Tailored conductive fullerenes-based passivator for efficient and stable inverted perovskite solar cells

Concise Synthesis of Low-Cost Fullerene Derivatives as Electron Transport Materials for Efficient Air-processed Invert Perovskite Solar Cells

Due to its excellent charge extraction ability, fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) is widely used as electron transport materials (ETM) in invert perovskite solar cells. However, the complicated synthetic routes and low productivity of PCBM limiting its commercial application. Moreover, the insufficient defect passivation ability of PCBM is contributed to inferior device performance because it lacks hetero-atoms/groups with lone pair electrons, it is highly desirable for exploration of new fullerene-based ETM with excellent photoelectric properties. Therefore, three new fullerene malonate derivatives were synthesized by simple two-step reaction with a high yield, and then developed as electron transport materials in invert perovskite solar cells which fabricated in air condition. The constituent thiophene and pyridyl group of the fullerene-based ETM can heighten the chemical interaction between under-coordinated Pb²⁺ and lone pair electrons of N, S atom by electrostatic interaction. Hence, the air-processed unencapsulated device with new fullerene-based electron transport materials (C₆₀-bis(pyridin-2-ylmethyl) malonate (C₆₀-PMME)) can obtain a enhanced power conversion efficiency (PCE) of 18.38%, which is significantly higher than the PCBM-based devices (16.64%). Additionally, the C₆₀-PMME-based devices exhibit significantly more outstanding long-term stability than PCBM-based devices, owing to the strong hydrophobic properties of these new fullerene-based ETM. This study shows the promising potentials of these new low-cost fullerene derivatives as ETM to replace commercially used fullerene derivatives PCBM.

Round-comb Fe2O3@SnO2 heterostructures enable efficient light harvesting and charge extraction for high-performance all-inorganic perovskite solar cells

The precise design of an electron transport layer (ETL) to improve the light-harvesting and quality of perovskite (PVK) film plays a crucial role in the photovoltaic performance of n-i-p perovskite solar cells (PSCs). In this work, a novel three-dimensional (3D) round-comb Fe₂O₃@SnO₂ heterostructure composites with high conductivity and electron mobility induced by its Type-II band alignment and matched lattice spacing is prepared and employed as an efficient mesoporous ETL for all-inorganic CsPbBr₃ PSCs. Arising from the multiple light scattering sites provided by the 3D round-comb structure, the diffuse reflectance of Fe₂O₃@SnO₂ composites is increased to improve the light absorption of the deposited PVK film. Besides, the mesoporous Fe₂O₃@SnO₂ ETL affords not only more active surface for sufficient exposure to the CsPbBr₃ precursor solution but also a wettable surface to reduce the barrier for heterogeneous nucleation, which realizes the regulated growth of a high-quality PVK film with less undesired defect. Hence, both the light-harvesting capability, the photoelectrons transport and extraction are improved, and the charge recombination is restrained, delivering an optimized power conversion efficiency (PCE) of 10.23 % with a high short-circuit current density of 7.88 mA cm^-2 for the c-TiO₂/Fe₂O₃@SnO₂ ETL based all-inorganic CsPbBr₃ PSCs. Moreover, under lasting erosion at 25 °C and 85 % RH for 30 days and light-soaking (AM 1.5G) for 480 h in air atmosphere, the unencapsulated-device shows superiorly persistent durability.

From Structural Design to Functional Construction: Amine Molecules in High-Performance Formamidinium-Based Perovskite Solar Cells

Formamidinium (FA) based perovskites are considered as one of the most promising light-absorbing perovskite materials owing to their narrower band gap and better thermal stability compared to conventional methylammonium-based perovskites. Constant improvement by using various additives stimulates the potential application of these perovskites. Amine molecules with different structures have been widely used as typical additives in FA-based perovskite solar cells, and decent performances have been achieved. Thus, a systematic review focusing on structural regulation and functional construction of amines in FA-based perovskites is of significance. Herein, we analyze the construction mechanism of different structural amines on the functional perovskite crystals. The influence of amine molecules on specific perovskite properties including defect conditions, charge transfer, and moisture resistance are evaluated. Finally, we summarize the design rules of amine molecules for the application in high-performance FA-based perovskites and propose directions for the future development of additive molecules.

Recent Developments in Carbon-Based Nanocomposites for Fuel Cell Applications: A Review

Carbon-based nanocomposites have developed as the most promising and emerging materials in nanoscience and technology during the last several years. They are microscopic materials that range in size from 1 to 100 nanometers. They may be distinguished from bulk materials by their size, shape, increased surface-to-volume ratio, and unique physical and chemical characteristics. Carbon nanocomposite matrixes are often created by combining more than two distinct solid phase types. The nanocomposites that were constructed exhibit unique properties, such as significantly enhanced toughness, mechanical strength, and thermal/electrochemical conductivity. As a result of these advantages, nanocomposites have been used in a variety of applications, including catalysts, electrochemical sensors, biosensors, and energy storage devices, among others. This study focuses on the usage of several forms of carbon nanomaterials, such as carbon aerogels, carbon nanofibers, graphene, carbon nanotubes, and fullerenes, in the development of hydrogen fuel cells. These fuel cells have been successfully employed in numerous commercial sectors in recent years, notably in the car industry, due to their cost-effectiveness, eco-friendliness, and long-cyclic durability. Further; we discuss the principles, reaction mechanisms, and cyclic stability of the fuel cells and also new strategies and future challenges related to the development of viable fuel cells.

High-efficiency planar heterojunction perovskite solar cell produced by using 4-morpholine ethane sulfonic acid sodium salt doped SnO2

Perovskite solar cells (PSCs) have become a promising photovoltaic (PV) technology. Meanwhile, developing an electron transport layer (ETL) has been an effective way to promote the power conversion efficiency (PCE) of PSCs. Here, a 4-morpholine ethane sulfonic acid sodium salt (MES Na⁺) doped SnO₂ ETL is utilized in planar heterojunction PSCs. The results show that the MES Na⁺ doped ETL can improve the crystallinity, and absorbance of perovskite films, and passivate interface defects between the perovskite film and SnO₂ ETL. The doping effect accounts for the enhancement of conductivity and the decreasing work function of SnO₂. When 10 mg mL^-1 MES Na⁺ was added to the SnO₂ precursor solution, the device showed the best performance Jsc, Voc, and FF of the PSCs values, which were 23.88 mA cm^-2, 1.12 V and 78.69%, respectively, and the PCE was increased from 17.43% to 21.05%. This doping ETL strategy provides an avenue for defect passivation to further increase the efficiency of perovskite solar cells.