基于印刷技术制备钙钛矿太阳电池

近年来,钙钛矿太阳电池(Perovskite solar cells,PSCs)以其优异的光电转换性能和溶液制备成本低等优势受到了科研工作者和产业界人士的广泛关注,被认为是新一代薄膜太阳电池技术中的杰出代表。目前,钙钛矿太阳电池的光电转换效率(Power conversion efficiency,PCE)已经从2009年报道的3.8%迅速提升到现在的22.7%,达到商业化多晶硅、碲化镉、铜铟镓硒等太阳电池水平。目前,溶液旋涂法是实验室制备钙钛矿太阳电池的常用方法。虽然旋涂法操作简单、成膜速度快、重复性好,然而该法缺点也很明显:(1)材料浪费严重;(2)不具备图案化功能;(3)不适用于工业化的连续生产。因此,溶液旋涂技术无法满足钙钛矿太阳电池今后大规模工业化生产所需的大面积、低成本等制造要求。从实验室小面积器件制备转变到可大面积的产业化制备以及降低钙钛矿太阳电池的生产成本,将是钙钛矿太阳电池产业化过程中的一个重要课题。在钙钛矿太阳电池的制备方法中,印刷技术因具有材料利用率高、成本低、工艺效率高、可大面积制备、适用于柔性基底等特点而备受关注。基于印刷工艺制备的小面积钙钛矿太阳电池效率已接近20%,大面积(10cm2)钙钛矿太阳电池效率在10%～16%之间,大面积柔性钙钛矿太阳电池效率为10%左右。然而,从实验室小器件转变到大规模工业化生产依旧存在许多问题亟待解决。例如:(1)为了加快钙钛矿材料的结晶,在钙钛矿薄膜退火过程中通常采用溶剂工程或惰性气体辅助的方式,这将导致印刷的大面积钙钛矿薄膜质量难以控制以及重复性降低;(2)退火过程中较高的退火温度会限制柔性基底和界面材料的选择;(3)钙钛矿材料本身对空气湿度敏感,需提高钙钛矿层制备过程的环境适应性,降低制备工艺本身对环境条件的限制等。基于此,完善钙钛矿太阳电池的印刷制备工艺并使其适用于工业化生产显得十分重要。本文综述了基于喷墨打印(Inkjet-printing)、喷涂(Spray-coating)、狭缝涂布(Slot-die coating)、刮涂(Doctor-blading)等印刷技术制备钙钛矿太阳电池的研究进展,并对印刷技术制备钙钛矿太阳电池的前景进行了展望。     

基于形核结晶调控的钙钛矿太阳电池印刷制造的研究进展

目的 有机–无机杂化钙钛矿太阳电池以其优异的光电转换性能和低成本溶液加工等优势受到了科研工作者和产业界人士的广泛关注,文中着眼于解决把实验室的旋涂研发工艺转换为可大规模重复生产的工艺这一直接挑战。方法 印刷制造技术具有低成本、大规模、高产率、适用于柔性基底等优点,是应对该挑战的有效手段。深入梳理和总结印刷制造中钙钛矿薄膜的形核与结晶过程,对于印刷高质量钙钛矿薄膜和实现大面积高效钙钛矿太阳电池制造至关重要。结论 分析了钙钛矿形核结晶的热力学与动力学基本理论,从钙钛矿形核结晶调控这一角度出发,对各类印刷工艺制造大面积钙钛矿薄膜及光伏器件的研究现状做出相应评价,认为“升级制备技术、创新材料体系、改善稳定性能”三步走将掀起钙钛矿产业化的新浪潮。     

大面积钙钛矿薄膜制备技术的研究进展

有机-无机杂化钙钛矿太阳能电池因其较高的光电转换效率和较低的生产成本而备受关注.其优异的光电性能主要归因于该类钙钛矿材料的光吸收系数高、载流子迁移率高、载流子寿命长、带隙可调等物理特性;由于其可基于溶液加工法进行规模化生产,使其生产成本大幅降低,并快速成为新型薄膜太阳能电池新星.在过去十年的时间里,钙钛矿太阳能电池小面积器件(<1 cm2)的光电转换效率已经从2009年的3.8％迅速飙升至25.2％;而其小模块级组件(10～800 cm2)效率已提升至18.04％;模块级组件(>800 cm2)的光电转换效率也已经刷新到16.1％.小面积器件和模块级组件效率失配的关键因素之一是高质量、高均一性的大面积钙钛矿薄膜沉积方法的局限性.小面积器件钙钛矿成膜通常使用的是溶液旋涂法;但是,溶液旋涂法存在厚度不均匀、原料浪费严重等缺点,因而不适合用于制备大面积钙钛矿薄膜.当前,大面积钙钛矿薄膜的沉积方案处于多样化的研究当中,尚未形成稳定的工业化生产规模.迄今为止,主要报道的大面积钙钛矿薄膜的制备方法主要有:刮刀涂布法、狭缝涂布法、喷涂法、喷墨打印法、软覆盖沉积法、气相沉积法.本文归纳总结了近期大面积钙钛矿薄膜制备方法的研究进展;并对其基本原理进行分析与讨论,对比了各种大面积钙钛矿薄膜制备方法的优缺点;展望了它们在未来研究和产业化过程所面临的问题及其发展前景;旨在加深读者对大面积钙钛矿薄膜的沉积方法的理解,以期为大面积、高效率钙钛矿模组的研究与开发提供有益的参考.     

钙钛矿太阳能电池的产业化:丝网印刷钙钛矿

<正>钙钛矿太阳能电池具有优异的光电性能和溶液可加工的特性,其光电转换效率已超过 25%^[1]。钙钛矿薄膜的制备方法包括旋涂法、刮刀涂布法、喷涂法、开槽印刷法以及喷墨印刷法^[2-3]。与其他薄膜制造技术相比,丝网印刷具备可灵活图案印刷、高生产率和低成本生产等优点。因此,丝网印刷技术被认为是钙钛矿太阳能电池产业化的理想技术^[4]。     

两步旋涂沉积条件对钙钛矿薄膜形貌和电池性能的影响研究

钙钛矿薄膜的制备条件和生长过程对其太阳电池性能有着至关重要的影响。基于两步旋涂法,采用4种不同的薄膜工艺制备了平面异质结型钙钛矿太阳电池,系统地研究了CH3NH3PbI3薄膜形貌对于太阳电池性能的影响。实验发现,PbI_2溶液的溶剂成分以及CH_3NH_3I溶液的浓度对于生成的CH_3NH_3PbI_3光活性层形貌和太阳电池性能有着显著影响。相比于纯的N,N-二甲基甲酰胺(DMF),采用DMF/二甲基亚砜(DMSO)的混合溶剂配制PbI_2溶液,获得的钙钛矿薄膜层更加平整致密,器件性能更高且性能的重现性更好。通过制备条件的优化,得到了14.2%的最佳能量转换效率。此外还分析了器件伏-安(J-V)特性测量中出现的回滞现象及其可能原因,并发现在空穴层传输层和金电极间插入6nm MoO_3层能够显著地抑制J-V回滞效应。     

大面积有机–无机杂化钙钛矿薄膜及其光伏应用研究进展

有机–无机杂化钙钛矿太阳能电池具有制备成本低、光电转换效率(Photoelectric Conversion Efficiency, PCE)高的巨大优势,显示出广阔的商业化前景。经过十几年的深入研究,钙钛矿太阳能电池(Perovskite Solar Cells, PSCs)的实验室器件(<1 cm2)、大面积器件(1～10 cm2)、迷你模组级器件(10～800 cm2)和模组级器件(>800 cm2)的最高认证PCE已分别提升至26.10%、24.35%、22.40%和18.60%。随着PSCs面积扩大,PCE急剧下降,这主要是因为制备方法的局限性,难以获得高质量的大面积钙钛矿薄膜。实验室器件常采用的旋涂法难以应用到实际生产中,目前大面积钙钛矿薄膜的制备方法主要有刮涂法和狭缝涂布法,但其存在薄膜成核结晶过程难以精确控制等问题。本文从大面积有机–无机杂化钙钛矿薄膜的制备方法入手,介绍了大面积钙钛矿层成膜机制及薄膜质量提升策略。最后,对未来高PCE、高稳定性的大面积PSCs的制备技术和应用进行了展望,旨在对高性能的大面积PSCs研究提供有益参考。     

NMP溶剂退火制备高效钙钛矿太阳电池

钙钛矿薄膜中的PbI2缺陷会引起载流子复合,降低电池性能。通过对一步法制备的钙钛矿薄膜进行NMP(N-甲基吡咯烷酮)溶剂退火,减少热处理过程中有机阳离子的损失,实现钙钛矿晶界处PbI2缺陷的减少,同时增大晶粒尺寸、实现薄膜粗糙度及起伏度的调控。结果表明NMP溶剂退火方法可抑制薄膜中的非辐射复合,降低缺陷态浓度,实现薄膜光吸收的增强,从而提高钙钛矿太阳电池的短路电流和填充因子。与未经过NMP溶剂退火处理的电池相比,该方法制备的钙钛矿太阳电池的平均效率提高10.51%,最高效率提高22.15%。     

单源热蒸发制备有机无机杂化CH3NH3PbI3薄膜及其性能表征

采用全真空单源热蒸发沉积技术直接制备钙钛矿太阳电池用有机无机杂化CH₃NH₃PbI₃薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量色散谱仪(EDS)和分光光度计对制备的CH₃NH₃PbI₃薄膜微结构、表面形貌、化学成分和光学性能进行表征分析, 并与非真空旋涂法制备的CH₃NH₃PbI₃薄膜性能进行比较。结果表明: 单源热蒸发法制备的CH₃NH₃PbI₃薄膜呈现单一的钙钛矿四方晶体结构, 且与蒸发源材料的晶体结构同源性高, 没有出现杂质相偏析; 对比旋涂法制备的CH₃NH₃PbI₃薄膜表面均匀致密平整, 且薄膜结晶度更高; 单源热蒸发法制备的CH₃NH₃PbI₃薄膜禁带宽度为1.57 eV, 符合钙钛矿太阳电池吸收层光学性能要求。     

TiO2形态对MAPbBr3太阳电池转化效率影响机制的研究

二氧化钛(TiO₂)是钙钛矿太阳电池中最常用的电子传输材料, 研究发现其形态对MAPbBr₃太阳电池的器件转化效率可产生直接影响。研究不同形态TiO₂对钙钛矿太阳电池转化效率的影响机制对进一步认识此类太阳电池的工作机理十分必要。本工作使用旋涂法制备了不同形态的TiO₂, 而后采用反溶剂室温结晶的方法在TiO₂基底上进一步制备MAPbBr₃(MA = CH₃NH₃)薄膜, 并通过X射线光电子能谱(XPS)详细研究了TiO₂与MAPbBr₃接触界面的能级位置关系。研究结果表明: 不同形态的TiO₂ 在与钙钛矿接触后形成的导带差异不同; 不同的导带能级差可直接影响MAPbBr₃钙钛矿电池中电子的传递与收集, 进而影响电池的转化效率。     

全印刷介观钙钛矿太阳电池研究进展

近年来钙钛矿太阳电池发展迅速,基于碳电极的全印刷介观钙钛矿太阳电池因制作成本低、工艺简单、可丝网印刷等优点备受关注。目前,全印刷介观钙钛矿太阳电池的最高转换效率为18.05%,极具发展潜力。本文主要总结了全印刷介观钙钛矿太阳电池近年来取得的部分最新进展,从太阳电池各功能层的界面修饰、薄膜掺杂、离子取代等出发,对光电转换效率的提升方法进行分析总结,最后对全印刷介观钙钛矿太阳电池的发展趋势进行展望。     

Critical review of recent progress of flexible perovskite solar cells

Perovskite solar cells (PSCs) have emerged as a ‘rising star’ in recent years due to their high-power conversion efficiency (PCE), extremely low cost and facile fabrication techniques. To date, PSCs have achieved a certified PCE of 25.2% on rigid conductive substrates, and 19.5% on flexible substrates. The significant advancement of PSCs has been realized through various routes, including perovskite composition engineering, interface modification, surface passivation, fabrication process optimization, and exploitation of new charge transport materials. However, compared with rigid counterparts, the efficiency record of flexible perovskite solar cells (FPSCs) is advancing slowly, and therefore it is of great significance to scrutinize recent work and expedite the innovation in this field. In this article, we comprehensively review the recent progress of FPSCs. After a brief introduction, the major features of FPSCs are compared with other types of flexible solar cells in a broad context including silicon, CdTe, dye-sensitized, organic, quantum dot and hybrid solar cells. In particular, we highlight the major breakthroughs of FPSCs made in 2019/2020 for both laboratory and large-scale devices. The constituents of making a FPSC including flexible substrates, perovskite absorbers, charge transport materials, as well as device fabrication and encapsulation methods have been critically assessed. The existing challenges of making high performance and long-term stable FPSCs are discussed. Finally, we offer our perspectives on the future opportunities of FPSCs in the field of photovoltaics.     

Constructing Additives Synergy Strategy to Doctor-Blade Efficient CH3NH3PbI3 Perovskite Solar Cells under a Wide Range of Humidity from 45% to 82%

Perovskite solar cells (PSCs) have emerged as one of the most promising and competitive photovoltaic technologies, and doctor-blading is a facile and robust deposition technique to efficiently fabricate PSCs in large scale, especially matching with roll-to-roll process. Herein, it demonstrates the encouraging results of one-step, antisolvent-free doctor-bladed methylammonium lead iodide (CH₃NH₃PbI_3, MAPbI₃) PSCs under a wide range of humidity from 45% to 82%. A synergy strategy of ionic-liquid methylammonium acetate (MAAc) and molecular phenylurea additives is developed to modulate the morphology and crystallization process of MAPbI₃ perovskite film, leading to high-quality MAPbI₃ perovskite film with large-size crystal, low defect density, and ultrasmooth surface. Impressive power conversion efficiency (PCE) of 20.34% is achieved for doctor-bladed PSCs under the humidity over 80% with a device structure of ITO/SnO₂/MAPbI₃/Spiro-OMeTAD/Ag. It is the highest PCEs for one-step solution-processed MAPbI₃ PSCs without antisolvent assistance. The research provides a facile and robust large-scale deposition technique to fabricate highly efficient and stable PSCs under a wide range of humidity, even with the humidity over 80%.     

Record Efficiency Stable Flexible Perovskite Solar Cell Using Effective Additive Assistant Strategy

Even though the power conversion efficiency (PCE) of rigid perovskite solar cells is increased to 22.7%, the PCE of flexible perovskite solar cells (F‐PSCs) is still lower. Here, a novel dimethyl sulfide (DS) additive is developed to effectively improve the performance of the F‐PSCs. Fourier transform infrared spectroscopy reveals that the DS additive reacts with Pb²⁺ to form a chelated intermediate, which significantly slows down the crystallization rate, leading to large grain size and good crystallinity for the resultant perovskite film. In fact, the trap density of the perovskite film prepared using the DS additive is reduced by an order of magnitude compared to the one without it, demonstrating that the additive effectively retards transformation kinetics during the thin film formation process. As a result, the PCE of the flexible devices increases to 18.40%, with good mechanical tolerance, the highest reported so far for the F‐PSCs. Meanwhile, the environmental stability of the F‐PSCs significantly enhances by 1.72 times compared to the device without the additive, likely due to the large grain size that suppresses perovskite degradation at grain boundaries. The present strategy will help guide development of high efficiency F‐PSCs for practical applications.     

钙钛矿太阳能电池:从高效率到稳定性

钙钛矿太阳能电池(Perovskite solar cells,PSCs)由于制备工艺简单、价格便宜、转换效率高、可制备柔性器件等优点引起广泛关注。近年来,钙钛矿太阳能电池的转换效率不断被刷新,迅速实现了对多晶硅太阳能电池的超越,使其具有巨大的商业潜力。然而,稳定性成为阻碍钙钛矿太阳能电池商业化的一大问题。介绍了钙钛矿太阳能电池的结构,综述了钙钛矿太阳能电池所取得的研究进展,总结了获得高效率钙钛矿太阳能电池的方法,重点分析了提高钙钛矿太阳能电池稳定性的策略,并指出钙钛矿太阳能电池的发展方向。     

Multifunctional Polymer-Regulated SnO2 Nanocrystals Enhance Interface Contact for Efficient and Stable Planar Perovskite Solar Cells

Perovskite solar cells (PSCs) have rapidly developed and achieved power conversion efficiencies of over 20% with diverse technical routes. Particularly, planar-structured PSCs can be fabricated with low-temperature (≤150 °C) solution-based processes, which is energy efficient and compatible with flexible substrates. Here, the efficiency and stability of planar PSCs are enhanced by improving the interface contact between the SnO₂ electron-transport layer (ETL) and the perovskite layer. A biological polymer (heparin potassium, HP) is introduced to regulate the arrangement of SnO₂ nanocrystals, and induce vertically aligned crystal growth of perovskites on top. Correspondingly, SnO₂–HP-based devices can demonstrate an average efficiency of 23.03% on rigid substrates with enhanced open-circuit voltage (V_OC) of 1.162 V and high reproducibility. Attributed to the strengthened interface binding, the devices obtain high operational stability, retaining 97% of their initial performance (power conversion efficiency, PCE > 22%) after 1000 h operation at their maximum power point under 1 sun illumination. Besides, the HP-modified SnO₂ ETL exhibits promising potential for application in flexible and large-area devices.     

Quasi‐Heteroface Perovskite Solar Cells

Perovskite solar cells (PSCs) have attracted unprecedented attention due to their rapidly rising photoelectric conversion efficiency (PCE). In order to further improve the PCE of PSCs, new possible optimization path needs to be found. Here, quasi‐heteroface PSCs (QHF‐PSCs) is designed by a double‐layer perovskite film. Such brand new PSCs have good carrier separation capabilities, effectively suppress the nonradiative recombination of the PSCs, and thus greatly improve the open‐circuit voltage and PCE. The root cause of the performance improvement is the benefit from the additional built‐in electric field, which is confirmed by measuring the external quantum efficiency under applied electric field and Kelvin probe force microscope. Meanwhile, an intermediate band gap perovskite layer can be obtained simply by combining a wide band gap perovskite layer with a narrow band gap perovskite layer. Tunability of the band gap is obtained by varying the film thicknesses of the narrow and wide band gap layers. This phenomenon is quite different from traditional inorganic solar cells, whose band gap is determined only by the narrowest band gap layer. It is believed that these QHF‐PSCs will be an effective strategy to further enhance PCE in PSCs and provide basis to further understand and develop the perovskite materials platform.     

A perspective on the recent progress in solution-processed methods for highly efficient perovskite solar cells

Perovskite solar cells (PSCs) were developed in 2009 and have led to a number of significant improvements in clean energy technology. The power conversion efficiency (PCE) of PSCs has increased exponentially and currently stands at 22%. PSCs are transforming photovoltaic (PV) technology, outpacing many established PV technologies through their versatility and roll-to-roll manufacturing compatibility. The viability of low-temperature and solution-processed manufacturing has further improved their viability. This article provides a brief overview of the stoichiometry of perovskite materials, the engineering behind various modes of manufacturing by solution processing methods, and recommendations for future research to achieve large-scale manufacturing of high efficiency PSCs.     

Magnetic Field-Assisted Interface Embedding Strategy to Construct 2D/3D Composite Structure for Stable Perovskite Solar Cells with Efficiency Over 24%

Perovskite solar cells (PSCs) based on 2D/3D composite structure have shown enormous potential to combine high efficiency of 3D perovskite with high stability of 2D perovskite. However, there are still substantial non-radiative losses produced from trap states at grain boundaries or on the surface of conventional 2D/3D composite structure perovskite film, which limits device performance and stability. In this work, a multifunctional magnetic field-assisted interfacial embedding strategy is developed to construct 2D/3D composite structure. The composite structure not only improves crystallinity and passivates defects of perovskite layer, but also can efficiently promote vertical hole transport and provide lateral barrier effect. Meanwhile, the composite structure also forms a good surface and internal encapsulation of 3D perovskite to inhibit water diffusion. As a result, the multifunctional effect effectively improves open-circuit voltage and fill factor, reaching maximum values of 1.246 V and 81.36%, respectively, and finally achieves power conversion efficiency (PCE) of 24.21%. The unencapsulated devices also demonstrate highly improved long-term stability and humidity stability. Furthermore, an augmented performance of 21.23% is achieved, which is the highest PCE of flexible device based on 2D/3D composite perovskite films coupled with the best mechanical stability due to the 2D/3D alternating structure.     

Perovskite Solar Cells with ZnO Electron‐Transporting Materials

Perovskite solar cells (PSCs) have developed rapidly over the past few years, and the power conversion efficiency of PSCs has exceeded 20%. Such high performance can be attributed to the unique properties of perovskite materials, such as high absorption over the visible range and long diffusion length. Due to the different diffusion lengths of holes and electrons, electron transporting materials (ETMs) used in PSCs play a critical role in PSCs performance. As an alternative to TiO₂ ETM, ZnO materials have similar physical properties to TiO₂ but with much higher electron mobility. In addition, there are many simple and facile methods to fabricate ZnO nanomaterials with low cost and energy consumption. This review focuses on recent developments in the use of ZnO ETM for PSCs. The fabrication methods of ZnO materials are briefly introduced. The influence of different ZnO ETMs on performance of PSCs is then reviewed. The limitations of ZnO ETM‐based PSCs and some solutions to these challenges are also discussed. The review provides a systematic and comprehensive understanding of the influence of different ZnO ETMs on PSCs performance and potentially motivates further development of PSCs by extending the knowledge of ZnO‐based PSCs to TiO₂‐based PSCs.     

Perovskite Solar Cells: From Materials to Devices

Perovskite solar cells based on organometal halide light absorbers have been considered a promising photovoltaic technology due to their superb power conversion efficiency (PCE) along with very low material costs. Since the first report on a long‐term durable solid‐state perovskite solar cell with a PCE of 9.7% in 2012, a PCE as high as 19.3% was demonstrated in 2014, and a certified PCE of 17.9% was shown in 2014. Such a high photovoltaic performance is attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths. Nevertheless, there are lots of puzzles to unravel the basis for such high photovoltaic performances. The working principle of perovskite solar cells has not been well established by far, which is the most important thing for understanding perovksite solar cells. In this review, basic fundamentals of perovskite materials including opto‐electronic and dielectric properties are described to give a better understanding and insight into high‐performing perovskite solar cells. In addition, various fabrication techniques and device structures are described toward the further improvement of perovskite solar cells.