ZnO/GO纳米材料基热稳定钙钛矿太阳能电池（英文）

为了使钙钛矿太阳能电池在高温退火后能够保持稳定,本研究通过电化学方法制备出氧化锌/氧化石墨烯纳米粒子,并将其运用到钙钛矿太阳能电池中作为电子传输层使用。通过原位掠入射X射线衍射(GIXRD)、X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外–可见吸收光谱(UV-Vis)等方法对沉积在氧化锌和氧化锌/氧化石墨烯纳米材料上面的甲胺铅碘的结构、形貌以及电池性能变化进行分析测试。结果表明:氧化锌/氧化石墨烯对于甲胺铅碘有保护作用,沉积在氧化锌/氧化石墨烯上面的甲胺铅碘薄膜稳定性更高,电池性能更加稳定,为将来大面积应用提供了一定的指导。     

基于氧化石墨烯空穴传输层的平面异质结钙钛矿太阳能电池

钙钛矿太阳能电池中传统空穴传输层Spiro-OMeTAD存在昂贵、易污染环境且制备困难等缺点,本工作采用氧化石墨烯(Graphene oxide,GO)作为空穴传输层,研究了不同浓度GO溶液制备的衬底对器件光电性能的影响.首先,采用旋涂法制备了GO薄膜,通过对分散液浓度的控制获得了不同厚度的GO衬底.其次,制备了结构为ITO/GO/CH3 NH3 PbI3/PCBM/Ag的平面型器件,对不同GO衬底的器件的光电性能进行表征及对比分析.研究表明:GO衬底缺陷会抑制CH3 NH3 PbI3晶粒的择优取向生长,形成可诱导CH3 NH3 PbI3晶粒产生横向聚集的籽晶,从而改善钙钛矿薄膜的成膜性,并增大钙钛矿晶粒尺寸.由浓度为0.25 mg/mL的分散液制备的GO薄膜衬底上生长的钙钛矿晶粒尺寸最大为900 nm.此外,该浓度对应的GO衬底上制备的钙钛矿薄膜的光致发光相对强度峰值为2000,电荷转移效率相对最高,为52.8％.由该衬底制备的GO基钙钛矿太阳能电池的光电转化效率最高可提升至8.69％.     

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%。     

ZnO薄膜的同质外延生长及其结构表征

利用等离子体辅助分子束外延的方法在ZnO单晶衬底上制备了ZnO薄膜。利用X射线衍射(XRD)、同步辐射掠入射XRD和φ扫描等实验技术研究了ZnO薄膜的结构。XRD和φ扫描的结果显示同质外延的ZnO薄膜已经达到单晶水平。掠入射XRD结果表明ZnO薄膜内部不同深度处a方向的晶格弛豫是不一致的,从接近衬底界面处到薄膜的中间部分再到薄膜的表面处,a方向的晶格常数分别为0.3249,0.3258和0.3242 nm。计算得到ZnO薄膜的泊松比为0.156,同质外延的ZnO薄膜与衬底在a轴方向的晶格失配度为-0.123%。     

碳材料在钙钛矿太阳能电池中的应用

钙钛矿太阳能电池具有材料成本低廉、生产工艺简单、光电转换效率高等优点,发展前景十分光明。碳材料因其价格低廉、高导电性、疏水性和化学稳定性等特点,被应用在钙钛矿太阳能电池的各个组成部分,用于提高电池性能和降低成本。本文根据应用在钙钛矿太阳能电池中的碳材料的维数进行分类,分别介绍了零维的C60、碳量子点和石墨烯量子点,一维的碳纳米管,二维的石墨烯及其衍生物、石墨炔和三维的石墨等在钙钛矿太阳能电池中的应用,对于将来实现钙钛矿太阳能电池的低成本商业化和大规模制造具有重要意义。     

6H-SiC单晶表面ZnO薄膜的制备及其结构表征

利用脉冲激光淀积(PLD)技术在6H-SiC单晶衬底上制备了ZnO薄膜. 利用X射线衍射(XRD), 反射式高能电子衍射(RHEED)和同步辐射掠入射X射线衍射(SRGID)φ扫描等实验技术研究了ZnO薄膜的结构. 结果表明:在单晶6H-SiC衬底上制备的ZnO薄膜已经达到单晶水平, 不同入射角的SRGID结果, 显示了ZnO薄膜内部不同深度处a方向的晶格弛豫是不一致的, 从接近衬底界面处到薄膜的中间部分再到薄膜的表面处, a方向的晶格常数分别为0.3264、0.3272和0.3223nm. 通过计算得到ZnO薄膜的泊松比为0.504, ZnO薄膜与单晶6H-SiC衬底在平行于衬底表面a轴方向的实际晶格失配度为5.84%.     

高稳定性(EDA)(FA)2[Pb3I10]层状钙钛矿薄膜的制备与表征

为了提高钙钛矿太阳能电池在潮湿环境中的稳定性, 采用一步法, 通过在DMF中混合(EDA)I₂、(FA)I和PbI₂, 将乙二胺离子引入钙钛矿晶格, 成功制备了一种具有较高稳定性的二维片层状的钙钛矿结构薄膜。通过原位掠入射X射线衍射(GIXRD)、X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)和原子力显微镜(AFM)等方法检测分析(EDA)(FA)₂[Pb₃I₁₀]在低湿度及高湿度环境下的结构、形貌以及光学性能变化。结果表明: 制备的 (EDA)(FA)₂[Pb₃I₁₀]薄膜在相同湿度环境下比当前广泛应用于钙钛矿太阳能电池的甲胺铅碘薄膜(CH₃NH₃PbI₃)稳定性更高; 薄膜的光学带隙约为1.67 eV, 与太阳能电池最佳带隙比较接近。另外, (EDA)(FA)₂[Pb₃I₁₀]薄膜在可见光范围吸光性能较好; 薄膜的粗糙度很小, 适合制备太阳能电池, 而且, 成本较硅基太阳能电池低廉, 在分子水平较CH₃NH₃PbI₃的可调谐性更大, 使钙钛矿太阳能电池在未来大面积应用成为可能。     

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。     

倒置结构全无机钙钛矿太阳能电池的界面层研究进展

铯基无机钙钛矿(CsPbX3)因其耐热性好、低成本和带隙可调等优点,近年来备受关注,并广泛用于制备新型薄膜太阳能电池。目前,虽然具有倒置结构的无机钙钛矿太阳能电池(PSC)更稳定且有望应用于构筑叠层电池的顶电池,其性能仍落后于正置结构的电池。因此,倒置电池的结构,特别是其界面层亟待进一步优化。近年来,研究者们设计和开发了一系列有机、无机界面层(包括空穴传输层和电子传输层),尝试优化基于无机钙钛矿的倒置电池。本综述针对这一现状,从材料和制备工艺的角度出发,综述了基于有机、无机材料体系的多种界面层的制备和应用进展,总结各类界面层材料的特点,讨论目前界面层的瓶颈问题和潜在的解决方案。     

Red-Carbon-Quantum-Dot-Doped SnO2 Composite with Enhanced Electron Mobility for Efficient and Stable Perovskite Solar Cells

An efficient electron transport layer (ETL) plays a key role in promoting carrier separation and electron extraction in planar perovskite solar cells (PSCs). An effective composite ETL is fabricated using carboxylic-acid- and hydroxyl-rich red-carbon quantum dots (RCQs) to dope low-temperature solution-processed SnO₂, which dramatically increases its electron mobility by ≈20 times from 9.32 × 10⁻⁴ to 1.73 × 10⁻² cm² V⁻¹ s⁻¹. The mobility achieved is one of the highest reported electron mobilities for modified SnO₂. Fabricated planar PSCs based on this novel SnO₂ ETL demonstrate an outstanding improvement in efficiency from 19.15% for PSCs without RCQs up to 22.77% and have enhanced long-term stability against humidity, preserving over 95% of the initial efficiency after 1000 h under 40–60% humidity at 25 °C. These significant achievements are solely attributed to the excellent electron mobility of the novel ETL, which is also proven to help the passivation of traps/defects at the ETL/perovskite interface and to promote the formation of highly crystallized perovskite, with an enhanced phase purity and uniformity over a large area. These results demonstrate that inexpensive RCQs are simple but excellent additives for producing efficient ETLs in stable high-performance PSCs as well as other perovskite-based optoelectronics.     

Indium‐Free Perovskite Solar Cells Enabled by Impermeable Tin‐Oxide Electron Extraction Layers

Corrosive precursors used for the preparation of organic–inorganic hybrid perovskite photoactive layers prevent the application of ultrathin metal layers as semitransparent bottom electrodes in perovskite solar cells (PVSCs). This study introduces tin‐oxide (SnO_x) grown by atomic layer deposition (ALD), whose outstanding permeation barrier properties enable the design of an indium‐tin‐oxide (ITO)‐free semitransparent bottom electrode (SnO_x/Ag or Cu/SnO_x), in which the metal is efficiently protected against corrosion. Simultaneously, SnO_x functions as an electron extraction layer. We unravel the spontaneous formation of a PbI₂ interfacial layer between SnO_x and the CH₃NH₃PbI₃ perovskite. An interface dipole between SnO_x and this PbI₂ layer is found, which depends on the oxidant (water, ozone, or oxygen plasma) used for the ALD growth of SnO_x. An electron extraction barrier between perovskite and PbI₂ is identified, which is the lowest in devices based on SnO_x grown with ozone. The resulting PVSCs are hysteresis‐free with a stable power conversion efficiency (PCE) of 15.3% and a remarkably high open circuit voltage of 1.17 V. The ITO‐free analogues still achieve a high PCE of 11%.     

Core/Shell ZnO/ZnS Nanoparticle Electron Transport Layers Enable Efficient All-Solution-Processed Perovskite Light-Emitting Diodes

Solution-processed perovskite-based light-emitting diodes (PeLEDs) are promising candidates for low-cost, large-area displays, while severe deterioration of the perovskite light-emitting layer occurs during deposition of electron transport layers from solution in an issue. Herein, core/shell ZnO/ZnS nanoparticles as a solution-processed electron transport layer in PeLED based on quasi-2D PEA₂Cs_n−1Pb_nBr_3n+1 (PEA = phenylethylammonium) perovskite are employed. The deposition of ZnS shell mitigates trap states on ZnO core by anchoring sulfur to oxygen vacancies, and at the same time removes residual hydroxyl groups, which helps to suppress the interfacial trap-assisted non-radiative recombination and the deprotonation reaction between the perovskite layer and ZnO. The core/shell ZnO/ZnS nanoparticles show comparably high electron mobility to pristine ZnO nanoparticles, combined with the reduced energy barrier between the electron transport layer and the perovskite layer, improving the charge injection balance in PeLEDs. As a result, the optimized PeLEDs employing core/shell ZnO/ZnS nanoparticles as a solution-processed electron transport layer exhibit high peak luminance reaching 32 400 cd m⁻², external quantum efficiency of 10.3%, and 20-fold extended longevity as compared to the devices utilizing ZnO nanoparticles, which represents one of the highest overall performances for solution-processed PeLEDs.     

Synergistic Ionic Liquid in Hole Transport Layers for Highly Stable and Efficient Perovskite Solar Cells

Perovskite solar cells (PSCs) with n-i-p structures often utilize an organic 2,2′,7,7′-tetrakis (N, N-di-p-methoxyphenyl-amine) 9,9′-spirobifluorene (spiro-OMeTAD) along with additives of lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI) and tert-butylpyridine as the hole transporting layer (HTL). However, the HTL lacks stability in ambient air, and numerous defects are often present on the perovskite surface, which is not conducive to a stable and efficient PSC. Therefore, constructive strategies that simultaneously stabilize spiro-OMeTAD and passivate the perovskite surface are required. In this work, it is demonstrated that a novel ionic liquid of dimethylammonium bis(trifluoromethanesulfonyl)imide (DMATFSI) could act as a bifunctional HTL modulator in n-i-p PSCs. The addition of DMATFSI into spiro-OMeTAD can effectively stabilize the oxidized spiro-OMeTAD⁺ cation radicals through the formation of spiro-OMeTAD⁺TFSI⁻ because of the excellent charge delocalization of the conjugated CF₃SO₂⁻ moiety within TFSI⁻. In addition, DMA⁺ cations could move toward the perovskite from the HTL, resulting in the passivation of defects at the perovskite surface. Accordingly, a power conversion efficiency of 23.22% is achieved for PSCs with DMATFSI and LiTFSI co-doped spiro-OMeTAD. Moreover, benefiting from the improved ion migration barrier and hydrophobicity of the HTL, still retained nearly 80% of their initial power conversion efficiency after 36 days of exposure to ambient air.     

Efficient,Hysteresis‐Free,and Stable Perovskite Solar Cells with ZnO as Electron‐Transport Layer: Effect of Surface Passivation

The power conversion efficiency of perovskite solar cells (PSCs) has ascended from 3.8% to 22.1% in recent years. ZnO has been well‐documented as an excellent electron‐transport material. However, the poor chemical compatibility between ZnO and organo‐metal halide perovskite makes it highly challenging to obtain highly efficient and stable PSCs using ZnO as the electron‐transport layer. It is demonstrated in this work that the surface passivation of ZnO by a thin layer of MgO and protonated ethanolamine (EA) readily makes ZnO as a very promising electron‐transporting material for creating hysteresis‐free, efficient, and stable PSCs. Systematic studies in this work reveal several important roles of the modification: (i) MgO inhibits the interfacial charge recombination, and thus enhances cell performance and stability; (ii) the protonated EA promotes the effective electron transport from perovskite to ZnO, further fully eliminating PSCs hysteresis; (iii) the modification makes ZnO compatible with perovskite, nicely resolving the instability of ZnO/perovskite interface. With all these findings, PSCs with the best efficiency up to 21.1% and no hysteresis are successfully fabricated. PSCs stable in air for more than 300 h are achieved when graphene is used to further encapsulate the cells.     

To Be Higher and Stronger—Metal Oxide Electron Transport Materials for Perovskite Solar Cells

Organometallic mixed halide perovskite solar cells (PSCs) have emerged as a promising photovoltaic technology with increasingly improved device efficiency exceeding 24%. Charge transport layers, especially electron transport layers (ETLs), are verified to play a vital role in device performance and stability. Recently, metal oxides (MOs) have been widely studied as ETLs for high‐performance PSCs due to their excellent electronic properties, superb versatility, and great stability. This Review briefly discusses the development of PSCs' architecture and outlines the requirements for MO ETLs. Additionally, recent progress of MO ETLs from preparation to optimization for efficient PSCs is systematically summarized and highlighted to associate the versatility of MO ETLs with the performance of devices. Finally, a summary and prospectives for the future development of MO ETLs toward practical application of high‐performance PSCs are drawn.     

Collaborative Passivation for Dual Charge Transporting Layers Based on 4-(chloromethyl)benzonitrile Additive toward Efficient and Stable Inverted Perovskite Solar Cells

Poor carrier transport capacity and numerous surface defects of charge transporting layers (CTLs), coupled with misalignment of energy levels between perovskites and CTLs, impact photoelectric conversion efficiency (PCE) of inverted perovskite solar cells (PSCs) profoundly. Herein, a collaborative passivation strategy is proposed based on 4-(chloromethyl) benzonitrile (CBN) as a solution additive for fabrication of both [6,6]-phenyl-C61-butyric acid methylester (PCBM) and poly(triarylamine) (PTAA) CTLs. This additive can improve wettability of PTAA and reduce the agglomeration of PCBM particles, which enhance the PCE and device stability of the PSCs. As a result, a PCE exceeding 20% with a remarkable short circuit current of 23.9 mA cm⁻², and an improved fill factor of 81% is obtained for the CBN- modified inverted PSCs. Devices maintain 80% and 70% of the initial PCE after storage under 30% and 85% humidity ambient conditions for 1000 h without encapsulation, as well as negligible light state PCE loss. This strategy demonstrates feasibility of the additive engineering to improve interfacial contact between the CTLs and perovskites for fabrication of efficient and stable inverted PSCs.     

Highly Efficient and Stable Perovskite Solar Cells via Modification of Energy Levels at the Perovskite/Carbon Electrode Interface

Perovskite solar cells (PSCs) have attracted great attention in the past few years due to their rapid increase in efficiency and low‐cost fabrication. However, instability against thermal stress and humidity is a big issue hindering their commercialization and practical applications. Here, by combining thermally stable formamidinium–cesium‐based perovskite and a moisture‐resistant carbon electrode, successful fabrication of stable PSCs is reported, which maintain on average 77% of the initial value after being aged for 192 h under conditions of 85 °C and 85% relative humidity (the “double 85” aging condition) without encapsulation. However, the mismatch of energy levels at the interface between the perovskite and the carbon electrode limits charge collection and leads to poor device performance. To address this issue, a thin‐layer of poly(ethylene oxide) (PEO) is introduced to achieve improved interfacial energy level alignment, which is verified by ultraviolet photoemission spectroscopy measurements. Indeed as a result, power conversion efficiency increases from 12.2% to 14.9% after suitable energy level modification by intentionally introducing a thin layer of PEO at the perovskite/carbon interface.