钙钛矿光伏电池封装材料与工艺研究进展

钙钛矿太阳能电池作为第3代新概念太阳能电池,具有高光电转换效率、低成本和可柔性加工等优点,近年来发展迅速,其光电转换效率从一开始的3.8%增长到近期的25.5%,逐渐比肩硅电池,已接近商业化应用水平。目前,实现钙钛矿太阳能电池产业应用的关键环节在于电池封装,它不仅可以解决钙钛矿光伏器件稳定性问题,还可以实现电池安全、环保和延长使用寿命等要求。结合近十几年来钙钛矿光伏电池封装材料和封装工艺两方面的发展现状,文中介绍了钙钛矿电池封装领域取得的成果和存在的不足,讨论了目前现有封装技术的优缺点,以及它们适用的不同器件类型。着重在不同温度湿度条件下,比较了不同封装材料性能、封装工艺条件对钙钛矿电池效率及稳定性的影响,归纳出影响钙钛矿电池薄膜封装效果的3个关键因素： 聚合物的弹性模量、水蒸气透过率、加工温度。比较了不同聚合物薄膜封装材料适宜的加工温度、优缺点及加工成本。可以看出,随着钙钛矿光伏电池工业化需求的强烈增长和人们对其封装材料研究的不断深入,研究适合大面积生产和光伏建筑一体化的新型功能聚合物封装材料将是必然趋势。     

无机非铅钙钛矿太阳能电池研究进展

钙钛矿太阳能电池因其光吸收效率高、载流子寿命长、晶格缺陷容忍度高、能带可调等优点得到迅速发展,在短短几年内其太阳能转化效率已经达到22.1%。然而,在人们看到钙钛矿太阳能电池广阔发展前景的同时,其铅毒性和不稳定性严重限制了它的应用推广。无机非铅钙钛矿太阳能电池(ABX_3、A_2BB′X_6等)利用Sn、Ge、Bi、Ag等金属取代铅,以Cs、Rb等取代甲胺有希望解决目前钙钛矿太阳能电池的毒性和稳定性问题。本文主要对近几年无机非铅钙钛矿太阳能电池的研究现状做一个分析总结,并对其发展前景进行展望。     

New advances in small molecule hole-transporting materials for perovskite solar cells

Organic π-functional molecules are the foundation and basic component of organic optoelectronic devices.For example,for ideal carrier transporting materials,extended π-conjugation and ordered π-πstacking are necessary to enhance the charge mobility and achieve desirable results.As a promising way to convert sunlight into electricity,organometal halide perovskite solar cells(PSCs) have captured a lot of attention due to its predominant merits especially in the aspect of remarkable photovoltaic performance and much potentially low production cost.For conventional planar PSC structure,hole-transporting layer which typically consists of organic π-functional materials plays a key role in suppressing holeelectron pair recombination,promoting charge transporting and ensuring ohmic contact of back electrode.Considering the key roles of HTMs and its soaring progress in recent years,here,we will summarize recent progress in small organic π-functional materials from its diverse functions in PSCs.Besides,aiming to further promote the development of organic π-functional molecules and HTMs,a promising direction toward highly efficient HTMs will also be discussed.     

钙钛矿太阳电池吸光层材料研究进展

近年来,有机-无机卤化铅钙钛矿太阳电池的研究取得了突破性进展,公证记录电池效率22.1%,与CdTe薄膜电池（认证记录电池效率22.1%）和CuInGaSn（CIGS）（认证记录电池效率22.3%）薄膜电池技术相媲美,已经接近于市场上主导地位的晶体硅太阳电池（约25%）。有机卤化铅钙钛矿太阳电池器件的长期效率输出稳定性和含毒性Pb严重制约其实际应用。本文将讨论有机卤化铅钙钛矿太阳电池不稳定性因素和相应的解决方案,并对钙钛矿材料中Pb元素的取代工作和无机非铅钙钛矿材料及其太阳电池的研究进行了阐述与展望。     

Iodonium Initiators: Paving the Air-free Oxidation of Spiro-OMeTAD for Efficient and Stable Perovskite Solar Cells

To date, perovskite solar cells (pero-SCs) with doped 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) hole transporting layers (HTLs) have shown the highest recorded power conversion efficiencies (PCEs). However, their commercialization is still impeded by poor device stability owing to the hygroscopic lithium bis(trifluoromethanesulfonyl)imide and volatile 4-tert-butylpyridine dopants as well as time-consuming oxidation in air. In this study, we explored a series of single-component iodonium initiators with strong oxidability and different electron delocalization properties to precisely manipulate the oxidation states of Spiro-OMeTAD without air assistance, and the oxidation mechanism was clearly understood. Iodine (III) in the diphenyliodonium cation (IP⁺) can accept a single electron from Spiro-OMeTAD and forms Spiro-OMeTAD⋅⁺ owing to its strong oxidability. Moreover, because of the coordination of the strongly delocalized TFSI⁻ with Spiro-OMeTAD⋅⁺ in a stable radical complex, the resulting hole mobility was 30 times higher than that of pristine Spiro-OMeTAD. In addition, the IP-TFSI initiator facilitated the growth of a homogeneous and pinhole-free Spiro-OMeTAD film. The pero-SCs based on this oxidizing HTL showed excellent efficiencies of 25.16 % (certified: 24.85 % for 0.062-cm²) and 20.71 % for a 15.03-cm² module as well as remarkable overall stability.     

Perovskite Films Regulation via Hydrogen-Bonded Polymer Network for Efficient and Stable Perovskite Solar Cells

Perovskite solar cells (PSCs) are considered as a promising photovoltaic technology due to their high efficiency and low cost. However, their long-term stability, mechanical durability, and environmental risks are still unable to meet practical needs. To overcome these issues, we designed a multifunctional elastomer with abundant hydrogen bonds and carbonyl groups. The chemical bonding between polymer and perovskite could increase the growth activation energy of perovskite film and promote the preferential growth of high-quality perovskite film. Owing to the low defect density and gradient energy-level alignment, the corresponding device exhibited a champion efficiency of 23.10 %. Furthermore, due to the formation of the hydrogen-bonded polymer network in the perovskite film, the target devices demonstrated excellent air stability and enhanced flexibility for the flexible PSCs. More importantly, the polymer network could coordinate with Pb²⁺ ions, immobilizing lead atoms to reduce their release into the environment. This strategy paves the way for the industrialization of high-performance flexible PSCs.     

A Multifunctional Polymer as an Interfacial Layer for Efficient and Stable Perovskite Solar Cells

Metal-cation defects and halogen-anion defects in perovskite films are critical to the efficiency and stability of perovskite solar cells (PSCs). In this work, a random polymer, poly(methyl methacrylate-co-acrylamide) (PMMA-AM), was synthesized to serve as an interfacial passivation layer for synergistically passivating the under-coordinated Pb²⁺ and anchor the I^- of the [PbI₆]⁴⁻ octahedron. Additionally, the interfacial PMMA-AM passivation layer cannot be destroyed during the hole transport layer deposition because of its low solubility in chlorobenzene. This passivation leads to an enhancement in the open-circuit voltage from 1.12 to 1.22 V and improved stability in solar cell devices, with the device maintaining 95 % of the initial power conversion efficiency (PCE) over 1000 h of maximum power point tracking. Additionally, a large-area solar cell module was fabricated using this approach, achieving a PCE of 20.64 %.     

A review on two-dimensional (2D) and 2D-3D multidimensional perovskite solar cells: Perovskites structures,stability, and photovoltaic performances

Perovskite solar cells (PSCs) fabricated with two-dimensional (2D) halide and 2D-3D mixed-halide materials are remarkable for their optoelectronic properties. The 2D perovskite structures are extremely stable but show limited charge transport and large bandgap for solar cell applications. To overcome these challenges, multidimensional 2D-3D perovskite materials are used to maintain simultaneously, a long-term stability, and high performance. In this review, we discuss the recent progress and the advantages of 2D and 2D-3D perovskite materials as absorber for solar cell applications. First, we discuss the structure and the unique properties of 2D and multidimensional 2D-3D perovskites materials. Second, the stability of 2D and 2D-3D mixed perovskites and the perspects of PSCs are hashed out.     

平板结构高效钙钛矿太阳能电池的旋涂溶液溶剂工程

自2009年首次应用于太阳能电池中以来,有机铅卤化物钙钛矿材料得到了极大关注.据文献报道,有机铅卤化物钙钛矿材料在不同结构的太阳能电池中都得到了应用,其中与有机太阳能电池类似的平板结构钙钛矿具有结构简单、制备容易等优点,非常适合用于柔性电池和多节电池等各种应用.在平板结构的太阳能电池中,制备高质量的钙钛矿薄膜至关重要.真空热蒸镀法虽然可以制备厚度均匀的钙钛矿薄膜,获得高的器件性能,但是设备成本较高,不利于大规模生产.而在溶液法中,早期的一步旋涂法和两步法由于没有多孔金属氧化物的支撑,很难制备均匀的钙钛矿平板薄膜;而气相辅助的两步法虽然制备的薄膜比较均匀,但反应时间却比较长.程一兵研究组采用在旋涂N,N-二甲基甲酰胺(DMF)溶液时滴加氯苯使钙钛矿快速析出结晶的方法,制备了高质量的均匀的CH3NH3PbI3薄膜. Seok研究组采用1,4-丁内酯(GBL)和二甲基亚砜(DMSO)的混和溶剂,在旋涂时滴加甲苯的方法,在多孔二氧化钛上也制得了均匀的CH3NH3PbI3薄膜,取得了很高转化效率(16.7%),但缺少对不同溶剂比例的细致研究,另外,也没有对平板结构电池性能进行研究.
　　本文采用DMF-DMSO和GBL-DMSO作为混合溶剂在二氧化钛致密层上旋涂制备了平板结构的钙钛矿薄膜,并且对混合溶剂的比例对器件性能的影响进行了详细的考察和优化.当纯DMF或纯GBL作为旋涂溶剂时,得到的CH3NH3PbI3钙钛矿薄膜含有大量不连续的晶粒,表面的覆盖度很差,对入射光的吸收远弱于连续均匀的薄膜.而且XRD结果表明,纯DMF或纯GBL作为旋涂溶剂的薄膜残留有前驱体的杂质,对器件性能非常不利.而采用DMSO作为旋涂溶剂时,制得的薄膜表面则比较均匀,几乎达到100%的覆盖.这主要是由于在旋涂溶液中形成了PbI2-CH3NH3I-DMSO的中间相,这样可以避免纯DMF或纯GBL溶剂蒸发时PbI2和CH3NH3I的剧烈反应,因此退火后制得的CH3NH3PbI3薄膜非常均匀.然而由于纯DMSO的高粘度和低挥发速度,并不是非常适合作为旋涂溶剂,因此我们将DMF和GBL加入到DMSO中形成混合溶剂来考察对制备的钙钛矿薄膜质量和器件性能的影响.扫描电镜结果表明,加入20%~40%体积分数的DMF时,形成的薄膜表面非常均匀而且晶粒尺寸很大,达到微米级别,这样有利于减少晶界处的复合,提高电池性能.继续增加DMF比例会导致晶粒减小,晶界和孔隙增多,薄膜表面也更加粗糙.而加入GBL时得到的晶粒要远小于加入DMF时的尺寸,并且随着GBL比例的增加,薄膜的表面变得更加粗糙,孔隙明显增多,严重影响电池性能. XRD结果表明,纯DMSO和混合溶剂制得的薄膜都没有前驱体的残留.紫外可见吸收光谱表明,随着DMF比例的增加,吸收逐渐增强;而随着GBL比例的增加,吸收逐渐减弱.这主要由于不同比例溶剂制得的薄膜厚度有所差异造成的.
　　由相关的薄膜制备的平板结构太阳能电池I-V测试表明：当使用DMF-DMSO混合溶剂时,随着DMF比例由0%增至40%,短路电流和开路电压逐渐增加,填充因子略微减小,总体上导致光电转化效率逐渐增大.随着DMF继续增多,开路电压和填充因子的减小导致转化效率逐渐降低.而当使用GBL-DMSO混合溶剂时,主要受到短路电流的影响,电池的效率明显低于含DMF的混合溶剂的情况,而且随着GBL增多,电池效率逐渐降低.电池的最高转化效率达到了16.5%,最高功率点下固定电压扫描得到的稳态效率也达到了14.4%,高于报道中采用类似结构的电池的性能.由于在整个电池制备过程中,整个实验过程都低于100°C,该方法非常适合未来推广到柔性太阳能电池和多节太阳能电池上.     

Theoretical study on halide and mixed halide Perovskite solar cells: Effects of halide atoms on the stability and electronic properties

Increasing the stability of perovskite solar cells is one of the most important tasks in the photovoltaic industry. Thus, the structural, energetic, and electronic properties of pure CH₃NH₃PbI₃ and fully doped compounds (CH₃NH₃PbBr₃ and CH₃NH₃PbCl₃) in cubic and tetragonal phases were investigated using density functional theory calculations. We also considered the effects of mixed halide perovskites CH₃NH₃PbI₂X (where X = Br and Cl) and compared their properties with CH₃NH₃PbI₃. The DFT results indicate that the phase transformation from tetragonal to cubic phase decreases the band gap. The calculated results show that the X‐site ion plays a vital role in the geometrical stability and electronic levels. An increase in the band gap and a reduction in the lattice constants are more apparent in CH₃NH₃PbI₂X compounds (I > Br > Cl).     

Rapid development in two-dimensional layered perovskite materials and their application in solar cells

This review summarized recent research progresses of two-dimensional layered organic-inorganic hybrid perovskite materials and their photovoltaic performances in 2D perovskite solar cells.     

锡钙钛矿太阳能电池的进展与展望

金属卤素钙钛矿是目前最有前景的高效低成本新型太阳能电池材料,但是目前还存在环境友好性和理论效率极限较低的问题。锡钙钛矿环境友好,而且其带隙更窄理论转换效率更高,吸引了广泛的关注。锡钙钛矿太阳能电池(TPSC)近年来发展迅速,是目前效率最高的无铅钙钛矿太阳能电池。本文先介绍了锡钙钛矿的晶体结构、能带结构和光电性质,然后总结了最近在锡钙钛矿领域有代表性的工作和提高光电转化效率的策略,最后讨论了锡钙钛矿发展面临的挑战和未来的发展方向。     

卤化钙钛矿太阳能电池的缺陷容忍及缺陷钝化研究进展

缺陷在钙钛矿太阳能电池的快速发展中起着至关重要的作用。缺陷容忍性,即金属卤化钙钛矿的主导缺陷是浅能级缺陷,它们不会成为强非辐射复合中心,这被认为是金属卤化钙钛矿的独特特性,是其具有高光电转换效率的主要原因。然而,要进一步提高金属卤化钙钛矿的光电转换效率,就需要消除一些可作为非辐射复合中心并严重影响器件性能的少量深能级缺陷,包括点缺陷、晶界、表面和界面等。本文综述了缺陷容忍的研究进展,包括软声子模式和极化子效应。此外,还总结了缺陷钝化的策略,包括通过阳离子或阴离子来钝化离子键,以及通过路易斯酸或路易斯碱来钝化配位键等。     

Quasi-solid-state dye-sensitized solar cells assembled by in-situ chemical cross-linking at ambient temperature

Cross-linked gel polymer electrolytes containing aluminum oxide nanoparticles are successfully prepared using in-situ chemical cross-linking at room temperature after injection of the gel precursor into a dye-sensitized solar cell (DSSC). This makes it possible to directly solidify the electrolyte in the cell without leakage of solvent and to maintain close interfacial contact with the porous TiO₂ electrode. The quasi-solid-state DSSC assembled with gel polymer electrolyte containing 20 wt.% Al₂O₃ particles yields an overall conversion efficiency of 5.25% under AM 1.5 illumination at 100 mW cm^{− 2}.     

Post-modification using aluminum isopropoxide after dye-sensitization for improved performance and stability of quasi-solid-state solar cells

In this study, dye-sensitized TiO₂ electrodes were immersed into a solution of aluminum isopropoxide and after hydrolysis quasi-solid-state solar cells were fabricated. The interaction between the dye and the resulting Al₂O₃ overlayer was investigated by ultraviolet–visible (UV–vis) spectrum, Fourier transform infrared (FTIR) spectrum and X-ray photoelectron spectrum (XPS). The current density–voltage (I–V) characteristics showed that the overlayer increased the photovoltage and decreased the photocurrent under low intensity irradiation, and increased both the photovoltage and photocurrent under AM 1.5 irradiation. The Al₂O₃ overlayer at the dye/electrolyte interface resulted in a 28% improvement in overall photo-to-electrical conversion efficiency from 2.60 to 3.32%. Dark current measurements showed that Al₂O₃ acted as an insulator barrier to retard recombination between the TiO₂ and dye/quasi-solid-state electrolyte interface. Without encapsulation, dye-sensitized solar cells with Al₂O₃ coating after sensitization also exhibited improved stability compared to cells without coating.     

A first-principle study of the stability and electronic properties of halide inorganic double perovskite Cs2PbX6 (X = Cl,I) for solar cell application

The problem of lead toxicity in perovskites materials that are currently performing with the most efficiency can be partially solved by choosing double perovskites compounds Cs₂PbX₆ (X = Cl,I), which have considerably reduced lead contents. These materials are slightly more stable, and substituting Cl and I with Br in small percentages further improves their mechanical stability and electronic properties. In this study, the properties of these promising materials were investigated in their pure and mixed forms.     

两亲性季铵盐对钙钛矿太阳能电池效率和稳定性的影响

将廉价易得的两亲性季铵盐十六烷基三甲基溴化铵（CTMAB）加入到钙钛矿前驱体溶液中,通过调节添加量研究了CTMAB对钙钛矿太阳能电池效率和稳定性的影响.结果表明,加入CTMAB后制备的钙钛矿薄膜更加致密均匀,表面缺陷更少,钙钛矿晶体结晶性得到显著提高,从而提高了电池的光电转换效率及电池稳定性;含有CTMAB的钙钛矿太阳能电池的光电转换效率（PCE）为18.03%,明显高于未添加CTMAB的电池效率（17.05%）;含有CTMAB的电池稳定性有较大的提高,在一定湿度环境中保存40 d后效率仍达初始效率的95%,而未添加CTMAB的器件效率只有初始效率的70%.     

Thermogravimetric analysis of SPEEK membranes: Thermal stability, degree of sulfonation and cross-linking reaction

Thermal degradation of SPEEK membranes is studied by coupling thermogravimetric analysis (TGA) and mass spectrometry (MS). Main mass losses can be attributed to water evaporation, desulfonation and oxidative pyrolysis of polymer main chain. The analysis can be used to determine the degree of sulfonation (DS) and the degree of cross-linking (DCL) between macromolecular chains. Furthermore, the thermogravimetric curves can be modelled using non-isothermal chemical kinetics, allowing determination of activation energies during thermal degradation of SPEEK membranes.     

Halide Chemistry in Tin Perovskite Optoelectronics: Bottlenecks and Opportunities

Tin halide perovskites (Sn HaPs) are the top lead-free choice for perovskite optoelectronics, but the oxidation of perovskite Sn²⁺ to Sn⁴⁺ remains a key challenge. However, the role of inconspicuous chemical processes remains underexplored. Specifically, the halide component in Sn HaPs (typically iodide) has been shown to play a key role in dictating device performance and stability due to its high reactivity. Here we describe the impact of native halide chemistry on Sn HaPs. Specifically, molecular halogen formation in Sn HaPs and its influence on degradation is reviewed, emphasising the benefits of iodide substitution for improving stability. Next, the ecological impact of halide products of Sn HaP degradation and its mitigation are considered. The development of visible Sn HaP emitters via halide tuning is also summarised. Lastly, halide defect management and interfacial engineering for Sn HaP devices are discussed. These insights will inspire efficient and robust Sn HaP optoelectronics.     

Inorganic p-type semiconductors and carbon materials based hole transport materials for perovskite solar cells

Incorporation of proper inorganic p-type semiconductors as hole transport layer has great potential to increase long-term stability while maintaining high power conversion efficiency of perovskite solar cells with low material cost.