Tailoring interface of lead-halide perovskite solar cells

Lead-halide perovskite solar cells (PSCs) have attracted tremendous attention during the past few years owing to their extraordinary electronic and photonic properties.To improve the performances of PSCs,many researchers have focused on the compositional engineering,solvent engineering,and film fabrication methodologies.Interfacial engineering of PSCs has become a burgeoning field in which researchers aim to deeply understand the mechanisms of cells and thereby increase the efficiency and stability of PSCs.This review focuses on the interface tailoring of lead-halide PSCs,including the modification of each layer of the cell structure (i.e.,perovskite absorber,electron-transport layers,and holetransport layers) and the interfacial materials that can be introduced into the PSCs.     

Recent advances on interface engineering of perovskite solar cells

Lead halide perovskite solar cells(PSCs)have been rapidly developed in the past decade.Owing to its excellent power conversion efficiency with robust and low-cost fabrication,perovskite quickly becomes one of the most promising candidates for the next-generation photovoltaic technology.With the development of PSCs,the interface engineering has witnessed its increasingly critical role in maximizing the device performance as well as the long-term stability,because the interfaces in PSCs are closely correlated with the defect management,carrier dynamics and surface passivation.This review focuses on interfacial modification between the perovskite active layer and the charge transport layer,as well as the recent advances on high-efficiency and stable PSCs driven by interface engineering strategies.The contributing roles of interface engineering in terms of defect passivation,inhibiting ion migration,optimization of energy band alignment and morphological control are discussed.Finally,based on the latest progress and advances,strategies and opportunities for the future research on interface engineering for PSCs are proposed to promote the development of perovskite photovoltaic technology.     

铅卤钙钛矿太阳能电池界面工程的近期进展

铅卤钙钛矿太阳能电池因其优良的光电转换效率以及相对低廉的制备成本而受到广泛关注。然而铅卤钙钛矿太阳能电池的长期稳定性限制了其商业化的进程。界面非辐射复合导致铅卤钙钛矿太阳能电池产生能量损失、影响器件稳定性,是造成器件性能恶化的主要原因。界面工程作为一种有效的策略被用于抑制界面非辐射复合,在制备高效稳定的铅卤钙钛矿太阳能电池方面取得了切实的成效。本文阐述了铅卤钙钛矿太阳能电池的工作原理以及界面上的非辐射复合过程,分析了界面非辐射复合产生的原因,总结了近期n-i-p正式结构铅卤钙钛矿太阳能电池中界面工程的研究进展,讨论了其作用机制。基于目前铅卤钙钛矿太阳能电池中的界面工程发展现状,对其未来的发展方向进行了展望。     

Selectively patterned TiO2 nanorods as electron transport pathway for high performance perovskite solar cells

Organic-inorganic hybrid perovskite solar cells (PSCs) are attracting tremendous attention for new-generation photovoltaic devices because of their excellent power conversion efficiency and simple fabrication process. One of the various approaches to increase the efficiency of PSCs is to change the material or structure of the carrier transport layer. Here, optically long and electrically short structural concept is proposed to enhance the characteristics of a PSC by employing selectively grown single crystalline TiO₂ nanorods. The approach has the merit of increasing the electron-hole separation effectively and enables a thicker active layer to be coated without electrical loss by using TiO₂ nanorods as an electron pathway. Moreover, selectively grown TiO₂ nanorods increase the optical path of the incident light via scattering effects and enable a smooth coating of the active layer. Nanoimprint lithography and hydrothermal growth were employed to fabricate selectively grown TiO₂ nanorod substrates. The fabricated solar cell exhibits an efficiency of 19.86% with a current density, open-circuit voltage, and fill factor of 23.13 mA/cm², 1.120 V, and 76.69%, respectively. Time-resolved photoluminescence, ultraviolet-visible (UV–Vis) spectroscopy, and the incident photon to current efficiency (IPCE) analysis were conducted to understand the factors responsible for the improvement in characteristics of the fabricated PSCs.

     

Optical management for efficiency enhancement in hybrid organic-inorganic lead halide perovskite solar cells

In a few years only, solar cells using hybrid organic–inorganic lead halide perovskites as optical absorber have reached record photovoltaic energy conversion efficiencies above 20%. To reach and overcome such values, it is required to tailor both the electrical and optical properties of the device. For a given efficient device, optical optimization overtakes electrical one. Here, we provide a synthetic review of recent works reporting or proposing so-called optical management approaches for improving the efficiency of perovskite solar cells, including the use of anti-reflection coatings at the front substrate surface, the design of optical cavities integrated within the device, the incorporation of plasmonic or dielectric nanostructures into the different layers of the device and the structuration of its internal interfaces. We finally give as outlooks some insights into the less-explored management of the perovskite fluorescence and its potential for enhancing the cell efficiency.     

TiO2纳米碗阵列作为电子传输层构筑高效率彩色钙钛矿太阳能电池（英文）

钙钛矿太阳能电池的飞速发展及其在构筑一体化和可穿戴器件中的应用前景激发了人们对于彩色钙钛矿太阳能电池的浓厚兴趣,但如何将可见光宽波段吸收且具有高吸光系数的钙钛矿材料构筑成高性能的彩色太阳能电池仍是一个挑战.本文利用TiO2纳米碗阵列作为结构化的电子传输层,并在纳米碗内均匀填充一层CH3NH3PbI3钙钛矿薄膜,成功制备了具有鲜艳结构色的钙钛矿@TiO2纳米碗阵列薄膜,其结构色具有显著的角度依赖特征.通过路易斯酸碱加合物法制备得到基于醋酸铅的新型晶态中间体薄膜,使得高质量的CH3NH3PbI3钙钛矿薄膜能够在纳米碗内均匀填充.利用该钙钛矿@TiO2纳米碗薄膜可以制备出具有鲜艳结构色的平面异质结钙钛矿太阳能电池,其最高光电转化效率可以达到16.94%,平均效率达到15.47%,均高于现已报道的彩色钙钛矿太阳能电池的转化效率.     

Zinc octacarboxylic phthalocyanine/lutein dyads co-adsorbed nanocrystalline TiO2 electrode: enhancement in photovoltaic performance of dye-sensitized solar cells

A novel zinc phthalocyanine containing eight carboxyl groups was synthesized and utilized as a co-adsorbent with lutein for dye-sensitized solar cells enhance the photoelectric conversion efficiency. The effects of various phthalocyanine/lutein mole ratios on the performances of the fabricated solar cells were investigated. The results showed that zinc octacarboxylic phthalocyanine aggregation decreased with the increasing lutein/phthalocyanine mole ratios and zinc octacarboxylic phthalocyanine fluorescence was strongly quenched due to energy transfer from the phthalocyanine to the excited lutein. The photoelectric conversion efficiency reached its maximum when zinc octacarboxylic phthalocyanine/lutein mole ratio was 4:1. Moreover, the charge-transfer resistances and electron lifetimes at the TiO₂/dye/electrolyte interface also showed great dependency on the phthalocyanine/lutein mole ratios by electrochemical impedance spectroscopy. The density-functional theory calculation of zinc phthalocyanine suggests that the electronic cloud density distribution move from the phthalocyanine ring framework toward the anchoring carboxylic group and further to the conduction band of TiO₂, which results in efficient electron transfer.     

Heat transfer enhancement in distribution transformers using TiO2 nanoparticles

A transformer is an electrical device that transfers electrical energy between windings by electromagnetic induction while producing a considerable amount of heat in circuits. The heat produced in windings is removed by an appropriate heat transfer fluid such as liquid dielectrics. The cooling and insulating of a liquid dielectric depend on the properties of the oil filling the transformer. One of the approaches to enhance the thermal and dielectric properties of transformer oil is employing an appropriate nanoparticle in a transformer.In this paper, a three-phase distribution transformer is simulated three-dimensionally in order to study the heat transfer efficiency for pure oil (single phase) and nanofluid (TiO₂ nanoparticles- transformer oil). For both models, the electromagnetic field in solid sections and heat transfer in fluid and solid sections of the transformer are simultaneously investigated. The simulation results show that the presence of TiO₂ nanoparticles in the transformer oil increases the heat transfer coefficient, i.e. adding 1% (vol/vol) of TiO₂ nanoparticles to the transformer oil increases the Nusselt number from 2.17 to 2.49, while the maximum temperature of transformer components decreases from 47.20?°C to 43.05?°C.     

TiO_2纳米管阵列电极染料敏化太阳能电池

采用电化学阳极氧化法在纯钛片表面制备了高度有序的TiO2纳米管阵列。利用SEM、XRD分别对TiO2纳米管阵列的形貌、晶型进行了表征,并通过线性扫描伏安法对N719染料敏化纳米管阵列电极的光电性能进行了研究。实验结果表明,纳米管阵列的管径和长度随着阳极氧化电压的升高和氧化时间的延长都分别相应增加。同时还发现,通过450℃热处理的TiO2纳米管阵列,具有较好的锐钛矿晶型结构,其光电转化效率为2.1%。     

钙钛矿太阳能电池用Ag/ZrO2/C柔性纳米纤维膜电极

钙钛矿太阳能电池(perovskite solar cells,PSCs)因其制备简单、光电转化效率较高等优点而备受关注.静电纺碳纳米纤维膜(carbon nanofiber films,CNFs)具有高比表面积、良好的电学性能和化学稳定性,但其脆性限制了它的应用.利用静电纺丝法结合水热法制备柔性导电Ag/ZrO2/C复合纳米纤维膜,然后将其应用于PSCs的对电极,研究不同Ag纳米颗粒添加量对柔性复合纳米纤维膜和电池的性能影响.结果表明:当银前驱体溶液质量浓度从0 g/mL增加至0.030 g/mL时,Ag/ZrO2/C复合纳米纤维表面的Ag纳米颗粒的包覆越来越好,薄膜显示良好的柔韧性,其抗弯弹性模量为0.479 MPa,电导率从866 S/m增加到4862 S/m,提高了薄膜的空穴电子传输能力,进而增强PSCs的性能.当溶液质量浓度为0.030 g/mL时,器件具备最优的光电转换效率(6.05％)和最大电流(18.44 mA/cm2).     

Significant efficiency enhancement of carbon-based CsPbI2Br perovskite solar cells enabled by optimizing tin oxide electron transport layer

Carbon-based perovskite solar cells (C-PSCs) have been popular for achieving low-cost and stable photovoltaics. To overcome an obstacle of high-temperature annealing process for producing titanium dioxide (TiO₂), CsPbI₂Br C-PSCs based on a device structure of FTO/tin oxide (SnO₂)/CsPbI₂Br/carbon electrode can be fabricated at the low-temperature annealing process of 280 °C for 180 s, where SnO₂ is used as the electron transporting layer (ETL). Experimental results showed that the suitable concentration of SnO₂ ETL could yield smooth surface CsPbI₂Br films with free-pinhole and larger grain-sized crystallization. In combination with prolonging annealing time, a champion power conversion efficiency of 9.68% with a larger open-circuit voltage (V_oc) of 1.14 V was obtained for CsPbI₂Br C-PSC based on SnO₂ ETL. Here, a simple low-temperature fabricating process of SnO₂ ETL can be adapted to flexible substrates for C-PSCs and furtherly reduce the manufacturing cost.

     

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。     

Quasi-solid-state dye-sensitized solar cells based on TiO2/NiO core-shell nanocomposites

The core-shell nanocomposites of titanium dioxide (TiO2) and nickel oxide (NiO) used as modified photoelectrode materials in a quasi-solid-state dye-sensitized solar cell (quasi-DSSC) were synthesized using TiO2 P-25 and a nickel acetate precursor, via ball milling. The as-obtained intermediate products were annealed at 350, 450, and 550 degrees C. The structural properties of the NiO/TiO2 nanocomposites were well characterized via X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The results imply that NiO-shell-coated TiO2 nanoparticles can be obtained with the assistance of sufficient thermal energy in the system. The crystallite size of the composite increased as the annealing temperature increased. Among all the prepared conditions, the composite with 0.1 wt% NiO exhibited the best performance, with an optimized solar-energy conversion efficiency of 2.29% and with a short-circuit current density of 7.21 mA/cm2. The significant enhancement of the device's current density may be associated with the charge recombination suppression by the NiO shell, which acted as a potential barrier in the composite. The decrease in the recombination of the photo-injected electrons, and the increase in the number of electrons tunneling through the NiO layer at the interface, may have resulted from the presence of a NiO layer on the TiO2 nanoparticles.