High‐Performance All‐Polymer Solar Cells: Synthesis of Polymer Acceptor by a Random Ternary Copolymerization Strategy

Demonstrated in this work is a simple random ternary copolymerization strategy to synthesize a series of polymer acceptors, PTPBT‐ET_x, by polymerizing a small‐molecule acceptor unit modified from Y6 with a thiophene connecting unit and a controlled amount of an 3‐ethylesterthiophene (ET) unit. Compared to PTPBT of only Y6‐like units and thiophene units, PTPBT‐ET_x (where x represents the molar ratio of the ET unit) with an incorporated ET unit in the ternary copolymers show up‐shifted LUMO energy levels, increased electron mobilities, and improved blend morphologies in the blend film with the polymer donor PBDB‐T. And the all‐polymer solar cell (all‐PSC) based on PBDB‐T:PTPBT‐ET_0.3 achieved a high power conversion efficiency over 12.5 %. In addition, the PTPBT‐ET_0.3‐based all‐PSC also exhibits long‐term photostability over 300 hours.     

Crystalline Conjugated Polymers for Organic Solar Cells: From Donor,Acceptor to Single‐Component

Organic solar cells have made rapid progress in the last two decades due to the innovation of conjugated materials and photovoltaic devices. Microphase separation that connects with materials and devices plays a crucial role in the charge generation process. In this account, we summary our recent works of developing new crystalline conjugated polymers to control the microphase separation in thin films in order to realize high performance in solar cells, including crystalline diketopyrrolopyrrole‐based donor polymers, perylene bisimide‐based electron acceptors, and “double‐cable” conjugated polymers that contain covalently‐linked crystalline donor and acceptor in one material for single‐component organic solar cells.     

High-Performance All-Polymer Solar Cells: Synthesis of Polymer Acceptor by a Random Ternary Copolymerization Strategy

Demonstrated in this work is a simple random ternary copolymerization strategy to synthesize a series of polymer acceptors, PTPBT-ET_x, by polymerizing a small-molecule acceptor unit modified from Y6 with a thiophene connecting unit and a controlled amount of an 3-ethylesterthiophene (ET) unit. Compared to PTPBT of only Y6-like units and thiophene units, PTPBT-ET_x (where x represents the molar ratio of the ET unit) with an incorporated ET unit in the ternary copolymers show up-shifted LUMO energy levels, increased electron mobilities, and improved blend morphologies in the blend film with the polymer donor PBDB-T. And the all-polymer solar cell (all-PSC) based on PBDB-T:PTPBT-ET_0.3 achieved a high power conversion efficiency over 12.5 %. In addition, the PTPBT-ET_0.3-based all-PSC also exhibits long-term photostability over 300 hours.     

Monodisperse Dual‐Functional Upconversion Nanoparticles Enabled Near‐Infrared Organolead Halide Perovskite Solar Cells

Extending the spectral absorption of organolead halide perovskite solar cells from visible into near‐infrared (NIR) range renders the minimization of non‐absorption loss of solar photons with improved energy alignment. Herein, we report on, for the first time, a viable strategy of capitalizing on judiciously synthesized monodisperse NaYF₄:Yb/Er upconversion nanoparticles (UCNPs) as the mesoporous electrode for CH₃NH₃PbI₃ perovskite solar cells and more importantly confer perovskite solar cells to be operative under NIR light. Uniform NaYF₄:Yb/Er UCNPs are first crafted by employing rationally designed double hydrophilic star‐like poly(acrylic acid)‐block‐poly(ethylene oxide) (PAA‐b‐PEO) diblock copolymer as nanoreactor, imparting the solubility of UCNPs and the tunability of film porosity during the manufacturing process. The subsequent incorporation of NaYF₄:Yb/Er UCNPs as the mesoporous electrode led to a high efficiency of 17.8 %, which was further increased to 18.1 % upon NIR irradiation. The in situ integration of upconversion materials as functional components of perovskite solar cells offers the expanded flexibility for engineering the device architecture and broadening the solar spectral use.     

Metal‐Free Organic Dyes for Dye‐Sensitized Solar Cells: From Structure: Property Relationships to Design Rules

Works without ruthenium as well : Dye‐sensitized solar cells (DSSCs) incorporating metal‐free organic dyes have been considerably improved in recent years. Various design strategies have been established and are employed successfully in the synthesis of novel sensitizers. In this Review, structure–property–efficiency correlations are deduced from a vast number of dyes, which should help to design new and highly efficient sensitizers.

     

Towards Green Synthesis and Processing of Organic Solar Cells

In 2018, several major breakthroughs have been achieved in organic solar cells (OSCs) with the record power conversion efficiency (PCE) reaching over 17 %. With this increased efficiency, it is time to take a step forward to consider how to convert this technology into large scale production. For this, the economic and environmental profile of OSCs should be taken seriously‐simplified synthetic routes and green chemistry methods should be applied. According to previous studies, OSCs are competitive and profitable in the commercial market. However, toxic and/or hazardous chemicals are currently used in materials synthesis and device fabrication of OSCs. In this account, we will talk about contributions and efforts we have made to minimize the economic and environmental disadvantages in the production of OSCs. We will start with the background on how our projects were conceived and will specifically discuss our work on direct arylation and green solvent. Developments of direct arylation for synthesizing conjugated polymers will be illustrated along with our recent finding regarding the effect of green solvents on device performance and stability.     

The Rise of Dye-Sensitized Solar Cells: From Molecular Photovoltaics to Emerging Solid-State Photovoltaic Technologies

Over the past three decades, dye-sensitized solar cells (i. e. Grätzel cells) have evolved from a pioneering concept of molecular photovoltaics to large-scale industrial deployment. In this review article, we provide a historical overview of the developments with a focus on the scientific advancements that have set the stage for this technology to emerge and thrive. This involves insights into the (photo)electrochemistry of the underlying processes, molecular engineering of dyes, redox shuttles, and hole-transporting materials, as well as their implementation into solar cells. We further outline applications and future perspectives, involving the long-lasting objective to develop efficient solid-state alternatives to conventional dye-sensitized solar cells.     

SiO2/TiO2 Hollow Nanoparticles Decorated with Ag Nanoparticles: Enhanced Visible Light Absorption and Improved Light Scattering in Dye‐Sensitized Solar Cells

Hollow SiO₂/TiO₂ nanoparticles decorated with Ag nanoparticles (NPs) of controlled size (Ag@HNPs) were fabricated in order to enhance visible‐light absorption and improve light scattering in dye‐sensitized solar cells (DSSCs). They exhibited localized surface plasmon resonance (LSPR) and the LSPR effects were significantly influenced by the size of the Ag NPs. The absorption peak of the LSPR band dramatically increased with increasing Ag NP size. The LSPR of the large Ag NPs mainly increased the light absorption at short wavelengths, whereas the scattering from the SiO₂/TiO₂ HNPs improved the light absorption at long wavelengths. This enabled the working electrode to use the full solar spectrum. Furthermore, the SiO₂ layer thickness was adjusted to maximize the LSPR from the Ag NPs and avoid corrosion of the Ag NPs by the electrolyte. Importantly, the power conversion efficiency (PCE) increased from 7.1 % with purely TiO₂‐based DSSCs to 8.1 % with HNP‐based DSSCs, which is an approximately 12 % enhancement and can be attributed to greater light scattering. Furthermore, the PCEs of Ag@HNP‐based DSSCs were 11 % higher (8.1 vs. 9.0 %) than the bare‐HNP‐based DSSCs, which can be attributed to LSPR. Together, the PCE of Ag@HNP‐based DSSCs improved by a total of 27 %, from 7.1 to 9.0 %, due to these two effects. This comparative research will offer guidance in the design of multifunctional nanomaterials and the optimization of solar‐cell performance.     

全固态介观太阳能电池:从染料敏化到钙钛矿

介观太阳能电池(Mesoscopic Solar Cells)作为新一代太阳能电池的突出代表, 具有原材料来源丰富, 制备工艺简单, 光电转换效率高等优点, 从而具有广阔的应用前景. 本工作简要评述了全固态介观太阳能电池从染料敏化太阳能电池(Dye-sensitized solar cells)发展到钙钛矿太阳能电池(Perovskite solar cells)过程中新材料、新技术和新概念的研究进展. 1998年, Grätzel课题组首次将固态有机空穴传输材料spiro-OMeTAD应用到染料敏化太阳能电池中, 制备出全固态染料敏化太阳能电池, 虽然仅获得了0.74%的光电转换效率, 但是却使得全固态染料敏化太阳能电池迅速发展成为介观太阳能电池的重要研究方向. 2012年, Park与Grätzel课题组合作, 使用钙钛矿型吸光材料(CH₃NH₃)PbI₃作为敏化剂, spiro-OMeTAD作为空穴收集层, 制备出光电转换效率达到9.7%的全固态介观太阳能电池, 又被称为钙钛矿太阳能电池. 自此, 基于钙钛矿材料的介观太阳能电池迅速成为太阳能电池领域的研究热点. 目前, 钙钛矿太阳能电池的最高公证效率已经达到20.1%. 钙钛矿太阳能电池作为介观太阳能电池商业化道路上里程碑式的突破, 在材料开发、界面优化以及器件稳定性方面的研究仍充满挑战, 也期待新的突破.     

苯并噻二唑单元在聚合物光伏材料设计中的应用

聚合物太阳能电池因其易于加工、可制备成柔性器件、材料来源广泛等优点得到材料界和能源界的广泛关注。有机太阳能电池效率的不断提高主要得益于材料的发展和电池器件结构的优化。从材料设计角度考虑,种类众多的给体和受体单元被开发用来构建有机共轭分子,其中,苯并噻二唑单元由于共轭平面较大和吸电子性较强的特性被广泛用于构建高性能的有机太阳能电池材料。基于此,本文首先介绍了苯并二噻吩单元及其衍生物常见的合成方法,随后总结了其在构建聚合物给体方面的应用,最后对其后续发展方向和前景提出了展望。     

Treatment of TiO2 with COOH‐Functionalized Germanium Nanoparticles to Enhance the Photocurrent of Dye‐Sensitized Solar Cells

A dye‐sensitized solar cell (DSSC) containing a TiO₂ film treated with COOH‐functionalized germanium nanoparticles (Ge COOH Nps) exhibited a higher short‐circuit photocurrent density (J_sc; 15.4 mA cm⁻²) compared to the corresponding untreated DSSC (13.4 mA cm⁻²) using N719 and a 12 μm thick TiO₂ film at 100 mW cm⁻². The amount of N719 attached to the treated TiO₂ film was 21 % greater than that attached to the untreated TiO₂ film. Enhancement of the J_sc value by 15 % was attributed mostly to an intramolecular charge transfer from N719 attached to the Ge COOH Nps to the TiO₂ conduction band through the Ge COOH Nps.     

Bifunctional Dendrimers: From Robust Synthesis and Accelerated One‐Pot Postfunctionalization Strategy to Potential Applications

A fourth wheel : Two sets of bifunctional AB₂C dendrimers having internal acetylene/azides and external hydroxy groups were constructed utilizing benign synthetic protocols. An in situ postfunctionalization strategy was successfully carried out to illustrate the chemoselective nature of these dendrimers. The dendrimers were also transformed into dendritic nanoparticles or utilized as dendritic crosslinkers for the fabrication hydrogels.

     

卟啉化合物在有机染料敏化太阳能电池中的应用研究

卟啉化合物具有共轭的平面结构、良好的电子缓冲性和光电磁性,特别在可见光区和近红外区域具有优越的光捕获特性。近年来,卟啉类化合物以其优异的特性在有机太阳能电池领域,尤其是染料敏化太阳能电池中得到了广泛的应用研究。人们通过对卟啉分子进行改性来提高相应的太阳能电池效率,比如增加分子的共轭度、在分子上引入长烷基链、引入功能化小...     

Synthesis and Computational Characterization of Organic UV-Dyes for Cosensitization of Transparent Dye-Sensitized Solar Cells

The fabrication of colorless and see-through dye-sensitized solar cells (DSCs) requires the photosensitizers to have little or no absorption in the visible light region of the solar spectrum. However, a trade-off between transparency and power conversion efficiency (PCE) has to be tackled, since most transparent DSCs are showing low PCE when compared to colorful and opaque DSCs. One strategy to increase PCE is applying two cosensitizers with selective conversion of the UV and NIR radiation, therefore, the non-visible part only is absorbed. In this study, we report synthesis of novel five UV-selective absorbers, based on diimide and Schiff bases incorporating carboxyl and pyridyl anchoring groups. A systematic computational investigation using density functional theory (DFT) and time-dependent DFT approaches was employed to evaluate their prospect of application in transparent DSCs. Experimental UV/Vis absorption spectra showed that all dyes exhibit an absorption band covering the mid/near-UV region of solar spectrum, with a bathochromic shift and a hyperchromic shifts for Py-1 dye. Computational results showed that the studied dyes satisfied the basic photophysical and energetics requirements of operating DSC as well as the stability and thermodynamical spontaneity of adsorption onto surface of TiO₂. However, results revealed outperformance of the thienothiophene core-containing Py-1 UV-dye, owing to its advantageous structural attributes, improved conjugation, intense emission, large Stokes shift and maximum charge transferred to the anchor. Chemical compatibility of Py-1 dye was then theoretically investigated as a potential cosensitizer of a reference VG20-C2 NIR-dye. By the judicious selection of pyridyl anchor-based UV-absorber (Py-1) and carboxyl anchor-based NIR-absorber (VG20), the advantage of the optical complementarity and selectivity of different TiO₂-adsorption-site (Lewis- and Bronsted-acidic) can be achieved. An improved overall PCE is estimated accordingly.     

有机太阳能电池简介与展望

太阳能是一种非常重要的可再生能源。将太阳能转化为电能的有机太阳能电池,因其具有重量轻,柔韧性好,可以进行大面积、低成本的柔性制备等优点,为解决未来全球的能源问题提供了一种选择。简要介绍了有机太阳能电池的发展、性能参数、工作机理和应用实例。     

Sodium‐Naphthalenide‐Driven Synthesis of Base‐Metal Nanoparticles and Follow‐up Reactions

Mo⁰, W⁰, Fe⁰, Ru⁰, Re⁰, and Zn⁰ nanoparticles—essentially base metals—are prepared as a general strategy by a sodium naphthalenide ([NaNaph])‐driven reduction of simple metal chlorides in ethers (1,2‐dimethoxyethane (DME), tetrahydrofuran (THF)). All the nanoparticles have diameters ≤10 nm, and they can be obtained either as powder samples or long‐term stable suspensions. Direct follow‐up reactions (e.g., Mo⁰+S₈, FeCl₃+AsCl₃, ReCl₅+MoCl₅), moreover, allow the preparation of MoS₂, FeAs₂, or Re₄Mo nanoparticles of similar size as the pristine metals (≤10 nm).