基于吡嗪空穴传输层的合成及在p-i-n型钙钛矿太阳能电池中的应用

钙钛矿太阳能电池由于具有高的光电转换效率,简单的溶液加工工艺,较低的成本等优势因而拥有广阔的应用前景。有机小分子空穴传输层材料在钙钛矿太阳能电池中扮演着极其重要的角色。在本工作中,我们设计和合成了基于吡嗪为分子中心核,三苯胺为分枝的X型空穴传输层材料PT-TPA。与Si-OMeTPA对比,吡嗪的引入不仅不会影响其结晶性,并且能够改善其电荷转移特性和分子中心共平面性,从而显著提升了PT-TPA的空穴迁移率。在非掺杂的情况之下,基于PT-TPA空穴传输层的p-i-n型钙钛矿太阳能电池展现出17.52%的光电转换效率,与相同条件下基于Si-OMeTPA空穴传输层的器件相比,效率提高了近15%。     

基于WOx/PEDOT:PSS复合空穴传输层的高效稳定平面异质结钙钛矿太阳电池

在基于钙钛矿/富勒烯平面异质结的钙钛矿太阳电池中,PEDOT:PSS是最常使用的空穴传输材料. 但PEDOT:PSS呈酸性,会腐蚀金属氧化物透明电极,使器件的电极界面稳定性欠佳. 本文将高功函的氧化钨（WO_x）插入到PEDOT:PSS和FTO之间,形成WO_x/PEDOT:PSS复合空穴传输层,这样既可以避免PEDOT:PSS与FTO直接接触,提高器件的稳定性,又可以进一步降低电极界面的接触势垒,从而提升器件的性能. 作者研究了复合传输层对透光率、钙钛矿形貌、钙钛矿结晶、光伏性能及器件稳定性的影响. 基于WO_x/PEDOT:PSS复合空穴传输层的电池效率可以达到12.96%,比单纯的PEDOT:PSS的电池效率(10.56%)提升了22.7%,同时器件的稳定性也得到大幅改善.     

界面修饰策略在钙钛矿太阳能电池中的应用

目前钙钛矿太阳能电池的认证效率已达25.2%,被认为是下一代最有希望的薄膜太阳能电池候选者。但通过溶液加工方法制备的钙钛矿薄膜不可控的形貌与较差的结晶性是制约器件稳定性提升和大面积生产的主要原因。为了有效解决这一难题,研究者们通常在电荷传输层与钙钛矿层之间进行界面修饰。本文从界面修饰的角度出发,总结了不同界面修饰策略在钙钛矿太阳能电池中的应用,并展望了界面修饰在低成本和大面积钙钛矿太阳能电池的应用前景。     

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...     

左旋多巴和N,N-二甲基亚砜共掺杂PEDOT:PSS作为空穴传输层的高性能p-i-n型钙钛矿太阳能电池

在p-i-n型的钙钛矿太阳能电池中,聚3, 4-乙烯二氧噻吩：聚苯乙烯磺酸盐(PEDOT:PSS)作为最常用的空穴传输层(HTL)材料之一,由于其存在着吸湿性强以及能级与钙钛矿层不匹配等缺点,限制了它的应用。基于此,本文拟采用将左旋多巴(DOPA)和N, N-二甲基亚砜(DMSO)共同掺杂于PEDOT:PSS作为HTL的简单方法制备高性能p-i-n型钙钛矿太阳能电池。研究结果表明,DOPA和DMSO共掺杂PEDOT:PSS可以有效的调节HTL的能级并提高其导电性,器件的能量转化效率由13.35%显著提高到了17.54%。进一步研究发现,相比于未掺杂或单一掺杂的PEDOT:PSS,在DOPA和DMSO共掺杂的PEDOT:PSS上更有利于生长大尺寸、高结晶度的钙钛矿晶体;同时稳态/瞬态荧光和交流阻抗测试表明器件的内部载流子分离和传输更加有效。     

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。     

低成本富勒烯衍生物电子传输层在钙钛矿太阳能电池的应用

Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted significant attention owing to their high absorption coefficient and ambipolar charge transport properties. With only several years of development, the power conversion efficiency (PCE) has increased from 3.8% to 22.7%. In general, PSCs have two types of structural architecture: mesoporous and planar. The latter possesses higher potential for commercialization due to its simpler structure and fabrication process, especially the inverted planar structure, which possesses negligible hysteresis. In an inverted PSC, the electron transport materials (ETM) are deposited on a perovskite film. Only a few ETMs can be used for inverted PSCs as the perovskite film is easily damaged by the solvent used to dissolve the ETM. Furthermore, the energy levels of the ETM should be well aligned with that of the perovskites. Normally it is difficult to use inorganic ETMs as they require high temperatures for the annealing process to improve the electron conductivity; the perovskite film cannot sustain these high temperatures. To date, the fullerene derivative, [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM), is the most commonly used organic ETM for high efficiency inverted planar PSCs. However, the high manufacturing cost due to its complex synthesis retards the industrialization of the PSCs. Here, we introduce a fullerene pyrrolidine derivative, N-methyl-2-pentyl-[60]fullerene pyrrolidine (NMPFP), synthesized via the Prato reaction of C₆₀ directly with cheap hexanal and sarcosine. Then the NMPFP electron transport layer (ETL) was prepared by a simple solution process. The properties of the resulting NMPFP ETLs were characterized using UV-Vis absorption spectroscopy, cyclic voltammetry measurements, atomic force microscopy, and conductivity test. From the results of the UV-Vis absorption spectroscopy and cyclic voltammetry measurements, the LUMO level of NMPFP ETL was calculated to be 0.2 eV higher than that of the PCBM ETL. This contributes to a higher open-circuit photovoltage. In addition, the NMPFP film presented higher conductivity than the PCBM film. Thus, the photo-generated charge carriers in the perovskite films should be transported more efficiently to the NMPFP electron transport layer (ETL) than to the PCBM ETL. This was confirmed by the results of the steady-state photoluminescence spectroscopy. Finally, the NMPFP as an alternative low-cost ETL was employed in an inverted planar PSC to evaluate the device performance. The device made with the NMPFP ETL yielded an efficiency of 13.83% with negligible hysteresis, which is comparable to the PCBM counterpart devices. Moreover, since stability is another important parameter retarding the commercialization of PSCs, the stability of the PCBM and NMPFP base PSCs were investigated and compared. It was found that the NMPFP devices possessed significantly improved stability due to the higher hydrophobicity of the NMPFP. In conclusion, this research demonstrates that NMPFP is a promising ETL to replace PCBM for the industrialization of cheap, efficient and stable inverted planar PSCs.     

自组装单分子空穴传输层在反式钙钛矿太阳电池的研究进展

空穴传输层在钙钛矿太阳电池(Perovskite solar cell, PSC)中起着抽取和传输钙钛矿层产生的光生空穴、抑制电子回流等重要作用,是构成高性能器件的重要组成部分.经典的空穴传输材料,如2,2’,7,7’-四[N,N-二(4-甲氧基苯基)氨基]-9,9’-螺二芴(spiro-OMe TAD)、聚[双(4-苯基)(2,4,6-三甲基苯基)胺](PTAA)等,空穴迁移率低、价格昂贵等缺点限制了其规模化应用.近年来,在反式PSC中自组装单分子层(self-assembledmonolayers,SAM)作为空穴传输层广泛应用,提升了器件性能.SAM分子结构中含有锚定官能团,可以在衬底上形成单分子薄膜,有着材料消耗小、无需添加剂、寄生吸收低、能够兼容叠层器件和有利于大面积制造等优点,已成为PSC领域的研究热点.本综述结合PSC发展,按照SAM分子结构中锚定基团的不同,对近年来基于SAM的空穴传输层的研究进行了分类和归纳,结合分子骨架变化分析了结构变化对其特性及器件性能的影响.最后,对SAM作为空穴传输层的发展做了总结和展望.     

低成本、高性能钙钛矿电池有机小分子空穴传输材料

钙钛矿太阳能电池由于其高能量转换效率(最高报道认证效率为25.2％)、低成本和易于制造等特点,成为下一代光伏技术的关注焦点.虽然钙钛矿材料本身可以传导空穴,但其效率比较低.空穴传输材料的使用成为有效提取电荷和提高钙钛矿型太阳能电池效率的关键因素.总结了近期报道的低成本、高性能有机小分子空穴传输材料(效率大于19％),从...     

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.     

ZnO电极修饰层在钙钛矿太阳能电池中的应用

ZnO电极修饰层具有高电子迁移率、高透光率、可低温制备且环境友好等优点在钙钛矿太阳能电池上获得了广泛应用。本文针对传统电极修饰层需要高温退火、透光率较低、制备过程繁琐,不利于高性能柔性钙钛矿电池器件制备等问题,系统综述了以ZnO材料作为电极修饰层的制备方法,综合分析了ZnO构筑的电极修饰层形貌、厚度、掺杂及复合对钙钛矿太阳能电池性能（如开路电压、电流密度、填充因子、光电转换效率等）的影响,展望了ZnO电极修饰层材料的未来发展趋势与其在钙钛矿太阳能电池中的应用前景。     

An Azaacene Derivative as Promising Electron‐Transport Layer for Inverted Perovskite Solar Cells

It is highly desirable to develop novel n‐type organic small molecules as an efficient electron‐transport layer (ETL) for the replacement of PCBM to obtain high‐performance metal‐oxide‐free, solution‐processed inverted perovskite solar cells (PSCs) because this type of solar cells with a low‐temperature and solution‐based process would make their fabrication more feasible and practical. In this research, the new azaacene QCAPZ has been synthesized and employed as non‐fullerene ETL material for inverted PSCs through a solution‐based process without the need for additional dopants or additives. The as‐fabricated inverted PSCs show a power conversion efficiency up to 10.26 %. Our results clearly suggest that larger azaacenes could be promising electron‐transport materials to achieve high‐performance solution‐processed inverted PSCs.     

Lithium Polystyrene Sulfonate as a Hole Transport Material in Inverted Perovskite Solar Cells

Despite the exceptional efficiency of perovskite solar cells (PSCs), further improvements can be made to bring their power conversion efficiencies (PCE) closer to the Shockley-Queisser limit, while the development of cost-effective strategies to produce high-performance devices are needed for them to reach their potential as a widespread energy source. In this context, there is a need to improve existing charge transport layers (CTLs) or introduce new CTLs. In this contribution, we introduced a new polyelectrolyte (lithium poly(styrene sulfonate (PSS))) (Li:PSS) polyelectrolyte as an HTL in inverted PSCs, where Li⁺ can act as a counter ion for the PSS backbone. The negative charge on the PSS backbone can stabilize the presence of p-type carriers and p-doping at the anode. Simple Li:PSS performed poorly due to poor surface coverage and voids existence in perovskite film as well as low conductivity. PEDOT:PSS was added to increase the conductivity to the simple Li:PSS solution before its use which also resulted in lower performance. Furthermore, a bilayer of PEDOT:PSS and Li:PSS was employed, which outperformed simple PEDOT:PSS due to high quality of perovskite film with large grain size also the large electron injection barrier (ϕ_e) impeded back diffusion of electrons towards anode. As a consequence, devices employing PEDOT:PSS / Li:PSS bilayers gave the highest PCE of 18.64%.     

Metallated Macrocyclic Derivatives as a Hole – Transporting Materials for Perovskite Solar Cells

Spiro‐OMeTAD is widely used as thehole‐transporting material (HTM) in perovskite solar cells (PSC), which extracts positive charges and protects the perovskite materials from metal electrode, setting a new world‐record efficiency of more than 20 %. Spiro‐OMeTAD layer engross moisture leading to the degradation of perovskite, and therefore, has poor air stability. It is also expensive therefore limiting scale‐up, so macrocyclic metal complex derivatives (MMDs) could be a suitable replacement. Our review covers low‐cost, high yield hydrophobic materials with minimal steps required for synthesis of efficient HTMs for planar/mesostructured PSCs. The MMDs based devices demonstrated PCEs around 19 % and showed stability for a longer duration, indicating that MMDs are a promising alternative to spiro‐OMeTAD and also easy to scale‐up via solution approach. Additionally, this review describes how optical and electrical properties of MMDs change with chemical structure, allowing for the design of novel hole‐mobility materials to achieve negligible hysteresis and act as effective functional barriers against moisture which results in a significant increase in the stability of the device. We provide an overview of the apt green‐synthesis, characterization, stability and implementation of the various classes of macrocyclic metal complex derivatives as HTM for photovoltaic applications.     

Enhanced Photovoltage for Inverted Perovskite Solar Cells Using Delafossite CuCrO2 Hole Transport Material

Poly(3, 4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) has been widely adopted as hole transport material (HTM) in inverted perovskite solar cells (PSCs), due to high optical transparency, good mechanical flexibility, and high thermal stability; however, its acidity and hygroscopicity inevitably hamper the long-term stability of the PSCs and its energy level does not match well with perovskite materials with a relatively low open-circuit voltage. In this work, p-type delafossite CuCrO\begin{document}$ _2 $\end{document} nanoparticles synthesized through hydrothermal method was employed as an alternative HTM for triple cation perovskite [(FAPbI\begin{document}$ _3 $\end{document})\begin{document}$ _{0.87} $\end{document}(MAPbBr\begin{document}$ _3 $\end{document})\begin{document}$ _{0.13} $\end{document}]\begin{document}$ _{0.92} $\end{document}(CsPbI\begin{document}$ _3 $\end{document})\begin{document}$ _{0.08} $\end{document} (possessing better photovoltaic performance and stability than conventional CH\begin{document}$ _3 $\end{document}NH\begin{document}$ _3 $\end{document}PbI\begin{document}$ _3 $\end{document}) based inverted PSCs. The average open-circuit voltage of PSCs increases from 908 mV of the devices with PEDOT: PSS HTM to 1020 mV of the devices with CuCrO\begin{document}$ _2 $\end{document} HTM. Ultraviolet photoemission spectroscopy demonstrates the energy band alignment between CuCrO\begin{document}$ _2 $\end{document} and perovskite is better than that between PEDOT: PSS and perovskite, the electrochemical impedance spectroscopy indicates CuCrO\begin{document}$ _2 $\end{document}-based PSCs exhibit larger recombination resistance and longer charge carrier lifetime than PEDOT: PSS-based PSCs, which contributes to the high \begin{document}$ V_{\rm{OC}} $\end{document} of CuCrO\begin{document}$ _2 $\end{document} HTM-based PSCs.     

Star‐Shaped Molecules as Dopant‐Free Hole Transporting Materials for Efficient Perovskite Solar Cells: Multiscale Simulation

On the reported TCP‐OH (See Scheme 1), other two star‐shaped molecules are theoretically designed by replacement of side group of TCP‐OH by N,N‐di(4‐methoxyphenyl)aniline for TPAP‐OH and oxygen‐bridged triarylamine for TBOPP‐OH . The core group, phenol, is kept in three molecules. Their potential to be hole transport material in perovskite solar cells without dopants is evaluated by multiscale simulations. The properties of isolated molecules are estimated by the frontier molecular orbital, absorption spectrum, and hole mobility. After that, the HTM@CH₃NH₃PbI₃ adsorbed system is studied to consider the influence of adsorption on HTM performance. Besides the primary judgment, the glass transition temperature is also simulated to determine the stability of amorphous film. Not only the chemical stability is evaluated but also the amorphous film stability is considered. The latter is almost neglected in previous theoretical studies to evaluate the properties of HTMs. The performance of a designed molecule is evaluated from both the isolated molecules and HTM@CH₃NH₃PbI₃ adsorbed system including aforementioned items, which is favorable to build reliable structure‐property relationship.     

钙钛矿太阳能电池中吸收层的研究进展

钙钛矿太阳能电池因具有成本低、制备容易和光电性能优异等突出特点受到了广泛关注.钙钛矿太阳能电池能量转化效率已从2009年的3.8%提升到2019年的25.2%.我们在文中重点总结了钙钛矿电池吸收层的制备工艺,掺杂和晶体组成、结构调控方面取得的重要进展,以及这些突破对电池效率提高的贡献,同时也提出了钙钛矿太阳能电池发展仍需要解决的问题.     

A Multifunctional Liquid Crystal as Hole Transport Layer Additive Enhances Efficiency and Stability of Perovskite Solar Cells

Lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) has been identified as the most used and effective p-dopant for hole transport layer (HTL) in perovskite solar cells (PSCs). However, the migration and agglomeration of Li-TFSI in HTL negatively impact PSCs performance and stability. Herein, we report an effective strategy for adding a liquid crystal organic small molecule (LQ) into Li-TFSI doped (2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′- spirobifluorene (Spiro-OMeTAD) HTL. It was found that the introduction of LQ into Spiro-OMeTAD HTL can efficiently enhance the charge carrier extraction and transportation in device, which can strongly retard the charge carrier recombination in device. Consequently, the PSCs efficiency is significantly enhanced to 24.42 % (Spiro-OMeTAD+LQ) from 21.03 % (Spiro-OMeTAD). The chemical coordination between LQ and Li-TFSI can strongly confine Li⁺ ions migration and agglomeration of Li-TFSI, thus, achieving the enhanced device stability. Only a 9 % efficiency degradation is observed for un-encapsulated device prepared with Spiro-OMeTAD and LQ after 1700 h under air environment, while the efficiency drops by 30 % for the reference device. This work provides an effective strategy for improving the efficiency and stability of PSCs, and gives some important insights for understanding intrinsic hot carriers dynamics for perovskite-based optoelectronic devices.