新型钙钛矿太阳能电池的研究进展

太阳能光伏发电是解决目前日益严重的能源与环境问题的一种有效手段,在最近几年里,新型钙钛矿太阳能电池得到迅猛发展,其最高光电转换效率已经达到20%,已成为可再生能源领域的研究热点之一。钙钛矿太阳能电池是以具有钙钛矿结构的有机-金属卤化物等作为核心光吸收、光电转换、光生载流子输运材料的太阳能电池,具有能量转换高和成本低的优点且其核心光电转换材料具有廉价、容易制备的特点,因此获得了学术界的特别关注。首先总结了钙钛矿太阳能电池的结构与原理,然后综述了钙钛矿太阳电池在结构和材料方面的最新研究进展,特别是无铅钙钛矿太阳能电池的一些研究,最后分析了钙钛矿太阳能电池的发展趋势及发展中亟需解决的问题。     

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。     

全钙钛矿叠层太阳能电池的发展与展望（英文）

目前,进一步提高太阳能电池的光电转换效率,降低其度电成本,是实现“双碳”目标的必行之路.全钙钛矿叠层太阳能电池兼备光电转换效率高和成本低廉的优势,近几年取得了巨大的发展,在国际上备受关注,是一种新兴的光伏技术.在展现出巨大潜力的同时,全钙钛矿叠层太阳能电池也面临着多方面的挑战.本文综述了近年来全钙钛矿叠层太阳能电池在宽带隙子电池、窄带隙子电池和隧穿结方面的研究进展,展望了全钙钛矿叠层太阳能电池在效率提升、稳定性改善以及大面积制备等方面的未来发展方向.     

铅卤钙钛矿太阳能电池界面工程的近期进展

铅卤钙钛矿太阳能电池因其优良的光电转换效率以及相对低廉的制备成本而受到广泛关注。然而铅卤钙钛矿太阳能电池的长期稳定性限制了其商业化的进程。界面非辐射复合导致铅卤钙钛矿太阳能电池产生能量损失、影响器件稳定性,是造成器件性能恶化的主要原因。界面工程作为一种有效的策略被用于抑制界面非辐射复合,在制备高效稳定的铅卤钙钛矿太阳能电池方面取得了切实的成效。本文阐述了铅卤钙钛矿太阳能电池的工作原理以及界面上的非辐射复合过程,分析了界面非辐射复合产生的原因,总结了近期n-i-p正式结构铅卤钙钛矿太阳能电池中界面工程的研究进展,讨论了其作用机制。基于目前铅卤钙钛矿太阳能电池中的界面工程发展现状,对其未来的发展方向进行了展望。     

空穴传输材料在高效钙钛矿太阳能电池中的发展演变

钙钛矿太阳能电池(PSCs)转换效率已从2009年的3.8%上升到2017年的22.7%,其快速的发展可能使光伏工业进入革命新阶段。空穴传输材料(HTM)是构成高效钙钛矿太阳能电池的重要组成部分,开发和设计导电性好、成本低、稳定性好的空穴传输层材料对钙钛矿太阳能电池的研究显得非常重要。本文将近几年应用于钙钛矿太阳能电池中较高效的空穴传输材料归纳为有机小分子类、有机聚合物类和无机材料类,同时也介绍了无空穴传输层的钙钛矿电池。详细评述了基于各类空穴传输材料的钙钛矿太阳能电池的光电性能及稳定性,重点讨论了HOMO能级、空穴迁移率、添加剂的掺杂等因素对钙钛矿太阳能电池的影响。最后指出了空穴传输材料未来的研究重点和发展趋势。     

青岛能源所在高质量大面积钙钛矿薄膜制备方面获进展

正中国科学院青岛生物能源与过程研究所青岛储能产业技术研究院研究员逄淑平课题组在钙钛矿大规模制备工艺开发方面取得了突破性进展。有机-无机钙钛矿太阳能电池的光-电转换效率达到22.1%,已超过非晶硅太阳能电池,电池的稳定性不断改善,但钙钛矿太阳能电池从单电池走向组件的核心瓶颈问题是如何制备高质量大面积的钙钛矿薄膜。     

青岛能源所在高质量大面积钙钛矿薄膜制备方面获进展

正中国科学院青岛生物能源与过程研究所青岛储能产业技术研究院研究员逄淑平课题组在钙钛矿大规模制备工艺开发方面取得了突破性进展。有机-无机钙钛矿太阳能电池的光-电转换效率达到22.1%,已超过非晶硅太阳能电池,电池的稳定性不断改善,但钙钛矿太阳能电池从单电池走向组件的核心瓶颈问题是如何制备高质量大面积的钙钛矿薄膜。     

柔性钙钛矿太阳能电池研究进展

近年来,柔性钙钛矿太阳能电池由于具有质量轻、成本低、形状可塑、适用性广等优点,成为了太阳能电池领域炙手可热的研究课题。目前,该类柔性电池的最高光电转换效率已超过16%。本文针对柔性钙钛矿太阳能电池的结构及其柔性衬底,介绍了其主要的研究方向和目前的研究进展,并探讨了柔性钙钛矿太阳能领域面临的主要问题与挑战,最后展望了柔性钙钛矿太阳能电池的发展。     

一步溶液法制备有机金属卤化物钙钛矿薄膜的研究进展

有机金属卤化物钙钛矿太阳能电池兼具很高的光电转换能力和低成本制备优势,俨然已成为最具发展潜力的一类光伏技术。目前,伴随着钙钛矿薄膜质量的不断提升,该技术的最高光电转换效率已经超过22%。一步溶液法制备技术操作简单、商业应用前景广阔,在简要介绍钙钛矿薄膜的制备工艺基础上,重点分析了一步溶液制备法中提高薄膜质量的4种方法,并综述了相关研究进展;最后针对现有钙钛矿太阳能电池存在的问题提出发展展望。     

钙钛矿太阳能电池技术发展历史与现状

简要回顾了钙钛矿太阳能电池的发展历史,解释了钙钛矿太阳能电池本质上是固态染料敏化太阳能电池。介绍了钙钛矿太阳能电池的微观发电机理,结合钙钛矿太阳能电池的能级图分析讨论了钙钛矿与电子传输层和空穴传输层的能级匹配。分析总结了钙钛矿太阳能电池的光伏技术参数,包括光生电流密度、开路电压、填充因子、能量转换效率以及光伏性能的稳定性。钙钛矿太阳能电池的能量转换效率、短路电流密度和开路电压均已超过非晶硅薄膜太阳能电池,填充因子与非晶硅薄膜太阳能电池很接近。钙钛矿太阳能电池有希望实现产业化而成为下一代薄膜太阳能电池。指出了钙钛矿太阳能电池大规模市场应用在制造技术上的瓶颈即空穴传输层的造价昂贵,并综述了解决该瓶颈的最新研究工作。     

Intermolecular π–π Conjugation Self-Assembly to Stabilize Surface Passivation of Highly Efficient Perovskite Solar Cells

Surface passivation is an effective approach to eliminate defects and thus to achieve efficient perovskite solar cells, while the stability of the passivation effect is a new concern for device stability engineering. Herein, tribenzylphosphine oxide (TBPO) is introduced to stably passivate the perovskite surface. A high efficiency exceeding 22%, with steady-state efficiency of 21.6%, is achieved, which is among the highest performances for TiO₂ planar cells, and the hysteresis is significantly suppressed. Further density functional theory (DFT) calculation reveals that the surface molecule superstructure induced by TBPO intermolecular π–π conjugation, such as the periodic interconnected structure, results in a high stability of TBPO–perovskite coordination and passivation. The passivated cell exhibits significantly improved stability, with sustaining 92% of initial efficiency after 250 h maximum-power-point tracking. Therefore, the construction of a stabilized surface passivation in this work represents great progress in the stability engineering of perovskite solar cells.     

Interface and Defect Engineering for Metal Halide Perovskite Optoelectronic Devices

Metal halide perovskites have been in the limelight in recent years due to their enormous potential for use in optoelectronic devices, owing to their unique combination of properties, such as high absorption coefficient, long charge‐carrier diffusion lengths, and high defect tolerance. Perovskite‐based solar cells and light‐emitting diodes (LEDs) have achieved remarkable breakthroughs in a comparatively short amount of time. As of writing, a certified power conversion efficiency of 22.7% and an external quantum efficiency of over 10% have been achieved for perovskite solar cells and LEDs, respectively. Interfaces and defects have a critical influence on the properties and operational stability of metal halide perovskite optoelectronic devices. Therefore, interface and defect engineering are crucial to control the behavior of the charge carriers and to grow high quality, defect‐free perovskite crystals. Herein, a comprehensive review of various strategies that attempt to modify the interfacial characteristics, control the crystal growth, and understand the defect physics in metal halide perovskites, for both solar cell and LED applications, is presented. Lastly, based on the latest advances and breakthroughs, perspectives and possible directions forward in a bid to transcend what has already been achieved in this vast field of metal halide perovskite optoelectronic devices are discussed.     

Stable and High-Efficiency Methylammonium-Free Perovskite Solar Cells

Organic–inorganic metal halide perovskite solar cells (PSCs) have achieved certified power conversion efficiency (PCE) of 25.2% with complex compositional and bandgap engineering. However, the thermal instability of methylammonium (MA) cation can cause the degradation of the perovskite film, remaining a risk for the long-term stability of the devices. Herein, a unique method is demonstrated to fabricate highly phase-stable perovskite film without MA by introducing cesium chloride (CsCl) in the double cation (Cs, formamidinium) perovskite precursor. Moreover, due to the suboptimal bandgap of bromide (Br⁻), the amount of Br⁻ is regulated, leading to high power conversion efficiency. As a result, MA-free perovskite solar cells achieve remarkable long-term stability and a PCE of 20.50%, which is one of the best results for MA-free PSCs. Moreover, the unencapsulated device retains about 80% of the original efficiencies after a 1000 h aging study. These results provide a feasible approach to enhance solar cell stability and performance simultaneously, paving the way for commercializing PSCs.     

Compositional Engineering for Thermally Stable,Highly Efficient Perovskite Solar Cells Exceeding 20% Power Conversion Efficiency with 85 °C/85% 1000 h Stability

Perovskite solar cells have received great attention because of their rapid progress in efficiency, with a present certified highest efficiency of 23.3%. Achieving both high efficiency and high thermal stability is one of the biggest challenges currently limiting perovskite solar cells because devices displaying stability at high temperature frequently suffer from a marked decrease of efficiency. In this report, the relationship between perovskite composition and device thermal stability is examined. It is revealed that Rb can suppress the growth of PbI₂ even under PbI₂‐rich conditions and decreasing the Br ratio in the perovskite absorber layer can prevent the generation of unwanted RbBr‐based aggregations. The optimized device achieved by engineering perovskite composition exhibits 92% power conversion efficiency retention in a stress test conducted at 85 °C/85% relative humidity (RH) according to an international standard (IEC 61215) while exceeding 20% power conversion efficiency (certified efficiency of 20.8% at 1 cm²). These results reveal the great potential for the practical use of perovskite solar cells in the near future.     

湿度对钙钛矿太阳能电池性能及其稳定性的影响

本文在不同湿度的空气中采用两步旋涂法制备钙钛矿太阳能电池并对电池进行稳定性测试,系统地研究了湿度对电池性能及其稳定性的影响。研究结果表明:随着制备环境湿度的增大,PbI_2薄膜与钙钛矿薄膜覆盖率下降,导致电池吸光性能和光电转换效率的降低;将电池置于不同湿度的空气中30天后,湿度越大,电池效率下降越快,且电池稳定性的降低主要是由于钙钛矿发生了分解。     

Organic–Inorganic Hybrid Perovskite with Controlled Dopant Modification and Application in Photovoltaic Device

Organic–inorganic hybrid perovskite as a kind of promising photovoltaic material is booming due to its low‐cost, high defect tolerance, and easy fabrication, which result in the huge potential in industrial production. In the pursuit of high efficiency photovoltaic devices, high‐quality absorbing layer is essential. Therefore, developing organic–inorganic hybrid perovskite thin films with good coverage, improved uniformity, and crystalline in a single pass deposition is of great concern in realizing good performance of perovskite thin‐film solar cell. Here, it is found that the introduction of suitable amounts of LiI plays a dramatically positive role in enlarging the grain size and reducing the grain boundaries of absorbing layer. In addition, the carrier lifetime and built‐in potential of the LiI doped perovskite device are observed to increase. Thus, it leads to about 15% gain in solar cell efficiency comparing to that without the LiI doping. Meanwhile, a hysteresis reduction is observed and 18.16% power conversion efficiency is achieved in LiI doped perovskite device, as well.     

高分子PVP添加剂对钙钛矿太阳电池稳定性的提升

作为一类新型薄膜太阳能电池, 近年来钙钛矿太阳电池的发展十分迅速, 其效率已接近商业化硅基太阳能电池, 但是钙钛矿薄膜在空气中稳定性较差, 严重限制了其进一步的商业化应用。本研究通过在钙钛矿薄膜中添加聚4-乙烯吡啶(PVP)来增强钙钛矿薄膜在空气中的稳定性。通过形貌、结构及性能测试, 发现相比于未添加PVP的钙钛矿薄膜, 添加PVP的钙钛矿薄膜形貌更均匀致密。添加0.4wt% PVP将钙钛矿太阳电池的光电效率从6.09%提升到13.07%, 而且, 存放在相对湿度超过50%的空气中, 其电池效率衰减为一半的时间由原来的3 d延长到3 w, 但是过多的PVP添加量会导致PbI₂与CH₃NH₃I反应不完全。添加PVP工艺进一步优化后, 有望用于大面积、高稳定性的钙钛矿薄膜的制备。     

Metal halide perovskite: a game-changer for photovoltaics and solar devices via a tandem design

Multi-junction tandem design has been proven to be an effective means to further improve the efficiency of solar cells. However, its share in the photovoltaics market at present is tiny, since the most efficient tandem device comprises III-V semiconductors, which entail the use of expensive fabrication processes. The advent of perovskite solar cells, which have revitalized the PV field with their unprecedented pace of development, promises to address this bottleneck. Perovskite materials could not only serve as the top subcell absorber for commercial solar cells including Si and copper indium gallium selenide, but could work efficiently as bottom subcells owing to highly tuneable bandgaps which extend down to the range of ~1.2 to 1.5 eV. The highest-efficiency perovskite tandem to date was achieved by pairing a perovskite top cell with a Si bottom cell in a four-terminal configuration, yielding 26.4%. This review gives an overview of recent progress on the main tandem structures, and describes the detailed design improvements that have resulted in new record efficiencies. Ultimately, commercialization of these tandem solar cells relies on the scalability of perovskite technology. We, therefore, highlight the development of large-scale tandems and approaches to produce perovskite modules. We also point out the critical aspects that will require further effort and provide guidelines for future developments. The potential obstacles that will hamper the commercialization of perovskite tandems, if not adequately addressed, namely device stability and toxicity, are then critically examined. Finally, the substantial opportunities that perovskite materials open up for other solar devices with a tandem configuration are mentioned, which are attracting increasing attention.     

Methodologies toward Highly Efficient Perovskite Solar Cells

A perovskite solar cell (PSC) employing an organic–inorganic lead halide perovskite light harvester, seeded in 2009 with power conversion efficiency (PCE) of 3.8% and grown in 2011 with PCE of 6.5% in dye‐sensitized solar cell structure, has received great attention since the breakthrough reports ≈10% efficient solid‐state PCSs demonstrating 500 h stability. Developments of device layout and high‐quality perovskite film eventually lead to a PCE over 22%. As of October 31, 2017, the highest PCE of 22.7% is listed in an efficiency chart provided by NREL. In this Review, the methodologies to obtain highly efficient PSCs are described in detail. In order to achieve a PCE of over 20% reproducibly, key technologies are disclosed from the viewpoint of precursor solution chemistry, processing for defect‐free perovskite films, and passivation of grain boundaries. Understanding chemical species in precursor solution, crystal growth kinetics, light–matter interaction, and controlling defects is expected to give important insights into not only reproducible production of high PCE over 20% but also further enhancement of the PCE of PCSs.