Selection, Preparation and Application of Quantum Dots in Perovskite Solar Cells

As the third generation of new thin-film solar cells, perovskite solar cells (PSCs) have attracted much attention for their excellent photovoltaic performance. Today, PSCs have reported the highest photovoltaic conversion efficiency (PCE) of 25.5%, which is an encouraging value, very close to the highest PCE of the most widely used silicon-based solar cells. However, scholars have found that PSCs have problems of being easily decomposed under ultraviolet (UV) light, poor stability, energy level mismatch and severe hysteresis, which greatly limit their industrialization. As unique materials, quantum dots (QDs) have many excellent properties and have been widely used in PSCs to address the issues mentioned above. In this article, we describe the application of various QDs as additives in different layers of PSCs, as luminescent down-shifting materials, and directly as electron transport layers (ETL), light-absorbing layers and hole transport layers (HTL). The addition of QDs optimizes the energy level arrangement within the device, expands the range of light utilization, passivates defects on the surface of the perovskite film and promotes electron and hole transport, resulting in significant improvements in both PCE and stability. We summarize in detail the role of QDs in PSCs, analyze the perspective and associated issues of QDs in PSCs, and finally offer our insights into the future direction of development

Application of Quantum Dot Interface Modification Layer in Perovskite Solar Cells: Progress and Perspectives

Perovskite solar cells (PSCs) are currently attracting a great deal of attention for their excellent photovoltaic properties, with a maximum photoelectric conversion efficiency (PCE) of 25.5%, comparable to that of silicon-based solar cells. However, PSCs suffer from energy level mismatch, a large number of defects in perovskite films, and easy decomposition under ultraviolet (UV) light, which greatly limit the industrial application of PSCs. Currently, quantum dot (QD) materials are widely used in PSCs due to their properties, such as quantum size effect and multi-exciton effect. In this review, we detail the application of QDs as an interfacial layer to PSCs to optimize the energy level alignment between two adjacent layers, facilitate charge and hole transport, and also effectively assist in the crystallization of perovskite films and passivate defects on the film surface

Recent Advances in Inverted Perovskite Solar Cells: Designing and Fabrication

Inverted perovskite solar cells (PSCs) have been extensively studied by reason of their negligible hysteresis effect, easy fabrication, flexible PSCs and good stability. The certified photoelectric conversion efficiency (PCE) achieved 23.5% owing to the formed lead−sulfur (Pb−S) bonds through the surface sulfidation process of perovskite film, which gradually approaches the performance of traditional upright structure PSCs and indicates their industrial application potential. However, the fabricated devices are severely affected by moisture, high temperature and ultraviolet light due to the application of organic materials. Depending on nitrogen, cost of protection may increase, especially for the industrial production in the future. In addition, the inverted PSCs are found with a series of issues compared with the traditional upright PSCs, such as nonradiative recombination of carriers, inferior stability and costly charge transport materials. Thus, the development of inverted PSCs is systematically reviewed in this paper. The design and fabrication of charge transport materials and perovskite materials, enhancement strategies (e.g., interface modification and doping) and the development of all−inorganic inverted devices are discussed to present the indicator for development of efficient and stable inverted PSCs

A dye-sensitized visible light photocatalyst-Bi24O31Cl10

The p-block semiconductors are regarded as a new family of visible-light photocatalysts because of their dispersive and anisotropic band structures as well as high chemical stability. The bismuth oxide halides belong to this family and have band structures and dispersion relations that can be engineered by modulating the stoichiometry of the halogen elements. Herein, we have developed a new visible-light photocatalyst Bi 24 O 31 Cl 10 by band engineering, which shows high dye-sensitized photocatalytic activity. Density functional theory calculations reveal that the p-block elements determine the nature of the dispersive electronic structures and narrow band gap in Bi 24 O 31 Cl 10. Bi 24 O 31 Cl 10 exhibits excellent visible-light photocatalytic activity towards the degradation of Rhodamine B, which is promoted by dye sensitization due to compatible energy levels and high electronic mobility. In addition, Bi 24 O 31 Cl 10 is also a suitable photoanode material for dye-sensitized solar cells and shows power conversion efficiency of 1.5%

Supported silver nanoparticles as photocatalysts under ultraviolet and visible light irradiation

The significant activity for dye degradation by silver nanoparticles (NPs) on oxide supports was better than popular semiconductor photocatalysts. Moreover, silver photocatalysts can degrade phenol and drive oxidation of benzyl alcohol to benzaldehyde under ultraviolet light. We suggest that surface plasmon resonance (SPR) effect and interband transition of silver NPs can activate organic molecules for oxidation under ultraviolet and visible light irradiation

Mechanism of supported gold nanoparticles as photocatalysts under ultraviolet and visible light irradiation

Gold nanoparticles strongly absorb both visible light and ultraviolet light to drive an oxidation reaction for a synthetic dye, as well as phenol degradation and selective oxidation of benzyl alcohol under UV light

N‑Doped TiO₂ Coupled with Manganese-Substituted Phosphomolybdic Acid Composites As Efficient Photocatalysis-Fenton Catalysts for the Degradation of Rhodamine B

The effectiveness of photocatalytic and Fenton reactions in the synergistic treatment of water pollution problems has become indisputable. In this paper, nitrogen-doped TiO2 was selected as the catalyst for the photocatalytic reaction and manganese-substituted phosphomolybdic acid was used as the Fenton reagent, the two of which were combined together by acid impregnation to construct a binary photocatalysis-Fenton composite catalyst. The degradation experiments of the composite catalyst on RhB indicated that under UV–vis irradiation, the composite catalyst could degrade RhB almost completely within 8 min, and the degradation rate was 19.7 times higher than that of N-TiO2, exhibiting a superior degradation ability. Simultaneously, a series of characterization methods were employed to analyze the structure, morphology, and optical properties of the catalysts. The results demonstrated that the nitrogen doping not only expanded the photo response range of TiO2 but reduced the work function of TiO2, which facilitated the transfer of electrons to the loaded Mn-HPMo side and further promoted the electron–hole separation efficiency. In addition, the introduction of Mn-HPMo provided three pathways for the activation of hydrogen peroxide, which enhanced the degradation activity. This study provides novel insights into the construction of binary and efficient catalysts with multiple hydroxyl radical generation pathways

Facile Fabrication of Hierarchical TiO₂ Nanobelt/ZnO Nanorod Heterogeneous Nanostructure: An Efficient Photoanode for Water Splitting

The TiO₂ nanobelt/ZnO nanorod composite photoelectrodes with flower-like and/or grass-like microstructures have been fabricated via a facile solution growth routine, just by controlling the treatment of the TiO₂ nanobelt substrate. For the flower-like composite, the ZnO nanorods disperse orientationally on TiO₂ nanobelt films, while for the grass-like one, ZnO nanorods grow disorderly like grass on the TiO₂ nanobelt film surface. Furthermore, quasi-Fermi energy level changes of both photoelectrodes have been quantitatively characterized by the surface photovoltage based on the Kelvin probe, which clearly reveals the efficiency of photogenerated electron–hole separation. Owing to the decrease of quasi-Fermi energy level, the flower-like TiO₂ nanobelt/ZnO nanorod heterogeneous nanostructure presents a high efficiency of photogenerated electron–hole separation. Therefore, the flower-like TiO₂ nanobelt/ZnO nanorod heterogeneous nanostructure photoelectrode has achieved a better performance of water splitting compared with the grass-like TiO₂ nanobelt/ZnO nanorod one

High-Performance Photoelectronic Sensor Using Mesostructured ZnO Nanowires

Semiconductor photoelectrodes that simultaneously possess rapid charge transport and high surface area are highly desirable for efficient charge generation and collection in photoelectrochemical devices. Herein, we report mesostructured ZnO nanowires (NWs) that not only demonstrate a surface area as high as 50.7 m²/g, comparable to that of conventional nanoparticles (NPs), but also exhibit a 100 times faster electron transport rate than that in NP films. Moreover, using the comparison between NWs and NPs as an exploratory platform, we show that the synergistic effect between rapid charge transport and high surface area leads to a high performance photoelectronic formaldehyde sensor that exhibits a detection limit of as low as 5 ppb and a response of 1223% (at 10 ppm), which are, respectively, over 100 times lower and 20 times higher than those of conventional NPs-based device. Our work establishes a foundational pathway toward a better photoelectronic system by materials design