Effect of an Al-doped ZnO electron transport layer on the efficiency of inverted bulk heterojunction solar cells

Doping is a widely-implemented strategy for enhancing the inherent electrical properties of metal oxide charge transport layers in photovoltaic devices because higher conductivity of electron transport layer (ETL) can increment the photocurrent by reducing the series resistance. To improve the conductivity of ETL, in this study we doped the ZnO layer with aluminum (Al), then investigated the influence of AZO on the performance of inverted bulk heterojunction (BHJ) polymer solar cells based on poly [[4,8-bis [(2-ethylhexyl)oxy]benzo [1,2-b:4,5-b’]dithiophene-2,6-diyl]-[3-fluoro-2[(2-ethylhexyl)-carbonyl]-thieno-[3,4-b]thiophenediyl ]] (PTB7):[6,6]-phenyl C71 butyric acid methyl ester (PC₇₁BM). The measured conductivity of AZO was ~10⁻³ S/cm, which was two orders of magnitude higher than that of intrinsic ZnO (~10⁻⁵ S/cm). By decreasing the series resistance (R_s) in a device with an AZO layer, the short circuit current (J_sc) increased significantly from 15.663 mA/cm² to 17.040 mA/cm². As a result, the device with AZO exhibited an enhanced power conversion efficiency (PCE) of 8.984%.     

MgO和Fe2O3的添加对GDCSi体系微观结构及电化学性能的影响

采用溶胶凝胶法制备Gd_0.2Ce_0.8O_3-δ +0.05%（质量分数）SiO₂（GDCSi）电解质。在GDCSi体系中加入Fe₂O₃及MgO可达到降低烧结温度的同时提高晶界电导率，并减小杂质SiO₂对氧离子在晶界处传输的阻碍的目的。将MgO和Fe₂O₃单掺杂或双掺杂在GDCSi体系中并对GDCSi基电解质的微观形貌及电性能进行研究。结果表明，所有样品主要由立方萤石结构相组成；物质的量分数4%MgO单掺杂的GDCSi-M、物质的量分数4%Fe₂O₃单掺杂的GDCSi-F以及物质的量分数2%MgO-物质的量分数2%Fe₂O₃共掺杂的GDCSi-MF均可促进GDCSi体系晶粒增长，降低晶粒间孔隙率，提高电解质的相对密度，降低晶粒电阻R_gi、晶界电阻R_gb及总电阻R_t；GDCSi-MF具有最高晶界电导率和总电导率，在400 ℃时GDCSi-MF的晶界电导率σ_gb和总电导率σ_t分别是GDCSi的10.41和1.82倍。     

Engineering nanostructures of CuO-based photocatalysts for water treatment: Current progress and future challenges

Nowadays, increasing extortions regarding environmental problems and energy scarcity have stuck the development and endurance of human society. The issue of inorganic and organic pollutants that exist in water from agricultural, domestic, and industrial activities has directed the development of advanced technologies to address the challenges of water scarcity efficiently. To solve this major issue, various scientists and researchers are looking for novel and effective technologies that can efficiently remove pollutants from wastewater. Nanoscale metal oxide materials have been proposed due to their distinctive size, physical and chemical properties along with promising applications. Cupric Oxide (CuO) is one of the most commonly used benchmark photocatalysts in photodegradation owing to the fact that they are cost-effective, non-toxic, and more efficient in absorption across a significant fraction of solar spectrum. In this review, we have summarized synthetic strategies of CuO fabrication, modification methods with applications for water treatment purposes. Moreover, an elaborative discussion on feasible strategies includes; binary and ternary heterojunction formation, Z-scheme based photocatalytic system, incorporation of rare earth/transition metal ions as dopants, and carbonaceous materials serving as a support system. The mechanistic insight inferring photo-induced charge separation and transfer, the functional reactive radical species involved in a photocatalytic reaction, have been successfully featured and examined. Finally, a conclusive remark regarding current studies and unresolved challenges related to CuO are put forth for future perspectives.     

碳自掺杂g-C3N4光催化性能的原位光微量热-荧光光谱研究

通过在尿素前驱体中添加单宁酸, 原位缩聚形成碳自掺杂石墨相氮化碳(g-C₃N₄). 利用X射线光电子能谱(XPS)、 场发射扫描电子显微镜(FESEM)、 X射线衍射(XRD)仪和同步热分析(TG-DSC)等方法对碳自掺杂 g-C₃N₄的形貌、 物相结构和能带价态组分进行表征分析, 结合紫外-可见吸收光谱(UV-Vis)和原位光微量热-荧光光谱联用仪获得碳自掺杂g-C₃N₄降解罗丹明B的原位热/动力学信息和三维荧光光谱信息, 探讨了光催化降解罗丹明B的微观机制. 结果表明, 单宁酸浓度≤10 mg/mL时, 碳会取代七嗪单元结构的氮原子形成g-C₃N₄骨架碳自掺杂; 单宁酸浓度≥ 20 mg/mL时, 碳以无定形形式沉积负载在g-C₃N₄表面上形成无定形碳自掺杂. 骨架碳自掺杂g-C₃N₄形成的π电子有效缩短了禁带宽度, 减小了光生电子-空穴复合几率, 比无定形C掺杂g-C₃N₄显示出更优异的光催化性能, 催化主要活性物种为h⁺和·O{}_{\mathrm{2}}^{-}. 碳自掺杂g-C₃N₄光催化降解过程可分为光响应吸热、 降解污染物放热平衡过程和稳定放热3个过程. 其中骨架碳自掺杂g-C₃N₄(C/N摩尔比为0.844)在光照1000 s内, 三维荧光光谱检测的RhB降解率锐减, 光照1000 s后, 其RhB降解率为87.6%, 分别是原始g-C₃N₄和无定形碳自掺杂g-C₃N₄的3.13倍和1.95倍. 光照1000 s后, 光微量热计显示以矿化和降解非荧光发色中间产物为主, 并保持以热变速率为(0.9799±0.5356) μJ/s稳定放热, 为拟零级反应过程, 是光催化反应的决速步骤.     

高比能锂离子电池层状富锂正极材料改性策略研究进展

层状富锂材料具有超过250 mAh∙g⁻¹的高可逆比容量,被认为是下一代高比能锂离子电池最具商业化前景的正极材料之一。然而,层状富锂材料在实际应用之前仍需解决诸多挑战,如高电压氧释放、层状到岩盐相的结构变化、过渡金属离子迁移等结构劣化,并由此带来了较低的初始库伦效率、电压/容量的衰减以及循环寿命的不足。针对以上问题,进行层状富锂材料改性无疑是一种行之有效的方法。本综述全面介绍了层状富锂材料的结构、组分以及电化学性能,在此基础上对材料改性策略进行了系统阐述,详细介绍了体相掺杂、表面包覆、缺陷设计、离子交换和微结构调控等一系列改性策略的现状以及发展趋势,最终提出了高容量和长循环层状富锂材料和高比能锂离子电池的设计思路。     

Aggregation-Induced Emission by Molecular Design: A Route to High-Performance Light-Emitting Electrochemical Cells

The emission efficiency of organic semiconductors (OSCs) often suffers from aggregation caused quenching (ACQ). An elegant solution is aggregation-induced emission (AIE), which constitutes the design of the OSC so that its morphology inhibits quenching π–π interactions and non-radiative motional deactivation. The light-emitting electrochemical cell (LEC) can be sustainably fabricated, but its function depends on motion of bulky ions in proximity of the OSC. It is therefore questionable whether the AIE morphology can be retained during LEC operation. Here, we synthesize two structurally similar OSCs, which are distinguished by that 1 features ACQ while 2 delivers AIE. Interestingly, we find that the AIE-LEC significantly outperforms the ACQ-LEC. We rationalize our finding by showing that the AIE morphology remains intact during LEC operation, and that it can feature appropriately sized free-volume voids for facile ion transport and suppressed non-radiative excitonic deactivation.     

Sterically-Hindered Molecular p-Dopants Promote Integer Charge Transfer in Organic Semiconductors

Molecular p-dopants designed to undergo electron transfer with organic semiconductors are typically planar molecules with high electron affinity. However, their planarity can promote the formation of ground-state charge transfer complexes with the semiconductor host and results in fractional instead of integer charge transfer, which is highly detrimental to doping efficiency. Here, we show this process can be readily overcome by targeted dopant design exploiting steric hindrance. To this end, we synthesize and characterize the remarkably stable p-dopant 2,2′,2′′-(cyclopropane-1,2,3-triylidene)tris(2-(perfluorophenyl)acetonitrile) comprising pendant functional groups that sterically shield its central core while retaining high electron affinity. Finally, we demonstrate it outperforms a planar dopant of identical electron affinity and increases the thin film conductivity by up to an order of magnitude. We believe exploiting steric hindrance represents a promising design strategy towards molecular dopants of enhanced doping efficiency.     

Superatom-in-Superatom Nanoclusters: Synthesis,Structure, and Photoluminescence

We report a new strategy in which a thiolate-protected Ag₂₅ nanocluster can be doped with open d-shell group 8 (Ru, Os) and 9 (Ir) metals by forming metal hydride (RuH₂, OsH₂, IrH) superatoms with a closed d-shell. Structural analyses using various experimental and theoretical methods revealed that the Ag₂₅ nanoclusters were co-doped with the open d-shell metal and hydride species to produce superatom-in-superatom nanoclusters, establishing a novel superatom doping phenomenon for open d-shell metals. The synthesized superatom-in-superatom nanoclusters exhibited dopant-dependent photoluminescence (PL) properties. Comparative PL lifetime studies of the Ag₂₅ nanoclusters doped with 8–10 group metals revealed that both radiative and nonradiative processes were significantly dependent on the dopant. The former is strongly correlated with the electron affinity of the metal dopant, whereas the latter is governed predominantly by the kernel structure changed upon the doping of the metal hydride(s).     

Hexaazatriphenylene-Based Two-Dimensional Conductive Covalent Organic Framework with Anisotropic Charge Transfer

The development of covalent organic frameworks (COFs) with efficient charge transport is of immense interest for applications in optoelectronic devices. To enhance COF charge transport properties, electroactive building blocks and dopants can be used to induce extended conduction channels. However, understanding their intricate interplay remains challenging. We designed and synthesized a tailor-made COF structure with electroactive hexaazatriphenylene (HAT) core units and planar dioxin (D) linkages, denoted as HD-COF. With the support of theoretical calculations, we found that the HAT units in the HD-COF induce strong, eclipsed π–π stacking. The unique stacking of HAT units and the weak in-plane conjugation of dioxin linkages leads to efficient anisotropic charge transport. We fabricated HD-COF films to minimize the grain boundary effect of bulk COFs, which resulted in enhanced conductivity. As a result, the HD-COF films showed an electrical conductivity as high as 1.25 S cm⁻¹ after doping with tris(4-bromophenyl)ammoniumyl hexachloroantimonate.     

发光可调Au:ZnCdS合金量子点的水相合成

以巯基丙酸作为配体,在水溶液中合成了发光位置在495~583 nm可调的Au∶Zn Cd S合金量子点,研究了掺杂含量、Zn/Cd比和p H等对量子点光学性质的影响。对预提纯的Au∶Zn Cd S核量子点进行Zn S包覆,量子点表面的缺陷被有效去除,发光效率明显提高。利用X-射线粉末衍射、透射电子显微镜对其结构和形貌进行了表征。