells applications

With the ultimate goal of commercialization, dye sensitized solar cells (DSSCs) with characteristics like low cost, high stability, fast charge transport and enhanced light harvesting are highly desirable. In order to address all these properties simultaneously; in the present work, Ag ions were doped at fluence of 1013-1016 ions cm−2 with low energy of 120 keV into TiO2 nanoparticle-nanofibers composite based photoanodes in accordance with DFT based simulations. From the XPS measurements it was confirmed that low Ag fluence resulted in substitutional Ag doping whereas interstitial doping starting to overcome in higher fluences. The substitutional Ag implanted TiO2 based photoanodes were found to exhibit higher light absorption and lower number of recombinations of photogenerated charge carriers as compared to photoanode containing interstitial Ag doped TiO2. Finally, DSSCs fabricated with substitutional Ag implanted photoanodes with fluence of 1014 ions cm−2 showed an enhancement of 21.82% against DSSC with unimplanted photoanodes. Herein, a plausible mechanism has been proposed on the basis of DFT and experimental investigations to understand observed enhancement in photovoltaic performance.