复合钙钛矿太阳能电池电荷传输层材料研究进展

有机无机复合钙钛矿太阳能电池因具有适合的载流子扩散长度而成为备受关注的有望获得高效率的光伏器件。复合钙钛矿材料本身不含贵金属元素,可以采用液相法或物理气相法低温制备,成本低廉,但目前应用最多的电子传输层材料TiO2需400~500℃煅烧,与柔性基底及低温制备技术适应性差;空穴传输层材料SpiroOMeTAD合成工艺复杂,价格高昂,限制了复合钙钛矿太阳能电池的开发应用。开发和研究导电性好、成本低、稳定性好的电子和空穴传输层材料是复合钙钛矿太阳能电池研究中的一个非常重要的方面。综述了复合钙钛矿太阳能电池中电荷传输层材料的研究进展及发展方向。电子传输层材料方面通过对TiO2的改性以及与石墨烯的复合,采用ZnO、石墨烯或PCBM作为电子传输层材料,以与柔性基底及低温制备技术相适应。空穴传输层材料方面,采用其它低成本、导电性高的有机p型半导体替代spiro-OMeTAD;采用无机空穴传输层材料以避免有机空穴传输层材料的老化问题,提高电池的长期稳定性;利用复合钙钛矿材料兼作吸收层与空穴传输层,制备无空穴传输层材料结构电池以降低成本,提高稳定性。     

钙钛矿太阳能电池的研究进展

作为一种新型清洁可再生能源,钙钛矿太阳能电池(Perovskite solar cells,PSC)从发展至今已取得了重大的突破,成为研究的热点。主要介绍了钙钛矿太阳能电池的基本结构和工作原理及电子传输层、钙钛矿层、空穴传输层的制备方法,以及在发展过程中所面临的技术问题,最后展望了钙钛矿太阳能电池未来的研究重点及发展前景。     

有机电子传输材料在反式钙钛矿太阳能电池中的研究现状

近年来,反式结构的钙钛矿太阳能电池凭借制备工艺简单、可低温成膜、迟滞效应低、适合与传统太阳能电池结合制备叠层器件等优点,受到了人们广泛的关注,经过几年的发展,反式钙钛矿太阳能电池的光电转化效率已从3.9%提升到25.37%。其中电子传输层作为钙钛矿太阳能电池的重要组成部分,在提取和运输载流子、阻挡空穴、调节界面能级结构和抑制电荷复合等方面起着关键性的作用。一些有机材料(富勒烯及其衍生物、苝二酰亚胺、萘二酰亚胺等)凭借容易合成和纯化、能级可调、电子迁移率高、溶解性好、化学/热稳定性良好等优势,已经广泛应用于反式钙钛矿太阳能电池。本文主要介绍了不同有机电子传输材料在反式钙钛矿太阳能电池中的研究现状,还介绍了电子传输层掺杂和界面修饰两种提升器件性能的改性手段,旨在为开发全新的有机电子传输材料提供基础性的理论指导。     

钙钛矿太阳能电池空穴传输材料的研究进展

钙钛矿太阳能电池具有工艺简单、可弯曲、应用前景广阔等优点。从2009年出现起,至今其效率从3.8%提高到了22%以上,引起了研究者的广泛关注。介绍了钙钛矿太阳能电池的基本结构和工作原理,概述了钙钛矿太阳能电池空穴传输材料的研究进展,着重介绍了无机空穴传输材料的研究进展。最后展望了钙钛矿太阳能电池未来的发展与商业化应用。     

倒置钙钛矿太阳能电池的空穴传输层的研究进展

倒置钙钛矿太阳能电池(PSCs)具有器件结构简单、吸光系数高、迟滞效应小、良好的缺陷容忍性等优点,受到了广泛的关注。但倒置器件光电转换效率(PCE)尚有待提高,究其原因是空穴传输层(HTL)和钙钛矿层界面处的能量损失表现出相对较小的开路电压。文章综述了包括有机聚合物、无机物、尖晶石氧化物等作为空穴传输材料的相关研究进展,进一步分析了通过调节电极/空穴传输层能级使之与钙钛矿价带匹配,及通过界面修饰促进器件对载流子的注入与收集,从而提高光电转换效率的研究现状。对提高倒置钙钛矿太阳能电池性能的研究具有一定的指导意义,最后对倒置器件的应用前景进行了展望。     

钙钛矿太阳能电池界面工程优化研究

有机-无机杂化钙钛矿太阳能电池(PSCs)具有高能量转换效率、低能耗和低成本等优点,但PSCs界面缺陷引起的非辐射复合严重阻碍了其光电转换性能提升。本研究通过降低氧化镍空穴传输层的粒径尺寸,提高粒径均匀性,实现了光生空穴在电池界面的高效传输;并通过优化钙钛矿薄膜的反溶剂作用时间提升结晶质量,降低界面非辐射复合,改善空穴传输层和钙钛矿的界面问题,使钙钛矿太阳能电池的能量转换效率(PCE)从10.11%提高到18.37%。开尔文探针力显微镜(KPFM)研究表明,界面优化后的钙钛矿薄膜在亮态下的表面接触电位差相比于暗态下增加了120.39 mV。采用压电力原子力显微镜(PFM)分析钙钛矿薄膜明暗态铁电性能,发现界面优化后的钙钛矿铁电极化变化微弱,说明优化界面有效降低了电池界面缺陷和迟滞效应。该研究结果表明,优化氧化镍空穴传输层,提高钙钛矿薄膜质量,减少了界面缺陷,降低了非辐射复合和电池迟滞效应,提高了钙钛矿太阳能电池的能量转换效率。     

钙钛矿太阳能电池中NiOx空穴传输层的研究进展

半导体氧化镍（NiO_x）价格便宜、空穴迁移率高、化学稳定性好且可低温制备,由其作为空穴传输层（HTL）制备的反式钙钛矿太阳能电池极具市场应用前景。NiO_x HTL的制备与优化对电池器件的性能至关重要。系统介绍了钙钛矿太阳能电池中NiO_x薄膜的制备工艺及其研究进展。阐述了O₂-plasma、紫外、表面钝化等后处理方式对NiO_x薄膜的缺陷态、表面化学状态以及材料功函数的调控影响。重点综述了掺杂（过渡金属、碱金属、稀土元素掺杂和元素共掺杂）对NiO_x薄膜光学和电学性能以及器件光电性能的影响。最后对NiO_x基钙钛矿太阳能电池的未来发展方向进行了展望。     

基于能带工程制备氧化镍基底的高效锡-铅共混钙钛矿太阳能电池

钙钛矿叠层太阳能电池因为具有超过肖克利-奎伊瑟效率极限的潜力而备受关注.窄带隙锡-铅(Sn-Pb)共混钙钛矿太阳能电池(PSCs)在钙钛矿叠层太阳能电池的构建中起着关键作用.制备稳定性好、可低温处理的空穴输送层是构建高效Sn-Pb钙钛矿太阳能电池和钙钛矿叠层太阳能电池的关键.在此,我们开发了一种室温处理的纳米晶体氧化镍...     

以ZnO纳米棒阵列为电子传输层的无空穴层有机-无机杂化钙钛矿太阳能电池

近年来,有机-无机杂化钙钛矿太阳能电池(PSCs)发展迅速,其光电转化效率(PCE)已提升至23.3%,成为当今太阳能电池领域无可争议的研究焦点。研究发现,PSCs结构组成与性质对光电性能影响显著。其中,电子传输层的形貌结构不仅影响钙钛矿晶体的成长,同时也决定了电子扩散系数和电子寿命。本工作将ZnO纳米棒阵列(Nanorods array,NRAs)作为电子传输层,应用于无空穴传输层的基于碳对电极的杂化钙钛矿太阳能电池中。通过水热法制备了不同长度的ZnO NRAs,经测试发现,对应的钙钛矿电池的PCE随ZnO NRAs长度的增加呈先升高后下降的趋势,当ZnO NRAs长度为454 nm时,PCE最优为6.18%。     

基于有机金属卤化物钙钛矿材料的全固态太阳能电池研究进展

作为太阳能电池的光吸收剂,有机金属卤化物钙钛矿材料不仅具有高效的光吸收能力和载流子迁移率,还具有独特的双极性特征,能同时传输电子和空穴,使其成为优异的光伏材料,掀起了基于钙钛矿材料太阳能电池的研究热潮。介绍了近几年来基于有机金属卤化物钙钛矿材料的全固态太阳能电池的发展情况,总结了有机金属卤化物钙钛矿材料的结构和特性,对目前几类典型的钙钛矿太阳能电池进行了讨论,并展望了全固态钙钛矿太阳能电池的产业化应用前景。     

Intensive Exposure of Functional Rings of a Polymeric Hole‐Transporting Material Enables Efficient Perovskite Solar Cells

A variety of dopant‐free hole‐transporting materials (HTMs) is effectively applied in perovskite solar cells (PSCs); however, HTMs with the additional function of HTM/perovskite interfacial optimization that is crucial to their photovoltaic performance are really limited. In this work, the design of an HTM bearing an intensive exposure of its functional aromatic rings to perovskite layer via side‐chain engineering is attempted. With an edge‐on orientation and a short distance to perovskite, this HTM was expected to display an excellent ability to extract holes from and passivate defects in the perovskite layer. To demonstrate this strategy, an alternating copolymer was constructed with a 2,5‐di‐2‐ethylhexyloxy‐1,4‐phenylene unit and a bithiophene unit, and the PSC based on this polymer showed an ultrahigh short‐circuit current density of 25.50 mA cm^?2, which was the highest so far presented by dopant‐free organic HTMs. A comparable power conversion efficiency of 19.68% (certified: 19.5%) to that of a control 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) device (19.81%) was thus obtained, which is the highest value ever reported for mesoporous PSCs based on dopant‐free polymeric HTMs.     

Recent progress in efficient hybrid lead halide perovskite solar cells

The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices.     

Recent progress in efficient hybrid lead halide perovskite solar cells

Abstract

The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices.     

Emerging Semitransparent Solar Cells: Materials and Device Design

Semitransparent solar cells can provide not only efficient power‐generation but also appealing images and show promising applications in building integrated photovoltaics, wearable electronics, photovoltaic vehicles and so forth in the future. Such devices have been successfully realized by incorporating transparent electrodes in new generation low‐cost solar cells, including organic solar cells (OSCs), dye‐sensitized solar cells (DSCs) and organometal halide perovskite solar cells (PSCs). In this review, the advances in the preparation of semitransparent OSCs, DSCs, and PSCs are summarized, focusing on the top transparent electrode materials and device designs, which are all crucial to the performance of these devices. Techniques for optimizing the efficiency, color and transparency of the devices are addressed in detail. Finally, a summary of the research field and an outlook into the future development in this area are provided.     

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.     

Enhancing Crystallization in Hybrid Perovskite Solar Cells Using Thermally Conductive 2D Boron Nitride Nanosheet Additive

Controlling crystallization and grain growth is crucial for realizing highly efficient hybrid perovskite solar cells (PSCs). In this work, enhanced PSC photovoltaic performance and stability by accelerating perovskite crystallization and grain growth via 2D hexagonal boron nitride (hBN) nanosheet additives incorporated into the active perovskite layer are demonstrated. In situ X-ray scattering and infrared thermal imaging during the perovskite annealing process revealed the highly thermally conductive hBN nanosheets promoted the phase conversion and grain growth in the perovskite layer by facilitating a more rapid and spatially uniform temperature rise within the perovskite film. Complementary structural, physicochemical, and electrical characterizations further showed that the hBN nanosheets formed a physical barrier at the perovskite grain boundaries and the interfaces with charge transport layers, passivating defects, and retarding ion migration. As a result, the power conversion efficiency of the PSC is improved from 17.4% to 19.8%, along with enhanced device stability, retaining ≈90% of the initial efficiency even after 500 h ambient air storage. The results not only highlight 2D hBN as an effective additive for PSCs but also suggest enhanced thermal transport as one of the pathways for improved PSC performance by 2D material additives in general.     

稀土上转换发光在钙钛矿太阳能电池中的应用

目前,钙钛矿太阳能电池最常使用的钙钛矿材料为CH_3NH_3PbI_3,其禁带宽度为1.55eV,导致低于该能量值的太阳光的光子无法被直接地吸收利用。因此,提高器件对太阳光谱的响应范围是提高钙钛矿太阳能电池性能的关键。稀土上转换材料可以将低能量近红外光转换为高能量可见光,所以,稀土上转换发光的应用是提高钙钛矿太阳能电池性能的较为可行的途径。本文概述了稀土上转换发光的基本机制,介绍了钙钛矿太阳能电池的结构和工作原理,综述了该太阳能电池的研究现状及其主要优势,重点阐述了稀土上转换发光在钙钛矿太阳能电池中的应用,最后对该太阳能电池的发展前景进行了展望。     

2D Perovskites with Short Interlayer Distance for High‐Performance Solar Cell Application

2D perovskites have emerged as one of the most promising photovoltaic materials owing to their excellent stability compared with their 3D counterparts. However, in typical 2D perovskites, the highly conductive inorganic layers are isolated by large organic cations leading to quantum confinement and thus inferior electrical conductivity across layers. To address this issue, the large organic cations are replaced with small propane‐1,3‐diammonium (PDA) cations to reduce distance between the inorganic perovskite layers. As shown by optical characterizations, quantum confinement is no longer dominating in the PDA‐based 2D perovskites. This leads to considerable enhancement of charge transport as confirmed with electrochemical impedance spectroscopy, time‐resolved photoluminescence, and mobility measurements. The improved electric properties of the interlayer‐engineered 2D perovskites yield a power conversion efficiency of 13.0%. Furthermore, environmental stabilities of the PDA‐based 2D perovskites are improved. PDA‐based 2D perovskite solar cells (PSCs) with encapsulation can retain over 90% of their efficiency upon storage for over 1000 h, and PSCs without encapsulation can maintain their initial efficiency at 70 °C for over 100 h, which exhibit promising stabilities. These results reveal excellent optoelectronic properties and intrinsic stabilities of the layered perovskites with reduced interlayer distance.     

Low‐Cost and Highly Efficient Carbon‐Based Perovskite Solar Cells Exhibiting Excellent Long‐Term Operational and UV Stability

Today's perovskite solar cells (PSCs) mostly use components, such as organic hole conductors or noble metal back contacts, that are very expensive or cause degradation of their photovoltaic performance. For future large‐scale deployment of PSCs, these components need to be replaced with cost‐effective and robust ones that maintain high efficiency while ascertaining long‐term operational stability. Here, a simple and low‐cost PSC architecture employing dopant‐free TiO₂ and CuSCN as the electron and hole conductor, respectively, is introduced while a graphitic carbon layer deposited at room temperature serves as the back electrical contact. The resulting PSCs show efficiencies exceeding 18% under standard AM 1.5 solar illumination and retain ≈95% of their initial efficiencies for >2000 h at the maximum power point under full‐sun illumination at 60 °C. In addition, the CuSCN/carbon‐based PSCs exhibit remarkable stability under ultraviolet irradiance for >1000 h while under similar conditions, the standard spiro‐MeOTAD/Au based devices degrade severely.     

Thermally Stable MAPbI3 Perovskite Solar Cells with Efficiency of 19.19% and Area over 1 cm2 achieved by Additive Engineering

Solution‐processed perovskite (PSC) solar cells have achieved extremely high power conversion efficiencies (PCEs) over 20%, but practical application of this photovoltaic technology requires further advancements on both long‐term stability and large‐area device demonstration. Here, an additive‐engineering strategy is developed to realize a facile and convenient fabrication method of large‐area uniform perovskite films composed of large crystal size and low density of defects. The high crystalline quality of the perovskite is found to simultaneously enhance the PCE and the durability of PSCs. By using the simple and widely used methylammonium lead iodide (MAPbI₃), a certified PCE of 19.19% is achieved for devices with an aperture area of 1.025 cm², and the high‐performing devices can sustain over 80% of the initial PCE after 500 h of thermal aging at 85 °C, which are among the best results of MAPbI₃‐based PSCs so far.