PbI2对钙钛矿薄膜及太阳电池性能的影响

碘化铅(PbI₂)是两步法制备钙钛矿薄膜最常使用的金属卤化物前驱体,精确控制PbI₂在钙钛矿薄膜中的含量和空间分布以及优化PbI₂薄膜的形貌结构对于制备高效稳定的太阳电池具有重要意义。探索了PbI₂的浓度和退火方式对钙钛矿薄膜及太阳电池性能的影响。研究发现,PbI₂溶液的浓度不仅决定钙钛矿薄膜中PbI₂的含量,也影响钙钛矿的晶粒尺寸、取向及光学吸收等性质,从而导致器件性能的改变,当钙钛矿薄膜表面分布约45%的PbI₂时器件性能更佳。此外,PbI₂的形貌、结晶性和孔隙度受退火方式的影响显著,与溶剂退火相比,通过短暂的1 min热退火制备的PbI₂薄膜更有利于减少钙钛矿表界面缺陷,提升器件的开路电压,最终使器件的基础光电转换效率(PCE)可以提升至20.89%。上述研究结果有助于进一步优化钙钛矿太阳电池制备工艺,提升器件性能。     

基于Cs2AgBiBr6卤化物双钙钛矿太阳电池的研究进展

铅基钙钛矿太阳电池的优异器件性能归因于其显著的光学和电子性质,其能量转换效率已从最初的约3.8%大幅提高到25%以上。尽管铅基钙钛矿太阳电池得到了快速的发展,但由于铅原子的毒性及其在热、光和湿度等条件下的不稳定性,阻碍了该类型钙钛矿光伏技术的实际应用。因此,寻找无铅、无毒和环保的卤化物钙钛矿来取代铅基材料在实际中的应用至关重要。无铅卤化物钙钛矿的研究是目前的研究热点之一。本文综述了无铅双钙钛矿Cs2AgBiBr6在钙钛矿太阳电池中的应用,介绍了Cs2AgBiBr6的结构与材料制备的方法,讨论了钙钛矿太阳电池的器件性能,分析了提高该类型光伏器件性能的相关策略,探讨了无铅钙钛矿面临的挑战以及发展方向。     

有机卤化物盐对钙钛矿太阳电池器件性能的影响

有机无机杂化钙钛矿已被证明是优良的光吸收材料,可用于高效率光伏领域。增大钙钛矿薄膜的晶粒尺寸和对晶界缺陷的钝化是提高太阳电池性能的重要途径。文章报道了一种简单的缺陷钝化技术,将有机卤化物盐BAI引入钙钛矿的混合阳离子中,以起到增大晶粒和钝化缺陷的作用,使钙钛矿太阳电池的光电转换效率从19.46%提升至21.56%。这种效率的提升是在不损失短路电流和填充因子的情况下,开路电压从1.04V提高到1.11V的结果。这种提升钙钛矿型太阳电池开路电压的方法,为进一步提高钙钛矿型太阳电池的光电性能提供了新的途径。     

GaInP2/GaAs/Ge叠层太阳电池中的高效率Ge底电池

从电池的结构参数及器件工艺等方面分析了Ge底电池的开路电压Voc、短路电流Isc和填充因子FF的影响.结果表明控制发射层的表面复合,并减薄其厚度可以提高开路电压Voc,并可以有效提高短路电流Isc;调整相应的器件工艺有利于填充因子FF的提高.采用上述改进措施,成功得到Voc达到287.5mV,Isc达到73.13mA/cm2,效率达到7.35%的Ge太阳电池.     

钙钛矿太阳电池CsPbI3的相稳定性研究进展

对全无机CsPbI3钙钛矿材料在光伏电池、发光二极管等光电器件领域的优势以及目前室温下钙钛矿相CsPbI3存在的相不稳定性问题进行了简单的阐述,重点从相不稳定的原理性分析和外部影响因素入手,包括理论分析、结构特性、温度和湿度这四个方面系统分析了 CsPbI3钙钛矿相极易转变为非钙钛矿相的原因,并结合CsPbI3钙钛矿的...     

TiO2掺杂量对TZO陶瓷靶材性能的影响

用常压烧结方法制备了掺钛氧化锌(TZO)陶瓷靶材,研究了TiO2掺杂量对TZO靶材的微观形貌、相对密度、抗弯强度和电阻率的影响。结果表明:添加适量TiO2利于TZO靶材的致密化,掺杂过量TiO2会使TZO陶瓷中析出Zn2TiO4;随TiO2掺杂量增大,靶材的相对密度和抗弯强度先增大后减小,电阻率则先减小后增大。当w(TiO2)为1.5%时,靶材相对密度获得最大值98.32%;当w(TiO2)为1.0%时,所制靶材抗弯强度最大(98.39 MPa),电阻率最小(2.586×10–3·cm),且其相对密度为98%。     

Cu2ZnSn(S,Se)4薄膜太阳电池研究进展

Cu2ZnSn(S,Se)4(CZTS)材料具有与Cu(In,Ga)Se2(CIGS)材料相似的光学性质和半导体性质,且原料丰富,是CIGS薄膜太阳电池重要的后备材料。有关CZTS薄膜制备工艺的研究和电池器件转换效率提升的研究正成为本领域新的研究开发热点。目前,有实力的薄膜太阳电池研究队伍已经针对CZTS薄膜太阳电池开展了持续的研究,试图通过不同的CZTS吸收层制备方式和优化电池组装工艺过程,进一步提高CZTS薄膜太阳电池的光电转换效率。文章阐述了CZTS材料特性,着重介绍了目前国内外所采用的CZTS薄膜制备方法,详细讨论了各种薄膜沉积技术的优缺点。最后展望了CZTS电池的发展趋势。     

激光预处理对HfO2光学薄膜微观性能的影响

研究了在1-on-1方式下激光预处理对HfO₂光学薄膜微观形貌、微观结构等性能的影响。实验采用薄 膜阈值能量的10%、50%%对HfO₂薄膜进行激光预处理,利用原子力显微镜(AFM )分别对预处理后薄膜表面 10μm和3μm×3μm的区域进行测 试,与预处理前相比,预处理后的薄膜所含杂质减少,薄膜表面锥状结构变得平 滑;利用X射线衍射(XRD)和X射线光电子能谱(XPS)分别对预处理后薄膜的晶态结 构和化学键以及价态进 行测试,与预处理前相比,预处理后薄膜的晶态结构、化学键及价态均没有发生变化;利用 XPS对预处理后薄膜所含 的成分进行测试,与预处理前相比,预处理后薄膜中所含的Hf单质减少,HfO₂增多。实验 结果表明,激光预处理具有抛光和氧化膜层的作用。     

MgF2缓冲层对蓝光OLED性能的影响

为了提高蓝光有机电致发光器件(OLED)的发光性能,将MgF2缓冲层插入ITO阳极与空穴传输层NPB之间,通过优化MgF2的厚度,制备了结构为ITO/MgF2(x nm)/NPB(50nm)/DPVBi:DSA-ph(30nm)/Alq3(30nm)/LiF(0.6nm)/Al(100nm)的高性能蓝光器件。实验结果表明,MgF2厚为1.0nm时,器件性能最佳,对应的器件最大电流效率达到5.51cd/A,最大亮度为23 290cd/m2(10.5V),与没有MgF2缓冲层的标准器件相比,分别提高47.3%和25.2%。对ITO表面的功函数测量结果表明,MgF2缓冲层可以有效修饰ITO表面,降低ITO与NPB之间的势垒高度差,改善空穴的注入效率,从而导致电子和空穴的注入更加平衡,激发机制更高效,实现了高性能的蓝光发射,为实现高效而稳定的全彩显示和白光照明奠定了基础。     

高效柔性钙钛矿太阳电池的研究进展

钙钛矿太阳电池(PSC)具有高光电转换效率(PCE)、低成本、易采用溶液法制备等特点,在发展轻薄、便携的柔性太阳电池方面有独特优势,可用于可穿戴设备、光伏建筑等领域。由于在柔性衬底上沉积均匀和高质量的钙钛矿薄膜颇具挑战性,目前,单结柔性钙钛矿太阳电池的PCE虽已经达到24.08%,但仍落后于刚性钙钛矿太阳电池(认证PCE为26.1%);此外,柔性钙钛矿薄膜在制备和弯曲循环过程中会不可避免地产生晶界裂纹,这也为柔性钙钛矿太阳电池的稳定性和可靠性带来巨大挑战。系统地评述了提升柔性钙钛矿太阳电池PCE和稳定性的研究进展,从柔性衬底、晶粒调控、晶界增强、界面钝化及结构优化等不同角度进行了归纳总结,并对柔性钙钛矿太阳电池未来发展存在的问题和挑战进行了展望。     

Morphological Control for High Performance,Solution‐Processed Planar Heterojunction Perovskite Solar Cells

Organometal trihalide perovskite based solar cells have exhibited the highest efficiencies to‐date when incorporated into mesostructured composites. However, thin solid films of a perovskite absorber should be capable of operating at the highest efficiency in a simple planar heterojunction configuration. Here, it is shown that film morphology is a critical issue in planar heterojunction CH₃NH₃PbI_3‐xCl_x solar cells. The morphology is carefully controlled by varying processing conditions, and it is demonstrated that the highest photocurrents are attainable only with the highest perovskite surface coverages. With optimized solution based film formation, power conversion efficiencies of up to 11.4% are achieved, the first report of efficiencies above 10% in fully thin‐film solution processed perovskite solar cells with no mesoporous layer.     

In Situ Growth of 2D Perovskite Capping Layer for Stable and Efficient Perovskite Solar Cells

2D halide perovskites have recently been recognized as a promising avenue in perovskite solar cells (PSCs) in terms of encouraging stability and defect passivation effect. However, the efficiency (less than 15%) of ultrastable 2D Ruddlesden–Popper PSCs still lag far behind their traditional 3D perovskite counterparts. Here, a rationally designed 2D‐3D perovskite stacking‐layered architecture by in situ growing 2D PEA₂PbI₄ capping layers on top of 3D perovskite film, which drastically improves the stability of PSCs without compromising their high performance, is reported. Such a 2D perovskite capping layer induces larger Fermi‐level splitting in the 2D‐3D perovskite film under light illumination, resulting in an enhanced open‐circuit voltage (V_oc) and thus a higher efficiency of 18.51% in the 2D‐3D PSCs. Time‐resolved photoluminescence decay measurements indicate the facilitated hole extraction in the 2D‐3D stacking‐layered perovskite films, which is ascribed to the optimized energy band alignment and reduced nonradiative recombination at the subgap states. Benefiting from the high moisture resistivity as well as suppressed ion migration of the 2D perovskite, the 2D‐3D PSCs show significantly improved long‐term stability, retaining nearly 90% of the initial power conversion efficiency after 1000 h exposure in the ambient conditions with a high relative humidity level of 60 ± 10%.     

Recent Advances on Nanocrystals Embedding for High Performance Perovskite Solar Cells

Interfacial loss arising from defect trapping, contact barrier, and energy level alignment in the emerged perovskite solar cells (PSCs), is one of the most important issues to address for both improved photoconversion efficiency and long-term operational stability. The recent endeavors on the interfacial embedding of nanocrystals (NCs) in desired locations of PSCs have shown great success in terms of eliminating the interfacial loss in PSCs, while there is a lack of review to summarize the advances of NCs embedding for improved carrier dynamics and inhibited environmental degradation. Present study systematically analyzes the recent achievements on the embedding of a series of NCs including carbon dots, perovskite NCs, II-VI semiconductor NCs, metal/alloy NCs, which are intentionally introduced in desired layers/interfaces of PSCs. The specific functionality of the NCs embedding including carrier dynamic modulation, crystallinity enhancement, defect passivation, light trapping, and stability enhancement are sorted out, according to the requirement of each layer in PSCs. Finally, the current challenges and future perspectives of NCs embedding for perovskite-based optoelectronic devices is outlook. The present study provides a guide for developing NCs-based additives for high-performance PSCs is believed.     

Probing Molecular and Crystalline Orientation in Solution‐Processed Perovskite Solar Cells

The microstructure of solution‐processed organometallic lead halide perovskite thin films prepared by the “gas‐assisted” method is investigated with synchrotron‐based techniques. Using a combination of GIWAXS and NEXAFS spectroscopy the orientational alignment of CH₃NH₃PbI₃ crystallites and CH₃NH₃⁺ cations are separately probed. The GIWAXS results reveal a lack of preferential orientation of CH₃NH₃PbI₃ crystallites in 200–250 nm thick films prepared on both planar TiO₂ and mesoporous TiO₂. Relatively high efficiencies are observed for device based on such films, with 14.3% achieved for planar devices and 12% for mesoporous devices suggesting that highly oriented crystallites are not crucial for good cell performance. Oriented crystallites however are observed in thinner films (≈60 nm) deposited on planar TiO₂ (but not on mesoporous TiO₂) indicating that the formation of oriented crystallites is sensitive to the kinetics of solvent evaporation and the underlying TiO₂ morphology. NEXAFS measurements on all samples found that CH₃NH₃⁺ cations exhibit a random molecular orientation with respect to the substrate. The lack of any NEXAFS dichroism for the thin CH₃NH₃PbI₃ layer deposited on planar TiO₂ in particular indicates the absence of any preferential orientation of CH₃NH₃⁺ cations within the CH₃NH₃PbI₃ unit cell for as‐prepared layers, that is, without any electrical poling.     

Multifunctional Enhancement for Highly Stable and Efficient Perovskite Solar Cells

With a certified efficiency as high as 25.2%, perovskite has taken the crown as the highest efficiency thin film solar cell material. Unfortunately, serious instability issues must be resolved before perovskite solar cells (PSCs) are commercialized. Aided by theoretical calculation, an appropriate multifunctional molecule, 2,2-difluoropropanediamide (DFPDA), is selected to ameliorate all the instability issues. Specifically, the carbonyl groups in DFPDA form chemical bonds with Pb²⁺ and passivate under-coordinated Pb²⁺ defects. Consequently, the perovskite crystallization rate is reduced and high-quality films are produced with fewer defects. The amino groups not only bind with iodide to suppress ion migration but also increase the electron density on the carbonyl groups to further enhance their passivation effect. Furthermore, the fluorine groups in DFPDA form both an effective barrier on the perovskite to improve its moisture stability and a bridge between the perovskite and HTL for effective charge transport. In addition, they show an effective doping effect in the HTL to improve its carrier mobility. With the help of the combined effects of these groups in DFPDA, the PSCs with DFPDA additive achieve a champion efficiency of 22.21% and a substantially improved stability against moisture, heat, and light.     

Recent Advances in Carbon Nanotube Utilizations in Perovskite Solar Cells

Metal halide perovskite solar cells (PSCs) have emerged as promising next-generation photovoltaic devices with the maximum output efficiency exceeding 25%. Despite significant advances, there are many challenges to achieve high efficiency, stability, and low-cost simultaneously. Combating these challenges depends on developing novel materials and modifying conventional device components. Carbon nanotubes (CNTs) have attracted considerable attention for fabricating efficient PSCs owing to their remarkable electrical, optical, and mechanical properties. With their multifunctional features, CNTs can play a wide range of roles and offer unique benefits in various components in PSCs to improve device performance and durability. Here, recent progress concerning the utilizations of CNTs as transparent conductive electrodes, charge-transporter, perovskite additives, interlayers, hole-transporting materials, and back electrodes in PSCs is comprehensively reviewed. The application of CNTs toward the development of 1D and 2D flexible PSCs is also discussed. A summary of current challenges and prospective on future research directions of employing CNTs to realize high-performance PSCs is presented.     

Interface Energy-Level Management toward Efficient Tin Perovskite Solar Cells with Hole-Transport-Layer-Free Structure

Lead-free tin perovskite solar cells (PSCs) have emerged as a promising candidate toward high-performance and eco-friendly photovoltaic technology with great potential for future application. However, tin PSCs with over 10% efficiency usually feature an organic hole transport layer (HTL) at the illumination side that may induce device degradation during long-term operation. Removing the unstable organic HTL is an important way to solve these stability issues, but the efficiency of HTL-free tin PSCs is still much lower than that of the completed cells. Herein, it is demonstrated that formamidinium tin iodide doped with heterogeneous ammonium salts can form an upward band-bending structure to selectively extract the hole in the HTL-free devices. By using this band-bending structure, a promising efficiency of over 10% is first achieved for the lead-free PSCs with a HTL-free structure. More importantly, the optimized cell is highly stable, keeping 95% and 90% of the initial efficiency after continuous light soaking for 40 days and 80 °C annealing for 300 h, respectively. This work paves a route toward the development of efficient, eco-friendly, and highly stable perovskite photovoltaics.