Designing simple non-fused terthiophene-based electron acceptors for efficient organic solar cells

Low-cost photovoltaic materials are essential for realizing large-scale commercial applications of organic solar cells(OSCs).However,highly efficient OSCs based on low-cost photovoltaic materials are scarce due to a deficiency in understanding the structure-property relationship.Herein,we investigated two low-cost terthiophene-based electron acceptors,namely,3TC8 and 3TEH,with 3,4-bis(octan-3-yloxy)thiophene,differing only in the alkylated thiophene-bridges.Both acceptors exhibit low optical gaps(∼1.43 eV)and possess deep highest occupied molecular orbital(HOMO)levels(∼−5.8 eV).Notably,the single-crystal structure of 3TEH demonstrates highly planar conjugated backbone and strongπ-πstacking between intermolecular terminal groups,attributed to the presence of the bulky alkylated noncovalently conformational locks.Upon utilizing both acceptors to fabricate OSCs,the 3TC8-based device exhibited a power conversion efficiency(PCE)of 11.1%,while the 3TEH-based OSC demonstrated an excellent PCE of 14.4%.This PCE is the highest among OSCs based on terthiophene-containing electron acceptors.These results offer a new strategy for designing low-cost electron acceptors for highly efficient OSCs.

Corrosion of Q235 steel affected by Pseudodesulfovibrio cashew differed with electron acceptors

Sulfate and nitrate reducing bacteria are important culprits for microbiologically influenced corrosion(MIC)using sulfate and nitrate as electron acceptors,respectively.Sulfate and nitrate hold different standard electrode potentials,which may lead to differences in corrosion,but their effects on corrosion by the same bacteria have not been reported.The corrosion of Q235 steel affected by Pseudodesulfovibrio cashew(P.cashew)in the sulfate and nitrate media under carbon starvation was studied.It was found that sulfate and nitrate did not lead to differences in corrosion under abiotic conditions.However,P.cashew promoted corrosion in both cases,and the consumption of H_(2)was the main mechanism for MIC.In addition,corrosion was more severe in the sulfate media.The higher corrosivity of P.cashew with sulfate as the electron acceptor is closely related to the higher number of sessile cells in the biofilm,higher bacterial motility,more hydrogen production pathways,and the increased gene expression of enzymes related to energy synthesis.

Pomelo biochar as an electron acceptor to modify graphitic carbon nitride for boosting visible-light-driven photocatalytic degradation of tetracycline

In this study,biochar(BC)derived from pomelo was prepared via a high-temperature calcination method to modify the graphitic carbon nitride(g-C_(3)N_(4))to synthesize the BC/g-C_(3)N_(4)composite for the degradation of the tetracycline(TC)antibiotic under visible light irradiation.The experimental results exhibit that the optimal feeding weight ratio of biochar/urea is 0.03:1 in BC/g-C_(3)N_(4)composite could show the best photocatalytic activity with the degradation rate of tetracycline is 83%in 100 min irradiation.The improvement of photocatalytic activity is mainly attributed to the following two points:(i)the strong bonding with π-π stacking between BC and g-C_(3)N_(4)make the photogenerated electrons of light-excited g-C_(3)N_(4)transfer to BC,quickly and improve the separation efficiency of carriers;(ii)the introduction of BC reduces the distance for photogenerated electrons to migrate to the surface and increases the specific surface area for providing more active sites.This study provides a sustainable,economical and promising method for the synthesis of photocatalytic materials their application to wastewater treatment.

Effect of electron acceptors H_2O_2 and O_2 on the generated reactive oxygen species ~1O_2 and OH~· in TiO_2-catalyzed photocatalytic oxidation of glycerol

The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species（ROS）,and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was studied at ambient conditions.In the absence of an electron acceptor,only HO^·radicals were generated by irradiated UV light and TiO2.However,in the presence of the two electron acceptors,both HO^· radical and ^1O2 were produced by irradiated UV light and TiO2 in different concentrations that depended on the concentration of the electron acceptor.The use of H2O2 as an electron acceptor enhanced glycerol conversion more than O2.The type of generated value-added compounds depended on the concentration of the generated ROS.

Non-fullerene small molecule electron acceptors for high-performance organic solar cells

Fullerenes and their derivatives are important types of electron acceptor materials and play a vital role in organic solar cell devices. However, the fullerene acceptor material has some difficulties to overcome the intrinsic shortcomings, such as weak absorption in the visible range, difficulty in modification and high cost, which limit the performance of the device and the large-scale application of this type of acceptors. In recent years, non-fullerene electron acceptor material has attracted the attention of scientists due to the advantages of adjustable energy level, wide absorption, simple synthesis, low processing cost and good solubility. Researchers can use the rich chemical means to design and synthesize organic small molecules and their oligomers with specific aggregation morphology and excellent optoelectronic prop- erties. Great advances in the field of synthesis, device engineering, and device physics of non-fullerene acceptors have been achieved in the last few years. At present, non-fullerene small molecules based photovoltaic devices achieve the highest efficiency more than 13% and the efficiency gap between fullerenetype and non-fullerene-type photovoltaic devices is gradually narrowing. In this review, we explore recent progress of non-fullerene small molecule electron acceptors that have been developed and led to highefficiency photovoltaic devices and put forward the prospect of development in the future.

Molecular design towards two-dimensional electron acceptors for efficient non-fullerene solar cells

Non-fullerene polymer solar cells(NF-PSCs) have gained wide attention recently. Molecular design of non-fullerene electron acceptors effectively promotes the photovoltaic performance of NF-PSCs. However,molecular electron acceptors with 2-dimensional(2 D) configuration and conjugation are seldom reported.Herein, we designed and synthesized a series of novel 2 D electron acceptors for efficient NF-PSCs. With rational optimization on the conjugated moieties in both vertical and horizontal direction, these 2 D electron acceptors showed appealing properties, such as good planarity, full-spectrum absorption, high absorption extinction coefficient, and proper blend morphology with donor polymer. A high PCE of 9.76%was achieved for photovoltaic devices with PBDB-T as the donor and these 2 D electron acceptors. It was also found the charge transfer between the conjugated moieties in two directions of these 2 D molecules contributes to the utilization of absorbed photos, resulting in an exceptional EQE of 87% at 730 nm. This work presents rational design guidelines of 2 D electron acceptors, which showed great promise to achieve high-performance non-fullerene polymer solar cells.

Characterization of phosphorus removal bacteria in （AO）^2 SBR system by using different electron acceptors

Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An （AO）^2 SBR （anaerobic-aerobic-anoxic-aerobic sequencing batch reactor） was thereby employed to enrich denitrifying phosphorus removal bacteria for simultaneously removing phosphorus and nitrogen via auoxic phosphorus uptake, Ammonium oxidation was controlled at the first phase of the nitrification process. Nitrite-inhibition batch tests illustrated that nitrite was not an inhibitor to phosphorus uptake process, but served as an alternative electron acceptor to nitrate and oxygen if the concentration was under the inhibition level of 40mg NO2 - N·L^- 1. It implied that in addition to the two well-accepted groups of phosphorus removal bacterium （ one can only utilize oxygen as electron acceptor, P1, while the other can use both oxygen and nitrate as electron acceptor, P2 ）, a new group of phosphorus removal bacterium P3, which could use oxygen, nitrate and nitrite as electron acceptor to take up phosphorus were identified in the test system. To understand （AO）^2 SBR sludge better, the relative population of the different bacteria in this system, plus another A/O SBR sludge （ seed sludge） were respectively estimated by the phosphorus uptake batch tests with either oxygen or nitrate or nitrite as electron acceptor. The results demonstrated that phosphorus removal capability of （AO）^2 SBR sludge had a little degradation after A/O sludge was cultivated in the （AO）^2 mode over a long period of time. However, deuitrifying phosphorus removal bacteria （ P2 and P3 ） was significantly enriched showed by the relative population of the three types of bacteria, which implied that energy for aeration and COD consumption could be reduced in theory.

PHOTOINDUCED CHARGE TRANSFER POLYMERIZATION OF STYRENE INITIATED BY ELECTRON ACCEPTOR

Photoinduced charge transfer polymerization of styrene(St) with electron acceptor as initiator was investigated. In case of fumaronitrile (FN) or maleic anhydride (MA) as initiator the polymerization takes place regularly, whereas the tetrachloro-1,4-benzenequinone (TCQ), 2,3-dichloro-5, 6-dicyano-1, 4-benzenequinone (DDQ). or tetracyano ethylene (TCNE) as initiator the polymerization proceeds reluctantly only after the photoaddition reaction. A mechanism was proposed that free radicals would be formed following the charge and proton transfer in the exciplex formed between St and electron accepters.

Fused thienobenzene-thienothiophene electron acceptors for organic solar cells

Small molecule ladder-type heteroarenes IHBT-2F is designed and synthesized with strong electrondonating and molecular packing properties, where the central unit, fused thienobenzene-thienothiphene (IHBT), is attached with the strong electron-deficient 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) as the end group. The counterpart IDBT-2F with indancenodibenzothiophene (IDBT) mainchain is sythesized for comparison, in which thieno[3,2-b]thiophene (TT) core of IHBT is replaced by benzene core. Relative to benzene-core IDBT-2F, TT-core IHBT-2F shows a much higher highest occupied molecular orbital energy level (IHBT-2F:-5.46 eV;IDBT-2F:-5.72 eV) and significantly redshifted absorption, due to the π-donor capability of the sulfur atom, the larger π-conjugation and stronger intermolecular π-π stacking. The as-cast organic solar cells (OSCs) based on blends of PTB7-Th donor and IHBT-2F acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 8.74%, which is much higher than that of PTB7-Th:IDBT-2F (6.73%).

Synthesis and Cation-Mediated Electron Transfer in Fluorescence Quenching of Donor-Acceptor Podands

Reduced rate constants of photoinduced electron transfer in intramolecular fluorescence quenching of donor-acceptor podands induced by cation-complexation are observed in the highly exothermic reactions.

Degraded model of radiation-induced acceptor defects for GaN-based high electron mobility transistors(HEMTs)

Using depletion approximation theory and introducing acceptor defects which can characterize radiation induced deep-level defects in AlGaN/GaN heterostructures,we set up a radiation damage model of AlGaN/GaN high electron mobility transistor （HEMT） to separately simulate the effects of several main radiation damage mechanisms and the complete radiation damage effect simultaneously considering the degradation in mobility. Our calculated results,consistent with the experimental results,indicate that thin AlGaN barrier layer,high Al content and high doping concentration are favourable for restraining the shifts of threshold voltage in the AlGaN/GaN HEMT;when the acceptor concentration induced is less than 10^14cm-3,the shifts in threshold voltage are not obvious;only when the acceptor concentration induced is higher than 10^16cm-3,will the shifts of threshold voltage remarkably increase;the increase of threshold voltage,resulting from radiation induced acceptor,mainly contributes to the degradation in drain saturation current of the current-voltage （Ⅰ-Ⅴ） characteristic,but has no effect on the transconductance in the saturation area.

A new non-fullerene acceptor based on the heptacyclic benzotriazole unit for efficient organic solar cells

Non-fullerene acceptors(NFAs)become an interesting family of organic photovoltaic materials,and have attracted considerable interest for their great potential in manufacturing large-area flexible solar panels by low cost coating methods[1–5].Recently,our group proposed in the first time an A-DA’D-A molecular strategy and synthesized a new class of non-fullerene acceptor Y6 with a record efficiency above 15%with single junction organic solar cells(OSCs)[6].To further improve the photovoltaic performance of OSCs,many effective strategies have been successfully explored,such as side-chain engineering and extension of fused core and terminal group engineering[7–12].As well-known,PCE of devices is determined by the open circuit voltage(Voc),short-circuit current density(Jsc)and fill factor(FF)[13].Among them,Voc is associated with low-lying highest occupied molecular orbital(HOMO)of donor and lowest unoccupied molecular orbital(LUMO)of acceptor of the active layer[14–16].Side-chain engineering is an effective strategy for manipulating energy levels and improving photovoltaic performance of devices[17–19].For example,introducing the alkyl/alkoxy chains can effectively tune the HOMO/LUMO energy levels[20–22].Tang et al.have reported a novel non-fullerene acceptor ITC6-IC.ITC6-IC has relatively high LUMO level and high Voc than those of ITIC due to the introduction of weak electrondonating hexyl group on thiophene[23].

Photophysics, morphology and device performances correlation on non-fullerene acceptor based binary and ternary solar cells

Non-fullerene acceptor(NFA) based organic solar cells(OSCs) are of high efficiency and low energy loss and low recombination features, which is owing to the advantage of non-fullerene acceptors. The photophysics investigation of non-fullerene solar cells, in comparing to fullerene based analogue as well as mixed acceptor ternary blends could help to understand the working mechanism of NFA functioning mechanism. We choose PBDB-T donor, the fullerene derivative PC71 BM acceptor, and the non-fullerene acceptor ITIC as the model system, to construct binary and ternary solar cells, which then subject to ultrafast spectroscopy investigation. The charge transfer pathway in binary and ternary blends is revealed.And it is seen that ITIC leads to a faster exciton separation and exciton diffusion. ITIC in blends suppresses the geminate recombination and shows smaller amount of charge transfer states, which is beneficial for the device performance. And the addition of ITIC enhances the crystallinity for both donor and acceptor leads to a morphology change of forming bicontinuous crystalline networks and phase separation. In a consequence, fill factor and JSC, increase dramatically for the related OSC.

Theoretical Studies on the Intramolecular Electron Transfer in Some Aromatic Systems

In this work, the excited states of the title compounds are calculated by using time-dependent density functional theory (TDDFT). Firstly, the variation of the sequences of intramolecular charge local excitation (LE) and intramolecular charge transfer (CT) in the gas phase is studied by changing electron donors or acceptors. Then, the effects of Polarized Continuum Model (PCM) and Self-consistent Isodensity Polarized Continuum Model (SCI-PCM) in solvents on the calculated results are discussed. It is shown that the calculated results obtained by the PCM are in more agreement with the experimental data. Finally, the excited states of compounds in different solvents were calculated by PCM. Compared with the results obtained in gas phase, the absorption spectra of the CT state in the solvents have a larger red shift; however, the spectra for the LE state are hardly changed.

定向调控电子受体强化好氧颗粒污泥内源反硝化脱氮除磷

为强化内源反硝化作用,加强对有限碳源的高效利用,设置了1组厌氧/好氧/缺氧(A/O/A)和3组不同好氧时间分配的厌氧-两级短时好氧/缺氧(A/(O/A)_(2))序批式反应器,探究定向调控电子受体下污泥的颗粒化及反硝化聚糖菌(DGAOs)的富集情况.结果表明,采用两级短时好氧/缺氧的反应器好氧颗粒污泥结构更加致密、沉淀性能更好,缺氧段及好氧段电子受体更充足,DGAOs储存内碳源的能力得以强化,系统中反硝化聚糖菌和DGAOs对碳源的竞争达到平衡状态,系统有更高的内源反硝化脱氮率,实现了深度脱氮除磷.其中,两级短时好氧时间分配时间为前段60min/后段30min的R2的脱氮除磷效果最好,DGAOs含量最高,且颗粒沉降性能最佳.第45d,R2的COD、TN、TP去除率分别达到90.52%、85.71%、92.73%,内源反硝化效率达到58.59%,具有良好的污染物去除效果.

基于喹喔啉和吡啶并吡嗪及咔唑和二苯胺衍生物电子给体-受体结构荧光材料的合成和光电性能

通过α-二酮与邻苯二胺、吡啶二胺缩合反应,构建了喹喔啉和吡啶并吡嗪衍生物作为电子受体,分别以二苯胺、咔唑衍生物为电子给体,合成了4个具有电子给体-电子受体结构的氮杂环荧光材料F1~F4。通过低温荧光/磷光光谱、荧光寿命测试,结合密度泛函理论计算可知,F1~F4均为荧光小分子。室温荧光光谱结果表明,利用电子给体和受体的电子效应不同可以调控材料的发光颜色,其中三苯胺相对于苯基咔唑的供电子能力更强,表现为F1比F2、F3比F4红移现象更加明显;而吡啶并吡嗪具有多氮的缺电子结构,与喹喔啉相比共轭程度增加,导致F3比F1、F4比F2发生的斯托克斯位移数值增大。总之,F1~F4的甲苯溶液最大荧光光谱发射峰位于529、464、568和507 nm,荧光寿命分别为12.21、2.61、9.76和6.03 ns,荧光量子效率最高可达98.2%,具有良好的发光性能。将F1~F4发光材料掺杂在主体材料中制备了有机电致发光二极管DF1~DF4。所得器件DF1和DF3性能更好,最大电流效率分别为13.38和11.98 cd·A-1,且最大外量子效率分别达到4.8%和4.5%。

Designing high-performance nonfused ring electron acceptors via side-chain engineering

The side-chain has a significant influence on the optical properties and aggregation behaviors of the organic small molecule acceptors,which becomes an important strategy to optimize the photovoltaic performance of organic solar cells.In this work,we designed and synthesized three brand-new nonfused ring electron acceptors(NFREAs)OC4-4Cl-Ph,OC4-4Cl-Th,and OC4-4Cl-C8 with hexylbenzene,hexylthiophene,and octyl side chains on theπ-bridge units.Compared with OC4-4Cl-Ph and OC4-4Cl-Th,OC4-4Cl-C8 with linear alkyl side chain has more red-shift absorption,which is conducive to obtaining higher short-circuit current density.Additionally,the OC4-4Cl-C8 film exhibits a longer exciton diffusion distance,and the D18:OC4-4Cl-C8 blend film displays faster hole transfer,weaker bimolecular recombination,and more efficient exciton transport.Furthermore,The D18:OC4-4Cl-C8 blend films may effectively form interpenetrating networks that resemble nanofibrils,which can facilitate exciton dissociation and charge transport.Finally,OC4-4Cl-C8-based devices can be created a marvellously power conversion efficiency(PCE)of 16.56%,which is much higher than OC4-4Cl-Ph(12.29%)-and OC4-4Cl-Th-based(11.00%)ones,being the highest PCE among the NFREA based binary devices.All in all,we have validated that side-chain engineering is an efficient way to achieve high-performance NFREAs.

全小分子有机太阳能电池研究进展

近年来,非富勒烯小分子受体材料(SMAs)由于具有高吸收系数、能级和带隙可调、优异的电学性质和光伏性能等优点受到广泛关注,设计和合成高性能SMAs已成为有机太阳能电池(OSCs)的研究热点。得益于SMAs的快速发展,OSCs的能量转换效率在几年内从3%~4%提高到19%。在成功合成小分子受体材料ITIC和Y6基础上,研究人员对分子结构设计进行了深入研究,开发出许多性能优异的SMAs。这些SMAs在提高器件效率和太阳能电池性能方面发挥了至关重要的作用。综述了全小分子OSCs的研究进展,并展望了未来OSCs的发展方向。

基于污水同步脱氮除磷的反硝化聚磷菌的研究与展望

与传统的好氧除磷技术相比,反硝化除磷具有节约碳源、一碳两用、减少污泥产量等优点。综述了反硝化脱氮除磷过程中的主要功能微生物反硝化聚磷菌的培养、分离筛选、电子受体利用等研究的相关进展,总结了近年来研究中常见的反硝化聚磷菌,并对其未来的发展前景做出展望。

EDA复合物介导的光催化合成全氟取代异喹啉二酮

本文开发了一个由电子供体受体(EDA)复合物介导、可见光诱导合成全氟取代异喹啉二酮骨架的反应。该反应无需过渡金属光敏剂催化,反应条件温和,具有绿色环保、清洁高效的特点。