Suitable Energy Band Structure Research Articles

Synthesis of CuOQDs/g-C3N4/C Composites Via Stem Template Induction and their Photocatalytic Properties

Introduction: The synthesis of bio-templated porous CuOQDs/g-C3N4/C composites with controllable morphology and suitable energy band structure was successfully carried out via a simple thermal condensation and hydrothermal method. Method: Dicyandiamide and cadmium chloride were selected as starting materials, while Hollyhock stem was chosen as the biological template. The results indicated that, in comparison to pure g-C3N4, g-C3N4/C had a rich porous structure and better-photogenerated carrier separation efficiency. The CuOQDs were anchored evenly on the surface of the g-C3N4, thus resulting in the formation of a greater number of reactive sites. Results: The type-Z heterojunction formed between the CuOQDs and g-C3N4/C reduced the energy required for electron transition, thereby facilitating the separation of photo-generated electronhole pairs. The highest photocatalytic degradation efficiency of CuOQDs/g-C3N4/C for tetracycline (TC) was 65.1%, which was 3.3 times that of pure g-C3N4. Conclusion: In the photocatalytic process, the main reactive species is O2−. The CuOQDs/g- C3N4/C synthesized by stem induction in multi-phase heterojunction form has a stable microstructure to improve the charge separation efficiency. Further, it represents practical photocatalytic environmental protection.

Photocatalytic H2 evolution over CuCoSe2 nanoparticles decorated TiO2 nanosheets with S-scheme charge separation route

The construction of S-scheme heterojunctions via exploring semiconductors with suitable energy band structures can effectively improve the photocatalytic performance of TiO2. In this work, CuCoSe2/TiO2 heterojunction were prepared using solvent evaporation strategy by their different surface charge properties. The investigation indicates that rates of H2 evolution (rH2) of the system increases significantly from 138.1 (TiO2) to 3773.8 μmol·g−1·h−1 (CuCoSe2/TiO2). It is found that the incorporation of CuCoSe2 can extend the visible light absorption range of the system, increase the electrochemically active surface area, facilitate charge generation and decrease the transfer resistance, reduce the H2 production overpotential and the water contact angle. Further investigation reveals that a bimetallic selenide CuCoSe2 exhibit superior enhancement activity compared to their monometallic selenides (CuSe2, CoSe2) due to the synergistic effect of Co and Cu. Especially, the charge transfer between CuCoSe2 and TiO2 follows S-scheme charge separation route, which can effectively enhance charge separation/migration, reserve e− with strong reducing ability in TiO2, thereby promoting the H2 evolution kinetics. Moreover, the heterojunction also demonstrates exceptional stability throughout the cycle experiment. The present work establishes an experimental basis for the advancement of highly efficient and stable bimetallic selenides related heterojunctions in the field of photocatalytic H2 evolution.

Enhanced interfacial electric field via sulfur vacancies modified ZnIn2S4-Vs@NiIn2S4 S-scheme photocatalysts for simultaneous H2 evolution and benzyl alcohol oxidation

Designing and developing efficient photocatalysts for H2 evolution and simultaneous oxidation of benzyl alcohol (BA) in aqueous environments provides a cutting-edge strategy for green synthesis. Nevertheless, the photocatalysts suffer from the low photoconversion efficiency because of the sluggish dynamics and repaid recombination of photogenerated charge carriers, which hindering their widespread applications. To address the limitation, a multifunctionnal sulfur vacancies (SVs) modified ZIS-Vs@NIS S-scheme heterojunction with a strong interfacial electric field effect was synthesized to use photocatalytic H2 production and BA oxidation, simultaneously. Experimental analysis supports that the synergistic effect of SVs and S-scheme heterojunction engineering result in a suitable energy band structure alignment and larger Fermi level potential difference. Those factors can realize effective charge transfer and separation, and enhance the photocatalytic performance. As anticipated, ZIS-Vs@NIS exhibited a superior photocatalytic performance with H2 and benzaldehyde (BAD) yields up to 168.1 and 146.1 μmol under the simulated solar-light irradiation for 1.0 h, respectively, which are approximately 13.3 and 11.8 times higher than pristine ZIS. Moreover, the photocatalytic H2 evolution coupled with BA oxidative dehydrogenation mechanism via S-scheme heterojunction over ZIS-Vs@NIS is also demonstrated in detail.

ZnO/SrTiO3, ZnO/WO3, and ZnO/Zn2SnO4 Bilayer as Electron Transport Layers for Lead Sulfide Colloidal Quantum Dots Solar Cells.

In order to enhance the overall efficiency of colloidal quantum dots solar cells, it is crucial to suppress the recombination of charge carriers and minimize energy loss at the interfaces between the transparent electrode, electron transport layer (ETL), and colloidal quantum dots (CQDs) light-absorbing material. In the current study, ZnO/SrTiO3(STO), ZnO/WO3(TO), and ZnO/Zn2SnO4(ZTO) bilayers are introduced as an ETL using a spin-coating technique. The ZTO interlayer exhibits a smoother surface with a root-mean-square (RMS) value of ≈ 3.28nm compared to STO and TO interlayers, which enables it to cover the surface of the ITO/ZnO substrate entirely and helps to prevent direct contact between the CQDs absorber layer and the ITO/ZnO substrate, thereby effectively preventing efficient charge recombination at the interfaces of the ETL/CQDs. Furthermore, the ZTO interlayer possesses superior electron mobility, a higher visible light transmission, and a suitable energy band structure compared to STO and TO. These characteristics are advantageous for extracting charge carriers and facilitating electron transport. The PbS CQDs solar cell based on the ITO/ZnO/ZTO/PbS-FABr/PbS-EDT/NiO/Au device configuration exhibits the highest efficiency of 15.28%, which is significantly superior than the ITO/ZnO/PbS-FABr/PbS-EDT/NiO/Au solar cell device (PCE = 14.38%). This study is anticipated to offer a practical approach to develop ultrathin and compact ETL for highly efficient CQDSCs.

Enhanced photocatalytic performance of CdZnS nanoparticles and attapulgite/carbon nitride composites by carbon quantum dots mediated facilitated charge separation/transfer: Cr(VI) reduction and H2O2 production

In this work, CdZnS@carbon quantum dots/amino-modified attapulgite/carbon nitride (CdZnS@CQDs/M-ATP/PCN), function as Z-scheme heterojunction photocatalysts, have been successfully prepared by the hydrothermal method. CdZnS@CQDs-1/M-ATP/PCN-1 was optimized toward reduction of Cr(VI) and production of H2O2 under visible light, showing significantly improved photocatalytic performance. After coupling of M-ATP/PCN-1 with CdZnS and a moderate addition of CQDs, the synergistic formation of Z-scheme heterojunctions photocatalytic system effectively enhanced the photocatalytic properties of the composites. The results revealed that the CdZnS@CQDs/M-ATP/PCN catalysts contain rich active centers and suitable energy band structures, which enable them to produce more OH and O2−. Additionally, they also absorb visible light strongly and thus effectively improves the photocatalytic activity. Specifically, the reduction of Cr(VI) by CdZnS@CQDs-1/M-ATP/PCN-1 catalyst was achieved greater than 97.6 %, along with the production of 719.32 μmol·L−1 H2O2. Combining density functional theory (DFT) calculations, experimental test results and characterizations, we find that the excellent photocatalytic performance is attributed to the incorporation of CQDs and the formation of Z-scheme heterojunctions. We have developed a non-precious metal-based efficient Z-scheme photocatalytic system using simple hydrothermal synthesis method, which has a very high potential for energy production, environmentally sustainable remediation, and water purification.

G‐C3N4 Based Composite Materials for Photo‐Fenton Reaction in Water Remediation: A Review of Synthesis Methods, Mechanism and Applications

AbstractOrganic pollutants in water pose significant challenges for water treatment due to their harmful effects and resistance to conventional methods. The rapid increase in industrial wastewater discharge has heightened the need for effective pollutant degradation techniques. Photo‐Fenton technology, an advanced oxidation process, has gained attention for its ability to degrade a wide range of organic contaminants in water. Developing high‐performance photo‐Fenton catalysts is therefore crucial. Graphitic carbon nitride (g‐C3N4) stands out in this field due to its suitable energy band structure, stable properties, and simple synthesis process. However, its application is limited by a low specific surface area, narrow light absorption, and high recombination rate of photogenerated carriers. This review provides a concise overview of current research on g‐C3N4 in photo‐Fenton technology, covering synthesis methods, modifications, and the mechanisms enhancing its photo‐Fenton activity. It also highlights key factors affecting g‐C3N4’s effectiveness in photo‐Fenton reactions and discusses recent advancements in its applications. The review concludes with an analysis of existing challenges and potential future directions for g‐C3N4‐based photo‐Fenton catalysts, offering theoretical insights to advance their industrial use in wastewater treatment.

Defect and doping engineering mediated M-D-MIL(Fe)/Cu-C3N4 heterojunction with dual active centers for efficient tetracycline hydrochloride removal

It is essential to explore Fe-MOFs catalysts containing both multiple active sites and rapid charge separation for improving photo-Fenton performance. Herein, a defect and doping engineering mediated M-D-MIL(Fe)/Cu-C3N4 heterojunction with dual active centers was prepared and its removal performance was investigated against tetracycline hydrochloride. Characterization confirms that: (1) The ligand vacancies in M-D-MIL(Fe) can expose plenty of coordinatively unsaturated metal sites (Fe CUS), which enhance the Lewis acidity and optimize the adsorption of H2O2. Meanwhile, the built-in dual redox centers (Fe3+/Fe2+ and Cu+/Cu2+) can synergistically promote the activation of H2O2. (2) The ligand vacancies in M-D-MIL(Fe) and copper ion in C3N4 as electron trapping sites can optimize the carrier separation of single-component materials. Furthermore, the composites exhibit a suitable energy band structure, an oriented built-in electric field, and tight interfacial contacts, all of which collectively create an optimal pathway and driving force for the efficient transport of photoinduced charges. This, in turn, accelerates the Fe3+/Fe2+ redox cycle. Finally, M-D-MIL(Fe)/Cu-C3N4 demonstrates excellent photo-Fenton performance at low H2O2 concentrations (5 mM), with a kinetic rate (k) of 0.035 min⁻¹, which is 14.58, 18.42, 1.94, and 15.21 times higher than those of MIL-100(Fe), C3N4, M-D-MIL(Fe), and Cu-C3N4, respectively. The study presents an innovative idea with potential applications in environmental restoration.

Achieve efficient photocatalytic degradation of multiple pollutants by constructing WO3-x/BiOBr heterojunctions with hierarchical structure on carbon fibre cloths

Photocatalytic technology has shown excellent application potential in water pollution treatment, but the design and preparation of reusable photocatalysts that can degrade multiple pollutants with high efficiency is a major difficulty limiting the development of this field. Herein, the CF/WO3-x/BiOBr heterojunctions with hierarchical structures were synthesized via a two-step hydrothermal method, in which sheet BiOBr with high-efficiency {001} exposed crystal plane self-assembled into flower-like structure. Due to the unique microstructure control and suitable energy band structure matching, the CF/WO3-x/BiOBr-2.5 M has shown excellent photodegradation effect on a variety of pollutants at the same time (91.2 % for RhB dye, 71.5 % for TCH antibiotic and 88.2 % for Cr(VI) heavy metal pollutant). The synthesis of WO3-x/BiOBr heterojunctions enabled an efficient redox reaction, which facilitated the effective separation and transport of electron-hole pairs. Overall, the results provide a novel approach to designing cloth-based photocatalytic systems with unique structures capable of degrading multiple pollutants.

One-Dimensional Tubular Carbon Nitride Embedded in Ni2P for Enhanced Photocatalytic Activity of H2 Evolution

Graphitic carbon nitride is considered as an ideal semiconductor material for photocatalytic hydrogen evolution due to its suitable energy band structure, durability and environmental friendliness. To further improve the catalytic performance of g-C3N4, nickel phosphide-loaded one-dimensional tubular carbon nitride (Ni2P/TCN) was prepared by thermal polymerization and photo deposition. The beneficial effect of the one-dimensional tubular structure on hydrogen generation was mainly attributed to its larger specific surface area (increased light absorption) as well as the linear movement of the carriers, which reduced their diffusion distance to the surface and facilitated the separation of photogenerated carriers. The loading of Ni2P co-catalyst improved the visible light utilization efficiency and enabled the migration of photogenerated electrons towards Ni2P, which ultimately reacted with the enhanced adsorbed H+ on the Ni2P surface to facilitate the photocatalytic hydrogen evolution process. This study provides new clues for the further development of efficient, environmentally friendly and low-cost g-C3N4 catalysts.

Three-dimension TiO2@NiFe-layered double hydroxide core-shell heterostructures for enhanced photocatalytic phenol hydroxylation

One-step selectively photocatalytic phenol hydroxylation to produce Dihydroxybenzenes (DHB) is an attractive and challenging strategy. However, the rapid recombination of photogenerated carriers existed in single component photocatalyst seriously hinders the photocatalytic efficiency. The heterojunction strategy can optimize the band structure of the photocatalyst, and effectively improve the carriers' separation and transfer during the photocatalytic process. Herein, we successfully designed and prepared a 3D TiO2@Ni3Fe1-LDH core-shell heterostructure photocatalyst by coupling TiO2 nanorods with Ni3Fe1-LDH nanosheets for the photocatalytic phenol hydroxylation to produce DHB. The results showed that the 3D TiO2@Ni3Fe1-LDH core-shell heterostructure had a suitable energy band structure for the photocatalytic phenol hydroxylation and the heterostructure accelerated the carriers’ separation and transfer. Meanwhile, the high porosity and abundant active sites were conducive to the adsorption of H2O2 and the photogenerated carriers transfer efficiency from the photocatalyst to H2O2. The 3D TiO2@Ni3Fe1-LDH core-shell heterostructure showed excellent photocatalytic performance of phenol hydroxylation, where the phenol conversion was 48.6%, and the selectivity of DHB was 81.1% at 25 °C and 4 h of light illumination. Furthermore, the as-prepared photocatalysts exhibited good stability after four cycles of experiment. This work provided a convenient and efficient method for the green synthesis of DHB.

Salt‐melt synthesis of poly(heptazine imide) in binary alkali metal bromides for enhanced visible‐light photocatalytic hydrogen production

AbstractPoly(heptazine imide) (PHI), a semicrystalline version of carbon nitride photocatalyst based on heptazine units, has gained significant attention for solar H2 production benefiting from its advantages including molecular synthetic versatility, excellent physicochemical stability and suitable energy band structure to capture visible photons. Typically, PHI is obtained in salt‐melt synthesis in the presence of alkali metal chlorides. Herein, we examined the role of binary alkali metal bromides (LiBr/NaBr) with diverse compositions and melting points to rationally modulate the polymerization process, structure, and properties of PHI. Solid characterizations revealed that semicrystalline PHI with a condensed π‐conjugated system and rapid charge separation rates were obtained in the presence of LiBr/NaBr. Accordingly, the apparent quantum yield of hydrogen using the optimized PHI reaches up to 62.3% at 420 nm. The density functional theory calculation shows that the dehydrogenation of the ethylene glycol has a lower energy barrier than the dehydrogenation of the other alcohols from the thermodynamic point of view. This study holds great promise for rational modulation of the structure and properties of conjugated polymeric materials.

Improvement of isopropanol sensing performance by surface sensitization of CdSnO3 nanocubes with CdS quantum dots

Perovskite oxides are promising gas-sensing materials due to the stable chemical properties and suitable energy band structure. Quantum dots are low-dimensional nanomaterials with large specific surface areas and rich active sites, which are beneficial to sensing process. Here, the surface of porous CdSnO3 nanocubes were sensitized with CdS quantum dots via a chemical bath deposition strategy and applied to isopropanol sensor. The novel CdS-modified CdSnO3 porous cubes had a large specific surface area. In addition, DFT calculations show that the adsorption of isopropanol by CdS contributes to the recognition of isopropanol among alcohols by CdS/CdSnO3 composite. Combined with the catalytic action of CdS on the oxidation of isopropanol and the formation of n-n heterojunction between CdSnO3 and CdS, the sensor possessed enhanced performance in isopropanol detection. The response of the CdS/CdSnO3 sensor was 20.12 to 100 ppm isopropanol, which was about three times higher than that of pure CdSnO3. And the sensor also possessed superior selectivity to isopropanol, fast response and recovery speed (5/22 s) and low optimum operating temperature (138 °C). This work has reference significance for the construction and understanding of isopropanol-sensing nanomaterials.

Constructing core-shell structured Co3O4–MnWO4 composite photoelectrode with superior PEC water purification performance

Semiconductor photoelectrocatalytic (PEC) technology is one of the most effective methods for removing organic pollutants from wastewater in advanced oxidation processes(AOPs). The selection of suitable semiconductor materials as photoanodes is a crucial factor for achieving superior PEC performance. Here, a core-shell structured Co3O4–MnWO4 architecture is created by enveloping MnWO4 nanoparticles onto the surface of Co3O4 nanowires through a two-step hydrothermal process. The optimized Co3O4–MnWO4-5 photoelectrode showed superior PEC degradation efficiency for KN-R (∼91.2% in 2 h) and durable stability (the accelerated lifetime reached ∼9100 s at a current density of 50 mA cm−2). Three actual wastewaters were also collected to verify the practical applicability of the photoelectrode.The energy consumption was measured at 4.48 kWhm−3, with a COD removal efficiency of 83% and a decolorization rate of 98%. These results demonstrate the excellent performance and promising application of the photoelectrode. The enhancement of PEC performance for the core-shell structured Co3O4–MnWO4 architecture can be attributed to the suitable energy band structure of the Co3O4–MnWO4 composite, higher OEP, larger electrochemical active surface area, accelerated transport of interface carriers, and lower charge transfer resistance. The energy band structure of the Co3O4–MnWO4 composite showed a strong redox ability to induce electrons/holes (e−/h+), which enhances the generation of intermediate active species (hydroxyl radical ·OH and superoxide radicals ·O2-). Therefore, the rationally designed core-shell structured Co3O4–MnWO4 architecture exhibited excellent practical applicability in the degradation of organic pollutants.

Solar-blind ultraviolet photodetector based on Nb2C/β-Ga2O3 heterojunction

β-Ga2O3 has been widely investigated for its stability and thermochemical properties. However, the preparation of β-Ga2O3 thin films requires complex growth techniques and high growth temperatures, and this has hindered the application of β-Ga2O3 thin films. In this study, β-Ga2O3 thin films with good crystalline quality were prepared using a green method, and an ultraviolet (UV) detector based on β-Ga2O3 with a photocurrent of 2.54 × 10–6 A and a dark current of 1.19 × 10–8 A has been developed. Two-dimensional materials have become premium materials for applications in optoelectronic devices due to their high conductivity. Here, we use the suitable energy band structure between Nb2C and Ga2O3 to create a high carrier migration barrier, which reduces the dark current of the device by an order of magnitude. In addition, the device exhibits solar-blind detection, high responsiveness (28 A W−1) and good stability. Thus, the Nb2C/β-Ga2O3 heterojunction is expected to be one of the promising devices in the field of UV photoelectric detection.

Customizing dumbbell-shaped heterostructured artificial photosystems steering versatile photoredox catalysis.

Benefiting from their excellent light-capturing ability, suitable energy band structure and abundant active sites, transition metal chalcogenides (TMCs) have been attracting widespread attention in heterogeneous photocatalysis. Nonetheless, TMCs still suffer from sluggish charge transfer kinetics, a rapid charge recombination rate and poor stability, rendering the construction of high-performance artificial photosystems challenging. Here, a ternary dumbbell-shaped CdS/MoS2/CuS heterostructure with spatially separated catalytically active sites has been elaborately designed. In such a heterostructured nanoarchitecture, MoS2 clusters, selectively grown on both ends of the CdS nanowires (NWs), act as terminal electron collectors, while CuS nanolayers, coated on the sidewalls of CdS NWs through ion exchange, form a P-N heterojunction with the CdS NW framework, which accelerates the migration of holes from CdS to CuS, effectively suppressing the oxidation of sulfide ions and improving the stability of CdS NWs. The well-defined dumbbell-shaped CdS/MoS2/CuS ternary heterostructure provides a structural basis for spatially precise regulation of the charge migration pathway, where photogenerated electrons and holes directionally migrate to the MoS2 and CuS catalytic sites, respectively, ultimately achieving efficient carrier separation and significantly enhancing photoactivity for both photocatalytic hydrogen generation and selective organic transformation under visible light. Moreover, we have also ascertained that such ion exchange and interface configuration engineering strategies are universal. Our work features a simple yet efficient strategy for smartly designing multi-component heterostructures to precisely modulate spatially vectorial charge separation at the nanoscale for solar-to-hydrogen conversion.

Step-scheme CsPbBr3/BiOBr photocatalyst with oxygen vacancies for efficient CO2 photoreduction.

Metal halide perovskites with suitable energy band structures and excellent visible-light responses have emerged as promising photocatalysts for CO2 reduction to valuable chemicals and fuels. However, the efficiency of CO2 photocatalytic reduction often suffers from inefficient separation and sluggish transfer. Herein, a step-scheme (S-scheme) CsPbBr3/BiOBr photocatalyst with oxygen vacancies possessing intimate interfacial contact was fabricated by anchoring CsPbBr3 QDs on BiOBr-Ov nanosheets using a mild anti-precipitation method. The results showed that CsPbBr3/BiOBr-Ov-2 with an internal electric field (IEF) heterojunction exhibited a boosted evolution rate of 27.4 μmol g-1 h-1 (CO: 23.8 μmol g-1 h-1 and CH4: 3.6 μmol g-1 h-1) with an electron consumption rate (Relectron) of 76.4 μmol g-1 h-1, which was 5.9 and 3.2 times that of single CsPbBr3 and BiOBr-Ov, respectively. Density functional theory (DFT) calculations revealed that BiOBr with oxygen vacancies can effectively enhance the adsorption and activation of CO2 molecules. More importantly, in situ infrared Fourier transform spectroscopy (DRIFTS) spectra show the transformation process of the surface species, while the femtosecond transient absorption spectrum (fs-TA) reveals the charge transfer kinetics of the CsPbBr3/BiOBr-Ov. Overall, this work provides some guidance for the rational design of S-scheme heterojunctions and vacancy-engineered photocatalysts, which are expected to have potential applications in the fields of photocatalysis and solar energy conversion.

Construction of Co/Ni-modified P4Mo6 compounds for photocatalytic CO2 conversion

Photocatalytic carbon dioxide reduction reaction (CO2RR) is regarded as a prospective clean and sustainable measure to deal with the environmental problem. In this work, two {P4Mo6}-based compounds were successfully assembled under hydrothermal conditions, formulated as (HL1)8[Co(H7P4Mo6O31)2]·9H2O (1) and [Ni(L2)3]4·[Ni(H7P4Mo6O31)2]·12H2O (2) [L1 = 4-phenylpyridine; L2 = 2-(2-pyridyl)benzimidazole]. Single crystal X-ray diffraction (SCXRD) analysis shows that compounds 1 and 2 are both assembled on the basis of one [M(P4Mo6)2] (M = Co or Ni) unit with the hourglass-shaped structure. More interestingly, the suitable energy band structures of M (M = Co or Ni) species in {P4Mo6} clusters make the potential CO2 photoreduction of compound 1 is better than compound 2. Beside, the results show that CO yields are 1178.11 μmol g−1 h−1 (1) and 878.32 μmol g−1 h−1 (2) for 8 h irradiation.

InGaN nanorods/CuBi2O4 heterojunction photoanodes for photoelectrochemical water splitting

Semiconductor heterojunctions designed by a rational energy band structure can be well accelerated for charge separation, which leads to improved photoelectrochemical (PEC) performance. Using an economical HCVD process, one-dimensional InGaN nanorods were produced in this work. CuBi2O4 was successfully loaded onto the surface of InGaN nanorods using electrodeposition and annealing techniques to produce p-n heterojunction n-InGaN/p-CuBi2O4 photoanodes for the first time. Attributed to the suitable energy band structure, the resulting heterojunction photoanodes exhibit effective charge separation and transfer through the potential gradient. The optimized photoanode achieves a photocurrent density of 5.6 mA/cm2 at 1.23 V vs. RHE, which is 10.2 times greater than that of pure InGaN nanorods. In addition, the InGaN/CuBi2O4 heterojunction exhibits improved stability over previous work. This work paves the path for the rational design and construction of heterojunction photoanodes based on InGaN.

Performance optimization of all-inorganic CsGeI3 solar cells: SCAPS simulation and DFT calculation

It is well known that conventional organic–inorganic perovskite solar cells (PSCs) have unstable performance, while inorganic perovskite solar cells are stable but have low conversion efficiency. In order to achieve the goal of improving the conversion efficiency of solar cells, we design an inorganic germanium-base perovskite solar cells (FTO/Cd0.5Zn0.5S/IDL1/CsGeI3/IDL2/CuI/Au) to enhance the performance of the cells. We have investigated and optimized the overall performance of the solar cell using SCAPS-1D software simulation and combined with DFT calculations. Through the study, we found that CsGeI3 exhibits excellent electronic properties and ionization characteristics, which makes it suitable as an efficient absorber layer. And Cd0.5Zn0.5S and CuI have suitable energy band structures to match CsGeI3. A unique phosphorus bridge is formed on the surface of Cd0.5Zn0.5S, which realizes effective charge separation, and the valence band offset of CuI is low, so this structure is designed by us to further enhance the conversion efficiency of solar cells. We derived the photovoltaic properties of CsGeI3 through DFT calculations and found that there is a strong interaction between Ge2+ and I-, which also provides a theoretical basis for us to use CsGeI3 as an absorber layer. We have further tuned the interfacial defect layer (electron affinity, thickness), Electron transport layer (ETL) and Hole transport layer (HTL) (bandgap, defect density, thickness), absorber layer (bandgap, subjected to the main doping concentration), and operating temperature of the solar cell. It is shown that IDL1 and IDL2 have asymmetry and that IDL1 plays a major role in influencing the performance of solar cells. And too high defect density will make more defects and composite centers inside the ETL, which will reduce the quality of the ETL interface. After the final optimization, we increased the Fill Factor (FF) of the solar cell to 85.77 % and Power Conversion Efficiency (PCE) to 25.83 %. Our study provides theoretical support for the development of novel all-inorganic CsGeI3 perovskite solar cells.

Hybrid Mesoporous TiO2/ZnO Electron Transport Layer for Efficient Perovskite Solar Cell.

In recent years, perovskite solar cells (PSCs) have gained major attention as potentially useful photovoltaic technology due to their ever-increasing power-conversion efficiency (PCE). The efficiency of PSCs depends strongly on the type of materials selected as the electron transport layer (ETL). TiO2 is the most widely used electron transport material for the n-i-p structure of PSCs. Nevertheless, ZnO is a promising candidate owing to its high transparency, suitable energy band structure, and high electron mobility. In this investigation, hybrid mesoporous TiO2/ZnO ETL was fabricated for a perovskite solar cell composed of FTO-coated glass/compact TiO2/mesoporous ETL/FAPbI3/2D perovskite/Spiro-OMeTAD/Au. The influence of ZnO nanostructures with different percentage weight contents on the photovoltaic performance was investigated. It was found that the addition of ZnO had no significant effect on the surface topography, structure, and optical properties of the hybrid mesoporous electron-transport layer but strongly affected the electrical properties of PSCs. The best efficiency rate of 18.24% has been obtained for PSCs with 2 wt.% ZnO.