Designing Hole Transport Materials with High Hole Mobility and Outstanding Interface Properties for Perovskite Solar Cells

Organic–inorganic halide perovskite solar cells (PSCs) have attracted much attention due to their rapid increase in power conversion efficiencies (PCEs), and many efforts are devoted to further improving the PCEs. Designing highly efficient hole transport materials (HTMs) for PSCs may be one of the effective ways. Herein we theoretically designed three new HTMs (FDT−N, FDT−O, and FDT−S) by introducing a nitrogen-phenyl group, an oxygen atom, and a sulfur atom into the spiro core of an experimentally synthesized HTM (FDT), respectively. And then we performed quantum chemical calculation to study their application potential. The results show that the devices with FDT−O and FDT−S instead of FDT may have higher open circuit voltages owing to their lower highest occupied molecular orbital (HOMO) energy levels. Moreover, FDT−S exhibits the best hole transport performance among the studied HTMs, which may be due to the significant HOMO-HOMO overlap in the hole hopping path with the largest transfer integral. Furthermore, the results on interface properties indicate that introducing oxygen and sulfur atoms can enhance the MAPbI₃/HTM interface interaction. The present work not only offers two promising HTMs (FDT−O and FDT−S) for PSCs but also provides theoretical help for subsequent research on HTMs.     

螺芳基钙钛矿太阳能电池空穴传输材料研究进展

近10年, 第三代光电能源转换技术钙钛矿太阳能电池(PSCs)正迅速崛起. 基于有机-无机杂化钙钛矿材料的本征半导体特性以及PSCs平面多层器件架构特点, 采用有机小分子空穴传输材料(HTMs)作为PSCs的p-型层, 不仅实现了PSCs器件的全固态化, 且大幅提升了器件效率及稳定性. 以当前通用的标准空穴传输材料spiro-OMeTAD (2,2′,7,7′-四[N,N-二(4-甲氧基苯基)氨基]-9,9′-螺二芴)为模板, 研究人员开展了众多结构剖析和改进工作. 分子spiro-OMeTAD中, 三维螺二芴(SBF)核能以较小的空间集成更多的空穴传输单元; 而芳胺优异的p-型特性, 使其成为高效的电活性单元. 经典螺芳核SBF制备成本高, 可修饰位置单一; 因此, 基于spiro-OMeTAD的结构改进主要围绕芳胺单元的修饰开展. 随着HTMs分子设计以及合成方法学的进展, 近5年来, 一系列低成本、高性能的类SBF螺芳基单元逐渐兴起, 并迅速进入空穴传输材料领域, 如: 螺[芴-9,9′-氧杂蒽]、螺吖啶、螺硫杂蒽等. 螺芳基核结构的日益丰富, 大大拓展了HTMs分子的设计空间, 从而推动了PSCs效率和稳定性的不断提升. 因此, 本综述聚焦含螺芳烃骨架的HTMs分子, 根据其器件性能表现, 分析高性能材料的结构要素. 按照螺芳烃核结构对高性能HTMs进行分类归纳, 总结了结构设计思路和构效关系. 期望通过较为全面的评述, 为HTMs分子构建提供可参考的策略, 从而推动PSCs继续向高效率、长寿命的实用化方向发展.     

一种非线性结构空穴传输材料的合成及其光伏性能研究

以三苯胺为电子给体单元,4-叔丁基-甲氧基苯环为母核,设计合成了1种非线性“Y型”结构的空穴传输材料（2TPA-ph-tbyl）。光电化学测试结果表明该材料与钙钛矿材料能级匹配。单晶X射线衍射结果表明,该分子通过端位基团三苯胺形成分子间C-H/π相互作用。这种较强的侧链堆积作用使2TPA-ph-tbyl获得了3.13× 10-5 cm2 V-1 s-1的空穴迁移率,是商用空穴传输材料PEDOT：PSS的1.5倍。将其制备成倒置结构钙钛矿太阳能电池,开路电压达到1000 mV、短路电流密度为21.53 mA?cm-2,填充因子为0.71,其光电转换效率达到15.2%,高于PEDOT：PSS（13.7%）。稳态光致发光和阻抗测试表明,2TPA-ph-tbyl可以促进钙钛矿-空穴传输材料界面电荷传输,降低界面电荷复合,从而提高电池的开路电压和短路电流。上述结果表明,具有非线性结构的空穴传输材料可以通过增强分子间的侧链堆积效应,提高材料的空穴迁移率,进而提高电池的光电转换效率。     

钙钛矿太阳能电池电子传输层的制备及应用

目前,有机-无机杂化钙钛矿太阳能电池(PSC)的器件效率已经超过25％.电子传输层作为PSC中的重要组成部分在提取和传输光生电子,阻挡空穴,修饰界面,调节界面能级和减少电荷复合等方面起着关键作用.无机n型材料,例如TiO2、ZnO、SnO2和其他金属氧化物材料具有成本低和稳定性好的特点,经常在传统PSC中被用作电子传输...     

Dendritic-Like Molecules Built on a Pillar[5]arene Core as Hole Transporting Materials for Perovskite Solar Cells

Multi-branched molecules have recently demonstrated interesting behaviour as charge-transporting materials within the fields of perovskite solar cells (PSCs). For this reason, extended triarylamine dendrons have been grafted onto a pillar[5]arene core to generate dendrimer-like compounds, which have been used as hole-transporting materials (HTMs) for PSCs. The performances of the solar cells containing these novel compounds have been extensively investigated. Interestingly, a positive dendritic effect has been evidenced as the hole transporting properties are improved when going from the first to the second-generation compound. The stability of the devices based on the best performing pillar[5]arene material has been also evaluated in a high-throughput ageing setup for 500 h at high temperature. When compared to reference devices prepared from spiro-OMeTAD, the behaviour is similar. An analysis of the economic advantages arising from the use of the pillar[5]arene-based material revealed however that our pillar[5]arene-based material is cheaper than the reference.     

两亲8-氨基喹啉衍生物的空穴传输特性及LB膜电致发光器件

在过去的20年里,电致发光(EL)领域的研究显得异常活跃,EL已应用于通讯、信息、显示等许多领域,而占领这一领域的是P-N结无机半导体发光二级管,其发光效率已超过了白炽灯.但由于无机半导体很难实现大面积平面显示,加之成本较高,因此,限制了其进一步的发展[1].有机荧光材料的种类繁多,荧光量子效率高,且可以通过分子结构修饰有目的地控制其发光效率、发光颜色和电学性能[2],因而,越来越多的学术界和工业界的研究小组进入了有机电致发光研究领域[3.4].     

Economical and Environmentally Friendly Organic hydrazone Derivatives Characterized by a Heteroaromatic Core as Potential Hole Transporting Materials in Perovskite Solar Cells

A series of organic electron-rich π-bridged symmetric hydrazones, composed of two donor moieties connected through a thiophene- or a pyrrole-based π-spacer, has been synthesized as a suitable alternative to 2,2’,7,7’-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9’-spirobifluorene ( Spiro-OMeTAD ), considered the benchmark hole transporting material (HTM) in perovskite solar cells (PSCs). The cheap synthetic protocol is suitable for potential large-scale production. All the compounds were characterized, showing good energy levels alignments with the perovskite and very close energy levels to the Spiro-OMeTAD . Furthermore, computational analysis confirmed the electrochemical trend observed. The costs of synthesis were estimated, as well as the produced waste to synthesise the final HTMs, underlining the low impact of these compounds on the environment with the respect to Spiro-OMeTAD . Overall, the relevant electrochemical properties and the low cost of the synthetic approaches allow these compounds to be a greener and easy-to-synthesize alternative to the Spiro-OMeTAD for industrial development of PSCs.     

D-π-A-π-D型非掺杂小分子空穴传输材料的合成及其在反向钙钛矿太阳能电池中的应用

设计合成了三种以（甲氧基）三苯胺为给体（Donor,D）,苯环为共轭π桥,羰基（或双氰基乙烯基）为受体（Acceptor,A）的D-π-A-π-D型有机小分子空穴传输材料1-T、1-OT和1-OTCN.对三个化合物的热稳定性、光物理以及电化学性质进行表征,并将它们作为空穴传输材料运用至钙钛矿太阳能电池中,研究其光伏特性.实验结果表明,通过引入具有不同给（吸）电子能力的基团,可对材料的光电性质进行有效调控.基于小分子空穴传输材料1-T、1-OT和1-OTCN的非掺杂反向钙钛矿太阳能电池器件光电转化效率（PCE）分别为13.0%、14.4%以及16.8%.其中,基于甲氧基和双氰基修饰的1-OTCN电池器件,由于空穴传输层与钙钛矿界面发生更有效的电荷跃迁和收集,电荷复合较少,因此器件性能最佳,1-OTCN的疏水性质使得其对应器件效率和水氧稳定性均优于常用空穴传输材料PEDOT：PSS（PCE：13.0%）.     

芳香族腙类空穴传输材料的合成及其光电性能研究

芳香族腙类空穴传输材料的合成及其光电性能研究;腙;合成;芳醛;空穴传输材料     

Molecular engineering of inorganic halide perovskites and HTMs for photovoltaic applications

A comprehensive study was performed for the design of ABX₃ perovskites, (A = Li, K, Na, B = Ge, Sn, Pb, X = F, Cl, Br, I) and organic hole transfer materials, HTMs (Fu-2a, Fu-2b, Fu-2c, and Dm-Q) for efficient perovskite solar cells (PSCs) through quantum chemistry calculations. Photovoltaic characteristics of the investigated perovskites are strongly affected by the halide anions. The results reveal that reducing the exciton binding energy of perovskites enhances the rate of the formation/dissociation of holes and electrons so F-based perovskites are superior from this viewpoint. Additionally, the electron and hole injection processes are more favorable in the case of the F-based perovskites in comparison with other studied perovskites. Moreover, spectroscopic properties of the perovskites demonstrate that KSnCl₃, NaSnCl₃, and F-based perovskites exhibit a greater ability of the light-harvesting and incident photon to current conversion efficiency. Ultimately, based on diverse analyses, F-based perovskites, KSnCl₃ and NaSnCl₃ are the preferred candidates to be applied in the PSCs due to an excellent incident photon to current conversion efficiency, light-harvesting efficiency, short circuit current, and solar cell final efficiency.     

Minimization of Carrier Losses for Efficient Perovskite Solar Cells through Structural Modification of Triphenylamine Derivatives

Three hole transport materials (HTMs) based on a substituted triphenylamine moiety have been synthesized and successfully employed in triple‐cation mixed‐halide PSCs, reaching efficiencies of 19.4 %. The efficiencies, comparable to those obtained using spiro‐OMeTAD, point them out as promising candidates for easily attainable and cost‐effective alternatives for PSCs, given their facile synthesis from commercially available materials. Interestingly, although all these HTMs show similar chemical and physical properties, they provide different carrier recombination kinetics. Our results demonstrate that is feasible through the molecular design of the HTM to minimize carrier losses and, thus, increase the solar cell efficiencies.     

钙钛矿太阳电池电子传输层与光吸收层的界面工程

钙钛矿太阳电池(PSCs)自2009年出现至今经历了光伏领域前所未有的快速发展,目前经认证的最高光电转换效率已超过23%,极具应用前景。界面工程是提升PSCs性能的有效途径之一,本文回顾了PSCs中电子传输层和钙钛矿光吸收层间界面工程的主要研究工作,根据作用效果将相关研究按照改善钙钛矿光吸收层质量、提高电子传输层与钙钛矿层间的能级匹配度和提升电池稳定性等三类进行了梳理和总结,并对电子传输层和钙钛矿光吸收层间界面工程的前景进行了展望。     

掺杂PEDOT：PSS空穴传输层在钙钛矿太阳能电池中的应用

钙钛矿太阳能电池(PSCs)因易于制备、生产成本低和能量转换效率高而受到广泛关注。聚乙撑二氧噻吩-聚(苯乙烯磺酸盐)(PEDOT∶PSS)由于具有易低温加工、透光度高和适宜空穴迁移率等特点而成为PSCs中空穴传输层的研究热点。本文简述了倒置PSCs的结构及工作原理,重点介绍了掺杂PEDOT∶PSS空穴传输层在PSCs领域的研究现状。分别从有机化合物掺杂剂、无机化合物掺杂剂和表面活性剂掺杂剂三个类别概述了掺杂PEDOT∶PSS空穴传输层对PSCs性能的影响。最后,对该领域存在的问题提出潜在措施以改善PEDOT∶PSS掺杂层在PSCs中的应用。     

反式钙钛矿电池超薄空穴传输层研究进展

空穴传输层(HTLs)厚度对反式钙钛矿太阳能电池(PSCs)性能具有重大影响,因其显著影响太阳光透过和HTLs的空穴传输性能。几个纳米至十几个纳米厚度的超薄HTLs在减少伴生吸收、电荷传输损失和材料消耗等方面具有明显优势。目前,有许多成熟的制备超薄无机HTLs的方法,并在反式和叠层PSCs中得到广泛研究与应用。最近,一些关于有机超薄HTLs的新型制备方法也展现出良好的性能并逐渐引起相关领域研究者关注。在此,本文主要总结反式PSCs中超薄HTLs的研究进展与应用,关注其未来发展的挑战和方向,为该领域进一步的研究提供参考。     

钙钛矿太阳能电池中小分子空穴传输材料的研究进展

有机-无机钙钛矿太阳能电池(PSCs)从2009年低于5%的能量转换效率到现在经过认证的超过22%的效率,成为科研热点和最有希望商业化的新型太阳能电池。在高性能的PSCs中,空穴传输材料是关键的一环,起到从钙钛矿活性层材料到对电极有效抽取和传输空穴的作用。本文在现有研究成果的基础上,对有机分子空穴传输材料在PSC中的应用进行总结,并强调分子材料结构对PSC器件性能(效率和稳定性)的影响。     

Ultrafast Photogenerated Hole Extraction/Transport Behavior in a CH3NH3PbI3/Carbon Nanocomposite and Its Application in a Metal‐Electrode‐Free Solar Cell

Aligned and flexible electrospun carbon nanomaterials are used to synthesize carbon/perovskite nanocomposites. The free‐electron diffusion length in the CH₃NH₃PbI₃ phase of the CH₃NH₃PbI₃/carbon nanocomposite is almost twice that of bare CH₃NH₃PbI₃, and nearly 95 % of the photogenerated free holes can be injected from the CH₃NH₃PbI₃ phase into the carbon nanomaterial. The exciton binding energy of the composite is estimated to be 23 meV by utilizing temperature‐dependent optical absorption spectroscopy. The calculated free carriers increase with increasing total photoexcitation density, and this broadens the potential of this material for a broad range of optoelectronics applications. A metal‐electrode‐free perovskite solar cell (power conversion efficiency: 13.0 %) is fabricated with this perovskite/carbon composite, which shows great potential for the fabrication of efficient, large‐scale, low‐cost, and metal‐electrode‐free perovskite solar cells.     

Control of Charge Transport in the Perovskite CH3NH3PbI3 Thin Film

Carrier density and transport properties in the CH₃NH₃PbI₃ thin film have been investigated. It is found that the carrier density, the depletion field, and the charge collection and transport properties in the CH₃NH₃PbI₃ absorber film can be controlled effectively by different concentrations of reactants. That is, the carrier properties and the self‐doping characteristics in CH₃NH₃PbI₃ films are strongly influenced by the reaction thermodynamic and kinetic processes. Furthermore, by employing mixed solvents with ethanol and isopropanol to deposit the CH₃NH₃PbI₃ film, the charge collection and transport efficiencies are improved significantly, thereby yielding an overall enhanced cell performance.     

钙钛矿太阳电池研究进展:薄膜形貌控制与界面工程

有机-无机杂化钙钛矿太阳电池因兼具低成本溶液加工和优异的光电转换性能在国际上倍受关注. 基于其吸收强、迁移率高、载流子寿命长、可调控带隙以及可采用多种方式加工等优势, 钙钛矿太阳电池在短短5年时间里, 实验室小面积器件的能量转换效率已经从低于5%提高到近20%, 模块器件的能量转换效率可达8.7%, 其效率超过了很多其他类型太阳电池, 接近可以商业化的水平. 借助于相关材料性质理解和电池设计优化, 钙钛矿太阳电池效率的进一步提升存在很大的潜力空间. 本文通过文献综述, 在回顾国内外钙钛矿太阳电池发展情况的基础上, 着重讨论影响钙钛矿太阳电池性能的其中两个重要因素: 薄膜形貌控制与界面工程, 并分析了钙钛矿太阳电池面临的基础科学问题以及展望该技术的未来前景.     

压强对钙钛矿薄膜形貌和结晶性影响的研究

采用新型简便的方法控制钙钛矿层薄膜的结晶过程,对优化制备工艺、获得高性能器件至关重要。本文采用调节真空度的方法有效控制钙钛矿层结晶,系统地研究了压强的作用及其对晶体生长、薄膜形成及器件性能的影响。采用扫描电子显微镜(SEM)、紫外-可见吸收光谱、X射线衍射光谱(XRD)谱图等手段对钙钛矿层的形貌及结晶程度进行了分析表征。在此基础上,制备出器件结构为Glass/ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Al的钙钛矿太阳能电池,考察了不同压强下的器件性能。结果表明:随压强降低,钙钛矿层结晶程度明显提高,孔洞减少,表面覆盖率提高。同时,器件的短路电流、填充因子以及光电转化效率均随压强降低而提高,器件效率由原来的10.38%提高到12.36%,提高了19%。     

Molecular Aggregation of Naphthalene Diimide(NDI) Derivatives in Electron Transport Layers of Inverted Perovskite Solar Cells and Their Influence on the Device Performance

One of key factors to design applicable electron transport layers (ETLs) for perovskite solar cells is the morphology of ETLs since a good morphology would help to facilitate the carrier transport at two interfaces (perovskite\ETL and ETL\cathode). However, one drawback of most organic ETL small molecules is the internal undesired accumulation, which would cause the formation of inappropriate morphology and rough ETL surface. Here, by elaborately designing the side chains of NDI derivatives, the molecular interaction could be modified to achieve the aggregation in different degrees, which would eventually affect the accumulation of molecules and surface qualities of ETLs. By speculating from the comparison between the absorption spectra of solutions and films, the sequence of extent of molecule interaction and aggregation was built among three NDI derivatives, which is further confirmed by direct evidence of atomic force microscopy (AFM) images. Then, carrier exaction abilities are simply studied by steady‐state photoluminescence spectroscopy. The carrier transport process is also discussed based on cyclic voltammetry, time‐resolved photoluminescence spectroscopy and mobility. NDIF1 are proven to have the appropriate internal aggregation to smooth the contact with cathode and low series resistance, and a device performance of 15.6 % is achieved. With the ability of preventing the thermal diffusion of Ag towards the perovskite surface due to the strong interaction between molecules, NDIF2 at high concentration shows the highest fill factor (80 %).