醋酸纤维素提高CsPbIBr2无机钙钛矿薄膜质量及其太阳能电池光电性能

由于具有适合的带隙和较高的稳定性,CsPbIBr₂无机钙钛矿被认为是一种较有前景的太阳能电池光吸收材料.但是目前报道的CsPbIBr₂钙钛矿太阳能电池效率还偏低,主要原因是制备的CsPbIBr₂钙钛矿膜质量差、缺陷多.本文通过将醋酸纤维素(CA)加入CsPbIBr₂钙钛矿前驱体溶液中改善CsPbIBr₂钙钛矿结晶过程,从而制备高质量的CsPbIBr₂钙钛矿膜.实验结果表明,CA中的C=O基团与前驱体溶液中的Pb²⁺间存在明显的相互作用,这种相互作用结合CA加入引起的前驱体溶液粘度增加,使CsPbIBr₂钙钛矿的结晶速率明显降低,从而制备了致密、结晶度高、晶粒尺寸大、晶界和缺陷少的高质量CsPbIBr₂钙钛矿膜.同时,CA的保护作用显著提高了CsPbIBr₂钙钛矿膜的稳定性.用碳材料层作为空穴传输层和背电极,制备结构为FTO/TiO₂/CsPbIBr...     

Sputtered SnO2 as an interlayer for efficient semitransparent perovskite solar cells

SnO₂ is widely used as the electron transport layer (ETL) in perovskite solar cells (PSCs) due to its excellent electron mobility, low processing temperature, and low cost. And the most common way of preparing the SnO₂ ETL is spin-coating using the corresponding colloid solution. However, the spin-coated SnO₂ layer is sometimes not so compact and contains pinholes, weakening the hole blocking capability. Here, a SnO₂ thin film prepared through magnetron-sputtering was inserted between ITO and the spin-coated SnO₂ acted as an interlayer. This strategy can combine the advantages of efficient electron extraction and hole blocking due to the high compactness of the sputtered film and the excellent electronic property of the spin-coated SnO₂. Therefore, the recombination of photo-generated carriers at the interface is significantly reduced. As a result, the semitransparent perovskite solar cells (with a bandgap of 1.73 eV) based on this double-layered SnO₂ demonstrate a maximum efficiency of 17.7% (stabilized at 17.04%) with negligible hysteresis. Moreover, the shelf stability of the device is also significantly improved, maintaining 95% of the initial efficiency after 800-hours of aging.     

Reveal the large open-circuit voltage deficit of all-inorganicCsPbIBr2 perovskite solar cells

Due to excellent thermal stability and optoelectronic properties, all-inorganic perovskite is one of the promising candidates to solve the thermal decomposition problem of conventional organic—inorganic hybrid perovskite solar cells (PSCs), but the larger voltage loss (V_loss) cannot be ignored, especially CsPbIBr₂, which limits the improvement of efficiency. To reduce V_loss, one promising solution is the modification of the energy level alignment between the perovskite layer and adjacent charge transport layer (CTL), which can facilitate charge extraction and reduce carrier recombination rate at the perovskite/CTL interface. Therefore, the key issues of minimum V_loss and high efficiency of CsPbIBr₂-based PSCs were studied in terms of the perovskite layer thickness, the effects of band offset of the CTL/perovskite layer, the doping concentration of the CTL, and the electrode work function in this study based on device simulations. The open-circuit voltage (V_oc) is increased from 1.37 V to 1.52 V by replacing SnO₂ with ZnO as the electron transport layer (ETL) due to more matching conduction band with the CsPbIBr₂ layer.     

准二维钙钛矿太阳能电池的研究进展

目前,钙钛矿太阳能电池的光电转换效率已超过25％,飞速提升的效率使得人们越来越期待商业化的应用,但钙钛矿材料的稳定性问题却是其商业化所面临的最大挑战,准二维钙钛矿有望解决这一问题.利用大的有机间隔阳离子的疏水性和热稳定性,以及更高的晶体形成能和更加稳固的结构,准二维钙钛矿能够有效提高钙钛矿的稳定性.此外,准二维钙钛矿对...     

Advances in stable and flexible perovskite solar cells

Roll-to-roll (R2R) production is an innovative approach and is fast becoming a very popular industrial method for high throughput and mass production of solar cells. Replacement of costly indium tin oxide (ITO), which conventionally has served as the transparent electrode would be a great approach for roll to roll production of flexible cost effective solar cells. Indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) are brittle and ultimately limit the device flexibility. Perovskite solar cells (PSCs) have been the centre of photovoltaic research community during the recent years owing to its exceptional performance and economical prices. The best reported PSCs fabricated by employing mesoporous TiO₂ layers require elevated temperatures in the range of 400–500 °C which limits its applications to solely glass substrates. In such a scenario developing flexible PSCs technology can be considered a suitable and exciting arena from the application point of view, them being flexible, lightweight, portable, and easy to integrate over both small, large and curved surfaces.     

Applications and functions of rare-earth ions in perovskite solar cells

The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.     

无铅和少铅的有机-无机杂化钙钛矿太阳电池研究进展

基于有机-无机杂化卤化铅材料的钙钛矿太阳电池的转换效率在短短几年内已迅速突破22%,为未来能源问题的解决带来了曙光,同时也引起了高度重视.但紧随其后的商品化、产业化发展需求极大地增加了对绿色、无毒的高效无铅钙钛矿太阳电池进行研究和开发的重要性和紧迫性.为进一步加快环境友好型钙钛矿太阳电池的研发进度,对目前无铅和少铅钙钛矿太阳电池的发展现状进行了综述.着重讨论了替代元素种类及其浓度、制备工艺等对薄膜和电池性能的影响,以期对电池的工作机理、替代元素的作用机理有更加深刻的认识,为新型环保、高效的钙钛矿太阳电池的制备提供指导.     

肖特基钙钛矿太阳电池结构设计与优化

有机-无机杂化钙钛矿材料有高吸收系数、低廉的制作成本以及较为简单的制备工艺,在近年来表现出良好的发展前景.本文采用wx-AMPS模拟软件对平面结构钙钛矿太阳电池和肖特基钙钛矿太阳电池进行建模仿真对比,从理论上分析无载流子传输层的肖特基钙钛矿太阳电池的优势.结果显示,器件两侧电极功函数和吸收层的能带分布是提高太阳电池效率的关键.在对电极使用Au(功函数为5.1 eV)的前提下,透明导电电极功函数为3.8 eV,可以得到肖特基钙钛矿太阳电池转换效率为17.93%.对器件模型吸收层进行优化,通过寻找合适的掺杂浓度,抑制缺陷密度,确定合适的厚度,可以获得理想的转换效率(20.01%),是平面异质结结构(理论转换效率31%)的63.84%.肖特基钙钛矿太阳电池在简单的器件结构下可以获得优异的光电性能,具有较好的应用潜力.     

Optical simulation of CsPbI3/TOPCon tandem solar cells with advanced light management

Monolithic perovskite/Si tandem solar cells (TSCs) have experienced rapid development in recent years, demonstrating its potential to exceed the Shockley-Queisser limit of single junction Si solar cells. Unlike typical organic-inorganic hybrid perovskite/silicon heterojunction TSCs, here we propose CsPbI₃/TOPCon TSC, which is a promising architecture in consideration of its pleasurable thermal stability and good compatibility with current PERC production lines. The optical performance of CsPbI₃/TOPCon TSCs is simulated by the combination of ray-tracing method and transfer matrix method. The light management of the CsPbI₃/TOPCon TSC begins with the optimization of the surface texture on Si subcell, indicating that a bifacial inverted pyramid with a small bottom angle of rear-side enables a further minimization of the optical losses. Current matching between the subcells, as well as the parasitic absorption loss from the front transparent conductive oxide, is analyzed and discussed in detail. Finally, an optimized configuration of CsPbI₃/TOPCon TSC with a 31.78% power conversion efficiency is proposed. This work provides a practical guidance for approaching high-efficiency perovskite/Si TSCs.     

Surface modulation of halide perovskite films for efficient and stable solar cells

As the main distribution place of deep-level defects and the entrance of water, the interface is critical to determining both the power conversion efficiency (PCE) and the stability of perovskite solar cells (PSCs). Suitable interface design can dramatically passivate interface defects and optimize energy level alignment for suppressing the nonradiative recombination and effectively extracting the photogenerated carriers towards higher PCE. Meanwhile, a proper interface design can also block the interface diffusion of ions for high operational stability. Therefore, interface modification is of great significance to make the PSCs more efficient and stable. Upon optimized material choices, the three-dimensional halide perovskite graded junction layer, low-dimensional halide perovskite interface layer and organic salt passivation layer have been constructed on perovskite films for superior PSCs, yet a systematic review of them is missing. Thus, a guide and summary of recent advances in modulating the perovskite films interface is necessary for the further development of more efficient interface modification.     

Nano Ag-enhanced photoelectric conversion efficiency in all-inorganic,hole-transporting-layer-free CsPbIBr2 perovskite solar cells

All-inorganic, hole-transporting-layer-free CsPbIBr₂ perovskite solar cells have great potential for development, but their device performance needs to be further improved. Recently, metal nanostructures have been successfully applied in the field of solar cells to improve their performance. Nano Ag-enhanced power conversion efficiency (PCE) in one CsPbIBr₂ perovskite solar cell utilizing localized surface plasmons of Ag nanoparticles (NPs) on the surface has been researched experimentally and by simulation in this paper. The localized surface plasmon resonance of Ag NPs has a near-field enhancement effect, which is expected to improve the light absorption of CsPbIBr₂ perovskite photovoltaic devices. In addition, Ag NPs have a forward-scattering effect on the incident light, which can also improve the performance of CsPbIBr₂-based perovskite photovoltaic devices. By directly assembling Ag NPs (with a size of about 150 nm) on the surface of fluorine-doped tin oxide it is found when the particle surface coverage is 10%, the CsPbIBr₂ perovskite photovoltaic device achieves a best PCE of 2.7%, which is 9.76% higher than that of the control group. Without changing any existing structure in the ready-made solar cell, this facile and efficient method has huge applications. To the best of our knowledge, this paper is the first report on nano Ag-enhanced photoelectric conversion efficiency in this kind of CsPbIBr₂ perovskite solar cell.     

Improving the performance of perovskite solar cells with glycerol-doped PEDOT:PSS buffer layer

In this paper, we investigate the effects of glycerol doping on transmittance, conductivity and surface morphology of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate))(PEDOT:PSS) and its influence on the performance of perovskite solar cells.. The conductivity of PEDOT:PSS is improved obviously by doping glycerol. The maximum of the conductivity is 0.89 S/cm when the doping concentration reaches 6 wt%, which increases about 127 times compared with undoped. The perovskite solar cells are fabricated with a configuration of indium tin oxide(ITO)/PEDOT:PSS/CH_3NH_3PbI_3/PC_(61)BM/Al, where PEDOT:PSS and PC_(61)BM are used as hole and electron transport layers, respectively. The results show an improvement of hole charge transport as well as an increase of short-circuit current density and a reduction of series resistance, owing to the higher conductivity of the doped PEDOT:PSS. Consequently, it improves the whole performance of perovskite solar cell. The power conversion efficiency(PCE) of the device is improved from 8.57% to 11.03% under AM 1.5 G(100 mW/cm~2 illumination) after the buffer layer has been modified.     

Recent advances of interface engineering in inverted perovskite solar cells

Perovskite solar cells (PSCs) have witnessed great achievement in the past decade. Most of previous researches focus on the n—i—p structure of PSCs with ultra-high efficiency. While the n—i—p devices usually used the unstable charge transport layers, such as the hygroscopic doped spiro-OMeTAD, which affect the long-term stability. The inverted device with the p—i—n structure owns better stability when using stable undoped organic molecular or metal oxide materials. There are significant progresses in inverted PSCs, most of them related to charge transport or interface engineering. In this review, we will mainly summarize the inverted PSCs progresses related to the interface engineering. After that, we prospect the future direction on inverted PSCs.     

Importance of PbI_2 morphology in two-step deposition of CH_3NH_3PbI_3 for high-performance perovskite solar cells

Controlling the morphology of the perovskite film is an effective way to improve the photoelectric conversion efficiency of solar cell devices. In this work, we study the influence of the crystallization condition on PbI_2 morphology and the performances of resulting perovskite solar cells. The PbI_2 morphologies and coverage rates under different formation conditions such as solvent effect, slow crystallization at room temperature and substrate-preheating, are found to be of crucial importance for preparing high-quality perovskite. The generation of loosely packed disk-like PbI_2 film with interpenetrating nanopores promotes the penetration of methyl ammonium iodide(MAI), leading to a better crystallinity of the perovskite film, and a best repeatable power conversion efficiency of 11.59% is achieved when methyl ammonium lead triiodide(CH_3NH_3PbI_3, MAPbI_3) is employed. In addition, an excellent device is also obtained with an efficiency of more than 93% to remain after working for 43 days.     

Non-peripherally octaalkyl-substituted nickel phthalocyanines used as non-dopant hole transport materials in perovskite solar cells

This report presents two non-perihperally octaalkyl-substituted nickel phthalocyanines (NiPcs), namely, NiEt₂Pc and NiPr₂Pc, for use as dopant-free hole transport materials in perovskite solar cells (PSCs). The length extension of the alkyl chains from ethyl to propyl significantly tunes the NiPcs' energy levels, thus reducing charge carrier recombination at the perovskite/hole transport layer (HTL) interface and leading to higher open-circuit voltage (V_OC) and short-circuit current density (J_SC) observed for the NiPr₂Pc-based PSC. And higher charge carrier mobility, higher thin film crystallinity, and lower surface roughness of the NiPr₂Pc HTL compared with that of the NiEt₂Pc one also lead to higher J_SC and fill factor (FF) observed for the NiPr₂Pc-based device. Consequently, the NiPr₂Pc-based PSC exhibits a higher power conversion efficiency (PCE) of 14.07% than that of the NiEt₂Pc-based device (8.63%).     

新型碳材料在钙钛矿太阳电池中的应用研究进展

新型碳材料如石墨烯及其氧化物、碳纳米管、富勒烯及石墨炔等因其优异的热学、力学、电学、光学性能成为了钙钛矿太阳电池研究的又一亮点. 本文总结了新型碳材料在钙钛矿太阳电池对电极、电子传输材料及空穴传输材料中的研究进展, 新型碳材料的引入有效地提高了钙钛矿电池的性能, 为下一步新型碳材料的应用开发以及钙钛矿电池器件的研究提供了新的思路.     

十二烷二酸修饰TiO_2电子传输层改善钙钛矿太阳电池的电流特性

在经典的平面异质结钙钛矿太阳电池中,TiO_2致密层的电子传输性能一直是获得优异光伏性能的决定性因素之一.相较于spriro-OMe TAD等常见的空穴传输材料优异的空穴传输能力,作为电子传输材料的TiO_2的导电性较弱,无法形成良好的电荷匹配.为了解决这个问题,我们使用自组装的十二烷二酸(DDDA)单分子层来修饰TiO_2致密层的表面,TiO_2致密层的导电性能得到大幅提升,并且其能带结构得到优化,促进了电子传输,降低了电子积聚和载流子复合,使得电池的短路电流密度(JSC)从修饰前的20.34 mA·cm~(-2)提升至修饰后的23.28 mA·cm~(-2),进而使得电池在标准测量条件下的光电能量转换效率从14.17%提升至15.92%.同时还发现,通过DDDA修饰TiO_2致密层,所制备的器件的光稳定性显著提升,器件未封装暴露在AM 1.5光强100 mW·cm~(-2)的模拟太阳光下超过720 min,保持初始效率的71%以上且趋于稳定.     

Modulation of light absorption by optical spacer in perovskite solar cells

Lead halide perovskite solar cells with planar heterojunction configuration have recently attracted tremendous attention because of their excellent power conversion efficiencies. The modulation of optical absorption by using an optical spacer layer is a unique method to enhance the device efficiency. Here, we demonstrate the application of thin ZnO layer that act as an optical spacer that enhance the power conversion efficiency perovskite devices from 8.92% to 10.7%, which is mainly due to increment in short‐circuit current density by 16% compared to the reference solar cell. The simulation data revealed that ZnO acts as an optical spacer layer that shifts length (average) of electric field |E|² distribution from 500 nm to 750 nm wavelength is 25 nm in the perovskite layer. Which represents that exciton generation region is moved to near the hole transport layer that enhances the exciton dissociation efficiency and device efficiency.     

蒸汽辅助溶液过程制备钙钛矿材料及钙钛矿太阳能电池

有机无机杂化钙钛矿材料被广泛应用于光电器件领域,特别是其作为太阳能电池的吸光材料,受到学术界和工业界越来越多的关注。钙钛矿太阳能电池的产业化进程正在进行中,而在进一步降低制备成本、提高电池转换效率的同时,研究出一种操作简单且可重复性高的制备钙钛矿薄膜的技术具有十分重要的意义。与其他传统的溶液处理方法不同,蒸汽辅助溶液过程(VASP)处理法避免了薄膜在生长过程中溶解以及溶剂化作用,抑制了晶核的形成,使薄膜快速重组,获得致密的高质量钙钛矿薄膜。目前报道,基于此薄膜制备的平面结构钙钛矿太阳能电池转换效率高达16.8%。本文综述了低温(150℃)VASP法制备的钙钛矿薄膜及光伏器件的相关研究进展,并对该技术的产业化前景做了展望。VASP制备过程简单、薄膜性能优异且可重复性高,为进一步制备大面积、高质量薄膜提供了可能。     

钙钛矿薄膜气相制备的晶粒尺寸优化及高效光伏转换

钙钛矿薄膜的气相制备是一种极具潜力的工业化生产工艺,但薄膜的质量控制目前远落后于溶液制备法.本文通过建立PbI_2薄膜向钙钛矿薄膜完全转化过程中反应时间、晶粒尺寸与温度的关系,实现了薄膜的质量优化及大面积钙钛矿薄膜的制备,将薄膜的平均晶粒粒径从0.42μm优化到0.81μm.基于空间电荷限制电流模型对缺陷密度的研究显示,钙钛矿薄膜的缺陷密度由5.90×10~(16)cm~(–3)降低到2.66×10~(16)cm~(–3).光伏器件(FTO/TiO_2/C_(60)/MAPbI_3/spiro-OMeTAD/Au结构)测试显示,面积为0.045cm~2器件的平均光电转换效率从14.00%提升到17.42%,最佳光电转换效率达到17.80%,迟滞因子减小至4.04%.同时,基于180℃制备的1cm~2器件的光电转换效率达到13.17%.