Improved Performance of Printable Perovskite Solar Cells with Bifunctional Conjugated Organic Molecule

A bifunctional conjugated organic molecule 4‐(aminomethyl) benzoic acid hydroiodide (AB) is designed and employed as an organic cation in organic–inorganic halide perovskite materials. Compared with the monofunctional cation benzylamine hydroiodide (BA) and the nonconjugated bifunctional organic molecule 5‐ammonium valeric acid, devices based on AB‐MAPbI₃ show a good stability and a superior power conversion efficiency of 15.6% with a short‐circuit current of 23.4 mA cm^?2, an open‐circuit voltage of 0.94 V, and a fill factor of 0.71. The bifunctional conjugated cation not only benefits the growth of perovskite crystals in the mesoporous network, but also facilitates the charge transport. This investigation helps explore new approaches to rational design of novel organic cations for perovskite materials.     

Cross‐Linkable and Dual Functional Hybrid Polymeric Electron Transporting Layer for High‐Performance Inverted Polymer Solar Cells

A cross‐linkable dual functional polymer hybrid electron transport layer (ETL) is developed by simply adding an amino‐functionalized polymer dopant (PN4N) and a light crosslinker into a commercialized n‐type semiconductor (N2200) matrix. It is found that the resulting hybrid ETL not only has a good solvent resistance, facilitating multilayers device fabrication but also exhibits much improved electron transporting/extraction properties due to the doping between PN4N and N2200. As a result, by using PTB7‐Th:PC₇₁BM blend as an active layer, the inverted device based on the hybrid ETL can yield a prominent power conversion efficiency of around 10.07%. More interestingly, photovoltaic property studies of bilayer devices suggest that the absorption of the hybrid ETL contributes to photocurrent and hence the hybrid ETL simultaneously acts as both cathode interlayer material and an electron acceptor. The resulting inverted polymer solar cells function like a novel device architectures with a combination of a bulk heterojunction device and miniature bilayer devices. This work provides new insights on function of ETLs and may be open up a new direction for the design of new ETL materials and novel device architectures to further improve device performance.     

MoOx thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

Abstract

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoO_x films (2  x  2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li₂SO₄. The MoO_x (x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm^?2 measured at 5 mV s^?1), best rate capability and excellent stability at potentials below ?0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO₂ nanocrystals and amorphous MoO_x (2.3 < x  3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO₂ grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.     

Tailoring and Modifying an Organic Electron Acceptor toward the Cathode Interlayer for Highly Efficient Organic Solar Cells

With the rapid advance of organic photovoltaic materials, the energy level structure, active layer morphology, and fabrication procedure of organic solar cells (OSCs) are changed significantly. Thus, the photoelectronic properties of many traditional electrode interlayers have become unsuitable for modifying new active layers; this limits the further enhancement in OSC efficiencies. Herein, a new design strategy of tailoring the end-capping unit, ITIC, to develop a cathode interlayer (CIL) material for achieving high power conversion efficiency (PCE) in OSCs is demonstrated. The excellent electron accepting capacity, suitable energy level, and good film-forming ability endow the S-3 molecule with an outstanding electron extraction property. A device with S-3 shows a PCE of 16.6%, which is among the top values in the field of OSCs. More importantly, it is demonstrated that the electrostatic potential difference between the CIL molecule and the polymer donor plays a crucial role in promoting exciton dissociation at the CIL/active layer interface, contributing to additional charge generation; this is crucial for enhancement of the current density. The results of this work not only develop a new design strategy for high-performance CIL, but also demonstrate a reliable approach of density functional theory (DFT) calculation to predict the effect of the CIL chemical structure on exciton dissociation in OSCs.     

Printable CsPbI3 Perovskite Solar Cells with PCE of 19% via an Additive Strategy

All-inorganic CsPbI₃ holds promise for efficient tandem solar cells, but reported fabrication techniques are not transferrable to scalable manufacturing methods. Herein, printable CsPbI₃ solar cells are reported, in which the charge transporting layers and photoactive layer are deposited by fast blade-coating at a low temperature (≤100 °C) in ambient conditions. High-quality CsPbI₃ films are grown via introducing a low concentration of the multifunctional molecular additive Zn(C₆F₅)₂, which reconciles the conflict between air-flow-assisted fast drying and low-quality film including energy misalignment and trap formation. Material analysis reveals a preferential accumulation of the additive close to the perovskite/SnO₂ interface and strong chemisorption on the perovskite surface, which leads to the formation of energy gradients and suppressed trap formation within the perovskite film, as well as a 150 meV improvement of the energetic alignment at the perovskite/SnO₂ interface. The combined benefits translate into significant enhancement of the power conversion efficiency to 19% for printable solar cells. The devices without encapsulation degrade only by ≈2% after 700 h in air conditions.     

Stratified Oxygen Vacancies Enhance the Performance of Mesoporous TiO2 Electron Transport Layer in Printable Perovskite Solar Cells

The low electrical conductivity and the high surface defect density of the TiO₂ electron transport layer (ETL) limit the power conversion efficiency (PCE) of corresponding perovskite solar cells (PSCs). Here, the conductivity and defect modulation of the mesoporous TiO₂ (mp-TiO₂) ETL via oxygen vacancy (OV) management by the reduction and oxidation treatment are reported. Reduction treatment via reducing agent introduces abundant OVs into the TiO₂ nanocrystalline particles on the surface and at the subsurface. The following oxidation treatment via hydrogen peroxide removes the surface OVs while remains the subsurface OVs, resulting in stratified OVs. The stratified OVs improve the conductivity of TiO₂ ETL by increasing carrier donors and decrease nonradiative centers by reducing surface defects. Such synergy ensures the capability of mp-TiO₂ as the well-performed ETL with improved energy level alignment, suppressed interface recombination, enhanced carrier extraction, and transport. As a result, printable hole-conductor-free carbon-based mesoscopic PSCs based on the modulated mp-TiO₂ ETL demonstrate a highest reported PCE of 18.96%.     

Recent Progress in Organic Electron Transport Materials in Inverted Perovskite Solar Cells

Organic n‐type materials (e.g., fullerene derivatives, naphthalene diimides (NDIs), perylene diimides (PDIs), azaacene‐based molecules, and n‐type conjugated polymers) are demonstrated as promising electron transport layers (ETLs) in inverted perovskite solar cells (p–i–n PSCs), because these materials have several advantages such as easy synthesis and purification, tunable frontier molecular orbitals, decent electron mobility, low cost, good solubility in different organic solvents, and reasonable chemical/thermal stability. Considering these positive factors, approaches toward achieving effective p–i–n PSCs with these organic materials as ETLs are highlighted in this Review. Moreover, organic structures, electron transport properties, working function of electrodes caused by ETLs, and key relevant parameters (PCE and stability) of p–i–n PSCs are presented. Hopefully, this Review will provide fundamental guidance for future development of new organic n‐type materials as ETLs for more efficient p–i–n PSCs.     

固体氧化物燃料电池阳极材料成份的优化规律

本研究借助第一性原理总能量计算法, 针对可能用于固体氧化物燃料电池阳极材料的3~6周期金属元素及其氧化物, 进行了稳定性、电学性能及力学性能等方面的研究。对工作条件下(高温、还原性气氛)阳极的结构形态、综合性能等的演化情况进行了研究分析, 得到了金属/氧化物体系体模量、禁带宽度的变化趋势, 及其与稳定性的关系。结果显示, 位于生成趋势图中部区域的金属/氧化物稳定性适中, 易于发生氧化/还原反应, 可能是阳极工作条件下综合性能较优的原因, 其中靠近金属区的元素更能为体系提供电子电导和催化活性, 靠近氧化物区的元素更能为体系提供氧离子并增加稳定性, 这些结果为不同条件下的阳极选择提供了理论指导。     

微管式固体氧化物燃料电池阳极微结构及其性能

利用相转化纺丝法制备了NiO-YSZ中空纤维, 在其外表面负载YSZ膜1450℃共烧后形成YSZ/NiO-YSZ双层中空纤维。阳极孔结构通过芯液(N-甲基砒咯烷酮(NMP)+乙醇)中溶剂NMP的含量来控制。 当NMP含量从0、30wt%、50wt%、70wt%增加到100wt%时, 阳极的孔结构由指状孔/海绵孔/指状孔三明治结构逐渐成为贯通的指状孔结构, 电解质膜致密性、还原后的双层中空纤维的机械强度、阳极电导率逐渐减小, 而孔隙率则增加。多孔的阴极Ag涂敷于致密的电解质膜外表面构成微管SOFC。H₂/空气微管SOFC的浓差极化随着指状孔长度的增加而减小, 当NMP含量为70wt%时, 输出性能最佳, 最大功率密度为662 mW/cm² (800℃), 此时极化阻抗最小。     

固体氧化物直接碳燃料电池新型阳极研究进展

固体氧化物直接碳燃料电池采用固体氧化物作为电解质, 能够将碳燃料的化学能直接转化为电能, 具有效率高、燃料适应性广、利于CO₂捕集等优点, 在能源与环境问题日益突出的现实条件下展现出广阔的应用前景。固体氧化物直接碳燃料电池中的关键问题在于研发合适的碳燃料转化阳极, 以满足反应催化、物质输运以及杂质耐受等要求。本文系统地总结并分析了多孔固体阳极、熔融碳酸盐阳极和液态金属阳极三类直接燃料电池阳极的结构特性、工作原理、材料特性等, 特别关注了以液态金属作为阳极的直接碳燃料电池, 分析了该类电极的优势, 探讨了未来固体氧化物直接碳燃料电池阳极的发展方向。     

A Cost-Effective,Aqueous-Solution-Processed Cathode Interlayer Based on Organosilica Nanodots for Highly Efficient and Stable Organic Solar Cells

The performance and industrial viability of organic photovoltaics are strongly influenced by the functionality and stability of interface layers. Many of the interface materials most commonly used in the lab are limited in their operational stability or their materials cost and are frequently not transferred toward large-scale production and industrial applications. In this work, an advanced aqueous-solution-processed cathode interface layer is demonstrated based on cost-effective organosilica nanodots (OSiNDs) synthesized via a simple one-step hydrothermal reaction. Compared to the interface layers optimized for inverted organic solar cells (i-OSCs), the OSiNDs cathode interlayer shows improved charge carrier extraction and excellent operational stability for various model photoactive systems, achieving a remarkably high power conversion efficiency up to 17.15%. More importantly, the OSiNDs’ interlayer is extremely stable under thermal stress or photoillumination (UV and AM 1.5G) and undergoes no photochemical reaction with the photoactive materials used. As a result, the operational stability of inverted OSCs under continuous 1 sun illumination (AM 1.5G, 100 mW cm⁻²) is significantly improved by replacing the commonly used ZnO interlayer with OSiND-based interfaces.